https://firepra.epri.com/api.php?action=feedcontributions&feedformat=atom&user=User FirePRA - User contributions [en] 2026-04-20T16:33:05Z User contributions MediaWiki 1.34.1 https://firepra.epri.com/index.php?title=MediaWiki:Common.css&diff=1222 MediaWiki:Common.css 2025-08-05T21:27:53Z <p>User: </p> <hr /> <div>/* CSS placed here will be applied to all skins */<br /> #p-namespaces,<br /> #pt-login, #p-tb, #ca-history, #ca-viewsource, #ca-talk{<br /> display:none!important;<br /> }<br /> <br /> /* CSS placed here will be applied to all skins */<br /> #pt-logout a{<br /> content: &quot;&quot;;<br /> visibility: hidden;<br /> }<br /> <br /> #pt-logout a:before{<br /> content: &quot;Admin Logout&quot;;<br /> visibility: visible;<br /> }<br /> <br /> #pt-login a{<br /> content: &quot;&quot;;<br /> visibility: hidden;<br /> }<br /> <br /> #pt-login a:before{<br /> content: &quot;Administration&quot;;<br /> visibility: visible;<br /> }</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1221 Fire Ignition Frequency (Task 6) 2025-01-20T16:20:33Z <p>User: /* Current FPRA Counting Guidance and Fire Ignition Frequencies */</p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with load centers operating between 480 and 1000 Volts. Bin 16.a includes load centers at typical nominal system voltage ranging from 480 VAC to 1000 VAC but also includes system voltages down to 440 VAC.<br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Only count load center supply circuit breakers for HEAF susceptibility - this is the most likely location of a load center HEAF. Do not assign a HEAF count to load centers without bus supply circuit breakers. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 5.32E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults associated with medium-voltage switchgear. <br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each switchgear bank is counted as one. <br /> <br /> Medium-voltage switchgear should be counted by the entire switchgear bank (e.g., an entire bank is counted as one. <br /> <br /> Because switchgear's physical and electrical functions may differ, the plant one-line diagram should be reviewed to assist in defining switchgear banks. In some cases, the switchgear physically appears as a single bank, but electrically functions as two adjacent banks (i.e., the main bus bars of each bank are separated). If the banks are electrically separated but appear as one they should be counted individually. <br /> <br /> In addition to apportioning via switchgear bank, a MV switchgear weighting factor is also applied to the plant-wide 16.b frequency (see Section 5.2.2.3 of NUREG-2262 for full details). The MV switchgear weighting factor applies 86% of the Bin 16.b frequency to Zone 1. The remaining 14% of the Bin 16.b frequency is applied to Zone 2. If Zone 2 does not have MV switchgear, then use the entire frequency for Zone 1. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 1.98E-03<br /> Zone 1: 1.70E-03<br /> Zone 2: 2.77E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.1-1<br /> | Plant-Wide Components<br /> | HEAF for segmented (non-segregated) bus ducts (Zones BDUAT and BDSAT)<br /> | HEAFs associated with segmented bus ducts located in Zone BDUAT and Zone BDSAT. <br /> <br /> Consistent with NUREG/CR-6850, Supplement 1, because NSBD (category 1) and cable ducts (category 3) have no transition points other than the termination at the end device, treatment of bus duct faults independent from the treatment of fire for the end device is not required. That is arc faults for categories 1 and 3 of bus ducts are inherently included in the treatment of the end device and no further treatment is needed. <br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | The analyst will need to choose between one of two counting practices; for known transition points (see Section 5.2.3.1 of NUREG-2262 for full details) or for unknown transition points (see Section 5.2.3.2 for full details). The choice will be dependent on whether or not the transition points can be identified. <br /> <br /> Counting approach 1 (For Known Transition Points): The counting is based on the total number of transition points within the bin (identified by external visual inspection or based on plant electrical construction drawings). Although transition points may not be generally known, certain locations may point to the presence of a transition point (e.g., geometric factors such as horizontal direction change or changes in elevation suggest the presence of a transition point). <br /> <br /> Counting approach 2 (For Unknown Transition Points): Based on the total length of the segmented bus duct within the bin. A per-linear-foot frequency can then be estimated by dividing the plant-wide frequency by the total length of segmented bus duct within the bin. <br /> <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 2.61E-03<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> |-<br /> | 16.1-2<br /> | Plant-Wide Components<br /> | HEAF for segmented (non-segregated) bus ducts (Zones BD1, BD2, and BDLV)<br /> | HEAFs associated with segmented bus ducts located in Zone BD1, Zone BD2, and Zone LVBD<br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | The analyst will need to choose between one of two counting practices; for known transition points (see Section 5.2.3.1 of NUREG-2262 for full details) or for unknown transition points (see Section 5.2.3.2 for full details). The choice will be dependent on whether or not the transition points can be identified. <br /> <br /> Counting approach 1 (For Known Transition Points): The counting is based on the total number of transition points within the bin (identified by external visual inspection or based on plant electrical construction drawings). Although transition points may not be generally known, certain locations may point to the presence of a transition point (e.g., geometric factors such as horizontal direction change or changes in elevation suggest the presence of a transition point). <br /> <br /> Counting approach 2 (For Unknown Transition Points): Based on the total length of the segmented bus duct within the bin. A per-linear-foot frequency can then be estimated by dividing the plant-wide frequency by the total length of segmented bus duct within the bin. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 8.98E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing (segregated bus ducts). The primary use of iso-phase buses is generally limited to the bus work connecting the main generator to the main and auxiliary transformers.<br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.01E-03<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1220 Fire Ignition Frequency (Task 6) 2025-01-20T15:53:30Z <p>User: /* Current FPRA Counting Guidance and Fire Ignition Frequencies */</p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with load centers operating between 480 and 1000 Volts. Bin 16.a includes load centers at typical nominal system voltage ranging from 480 VAC to 1000 VAC but also includes system voltages down to 440 VAC.<br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Only count load center supply circuit breakers for HEAF susceptibility - this is the most likely location of a load center HEAF. Do not assign a HEAF count to load centers without bus supply circuit breakers. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 5.32E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults associated with medium-voltage switchgear. <br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each switchgear bank is counted as one. <br /> <br /> Medium-voltage switchgear should be counted by the entire switchgear bank (e.g., an entire bank is counted as one. <br /> <br /> Because switchgear's physical and electrical functions may differ, the plant one-line diagram should be reviewed to assist in defining switchgear banks. In some cases, the switchgear physically appears as a single bank, but electrically functions as two adjacent banks (i.e., the main bus bars of each bank are separated). If the banks are electrically separated but appear as one they should be counted individually. <br /> <br /> In addition to apportioning via switchgear bank, a MV switchgear weighting factor is also applied to the plant-wide 16.b frequency (see Section 5.2.2.3 of NUREG-2262 for full details). The MV switchgear weighting factor applies 86% of the Bin 16.b frequency to Zone 1. The remaining 14% of the Bin 16.b frequency is applied to Zone 2. If Zone 2 does not have MV switchgear, then use the entire frequency for Zone 1. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 1.98E-03<br /> Zone 1: 1.70E-03<br /> Zone 2: 2.77E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing (segregated bus ducts). The primary use of iso-phase buses is generally limited to the bus work connecting the main generator to the main and auxiliary transformers.<br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.01E-03<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1219 Fire Ignition Frequency (Task 6) 2025-01-20T15:40:48Z <p>User: /* Current FPRA Counting Guidance and Fire Ignition Frequencies */</p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with load centers operating between 480 and 1000 Volts. Bin 16.a includes load centers at typical nominal system voltage ranging from 480 VAC to 1000 VAC but also includes system voltages down to 440 VAC.<br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Only count load center supply circuit breakers for HEAF susceptibility - this is the most likely location of a load center HEAF. Do not assign a HEAF count to load centers without bus supply circuit breakers. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 5.32E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults associated with medium-voltage switchgear. <br /> <br /> Note: In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each switchgear bank is counted as one. <br /> <br /> Medium-voltage switchgear should be counted by the entire switchgear bank (e.g., an entire bank is counted as one. <br /> <br /> Because switchgear's physical and electrical functions may differ, the plant one-line diagram should be reviewed to assist in defining switchgear banks. In some cases, the switchgear physically appears as a single bank, but electrically functions as two adjacent banks (i.e., the main bus bars of each bank are separated). If the banks are electrically separated but appear as one they should be counted individually. <br /> <br /> In addition to apportioning via switchgear bank, a MV switchgear weighting factor is also applied to the plant-wide 16.b frequency (see Section 5.2.2.3 of NUREG-2262 for full details). The MV switchgear weighting factor applies 86% of the Bin 16.b frequency to Zone 1. The remaining 14% of the Bin 16.b frequency is applied to Zone 2. If Zone 2 does not have MV switchgear, then use the entire frequency for Zone 1. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 1.98E-03<br /> Zone 1: 1.70E-03<br /> Zone 2: 2.77E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1218 Fire Ignition Frequency (Task 6) 2025-01-20T15:13:25Z <p>User: </p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with load centers operating between 480 and 1000 Volts. Bin 16.a includes load centers at typical nominal system voltage ranging from 480 VAC to 1000 VAC but also includes system voltages down to 440 VAC.<br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Only count load center supply circuit breakers for HEAF susceptibility - this is the most likely location of a load center HEAF. Do not assign a HEAF count to load centers without bus supply circuit breakers. <br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> | 5.32E-04<br /> | [https://www.epri.com/research/products/000000003002025942 EPRI 3002025942 / NUREG-2262]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1217 Fire Ignition Frequency (Task 6) 2025-01-20T14:58:21Z <p>User: /* Current FPRA Counting Guidance and Fire Ignition Frequencies */</p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1216 Fire Ignition Frequency (Task 6) 2025-01-20T14:57:35Z <p>User: /* Current FPRA Counting Guidance and Fire Ignition Frequencies */</p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=Fire_Ignition_Frequency_(Task_6)&diff=1215 Fire Ignition Frequency (Task 6) 2025-01-20T14:55:54Z <p>User: /* Current FPRA Counting Guidance and Fire Ignition Frequencies */</p> <hr /> <div>==Task Overview==<br /> <br /> ===Background===<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ===Purpose===<br /> This section describes the procedure for estimating the fire-ignition frequencies associated with fire ignition sources. Generic ignition frequencies that can be specialized to plant conditions in terms of plant characteristics and plant fire event experience are provided. Uncertainties in the generic frequencies are also provided in terms of 5th, 50th, and 95th percentiles. <br /> <br /> ===Scope===<br /> This work package addresses the following fire-ignition frequency related issues:<br /> <br /> * Plant specific fire event data review and generic fire frequency update using Bayesian approach,<br /> * Equipment (ignition source) count by compartment, <br /> * Apportioning of ignition frequencies according to compartment-specific configurations, and <br /> * Uncertainty considerations in the fire frequencies.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Ignition Frequency (IGN)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies<br /> <br /> Appendix F, Appendix for Chapter 8, Walkdown Forms<br /> <br /> ==Current FPRA Counting Guidance and Fire Ignition Frequencies==<br /> <br /> Table 6-1 presents relevant information such as bin, ignition source, counting guidance, and mean fire ignition frequency for ignition sources counted in the Fire PRA. In many cases, the counting guidance provided in NUREG/CR-6850 has been supplemented by additional guidance including formally published in NUREG/CR-6850 Supplement 1 and through the frequently asked questioned (FAQ) process. Links to the counting guidance is provided in the &quot;Counting Reference&quot; column. Similarly, the fire ignition frequencies published in NUREG/CR-6850 are no longer the most current. A second set of fire ignition frequencies was published in NUREG/CR-6850 Supplement 1 (Chapter 10, FAQ 08-0048). A [https://www.nrc.gov/docs/ML1513/ML15134A046.pdf memo on May 14, 2015 from the NRC], clarified that the fire ignition frequencies in NUREG/CR-6850 Supplement 1 (FAQ 08-0048) should be replaced with the most current guidance in EPRI 3002002936 (NUREG-2169). <br /> <br /> '''Table 6-1: Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Each bank of interconnected sets of batteries located in one place (often referred to as Battery Room).<br /> | Interconnected sets of batteries is counted as one. Cells may not be counted individually.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.96E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pump<br /> | The reactor coolant pumps (RCPs) are distinct devices in PWRs that vary between two and four, depending on primary loop design. <br /> | Each reactor coolant pump is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.37E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | General transient combustibles and hotwork activities located in Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.21E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | A control room typically consists of one or two (depending on the number of units) main control boards as the central element of the room.<br /> | Each main control board, typically consisting of the main horseshoe and nothing else, is counted separately. This bin may also include &quot;benchboard&quot; panels that are detached from, but directly in front of, the main horseshoe (at some plants such panels are referred to as &quot;consoles&quot;). FAQ-14-0008 also clarified that the rear side of the MCB may be treated as part of the MCB if both the rear and front sides are connected together as a single enclosure (including a continuous overhead, or by an overhead with penetrations or vents along it longitudinally, cabinet ceiling, or cables connecting the front and back sides of the MCB). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0018, Section 5 of Supplement 1]<br /> <br /> [https://www.nrc.gov/docs/ML1419/ML14190B307.pdf FAQ 14-0008]<br /> | 2.05E-3<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Control Building, Auxiliary Building, or Reactor Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.83E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850] <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.44E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | General transient combustibles or activities located in the Control Building, Auxiliary Building, or Reactor Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. Developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 3.33E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | Diesel generators are generally well-defined items that include a set of auxiliary subsystems associated with each engine. All diesel generators that are included in the electric power recovery model should be counted here. In addition to the normal safety related diesel generators, this may include the Technical Support Center diesel generators, Security diesel generators, etc. It is recommended that each diesel generator and its subsystems be counted as one unit. The subsystems may include diesel generator air start compressors, air receiver, batteries and fuel storage, and delivery system. <br /> | Each diesel generator should be counted separately. It is recommended that the electrical cabinets for engine and generator control that stand separate from the diesel generator be included as part of “Plant-Wide Components - Electrical Cabinets.” Control panels that are attached to engine may be counted as part of the engine.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 7.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | This bin covers the large air compressors that provide plant instrument air included in the Internal Events PRA Model. These compressors are generally well-defined devices. They may include an air receiver, air dryer, and control panel attached to the compressor. These items should be considered part of the air compressor. If portable compressors are part of the model, those compressors should also be included in the equipment count for this bin. <br /> | Air compressors are generally well-defined devices (and includes portable units credited in the PRA model). The air compressor skid, which could include an air receiver, air dryer, and control panel attached to the compressor, should be counted as one, as they are considered to be part of the air compressor. NOTE: Compressors associated with the ventilation systems and small air compressors used for specialized functions are NOT part of this bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | These are generally well defined items associated with DC buses.<br /> | Each battery charger should be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR)).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 2.77E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | Self-ignited cables fires postulated in fire compartments with unqualified cables only or a mix of qualified cables and unqualified cables. <br /> | The cable loading of each compartment should be established using the same approach as that for Bin 5, except that, in this case, all plant fire compartments should be taken into account. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). For rooms where detailed fire modeling is necessary FAQ 13-0005 provides guidance on how to calculate a scenario level ignition frequency (by dividing the quantity of cables in the tray on fire by the total quantity of cable in the room). <br /> Consistent with Appendix R of EPRI 1011989, self-ignited cable fire only need to be postulated in compartments which contain unqualified cable types.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ 13-0005]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 7.02E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | Clothes dryers are generally well-defined units. <br /> | Each clothes dryer is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.66E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | Electrical motors with a power rating greater than 5hp associated with various devices, not including those counted in other bins, are included in this bin. This may include elevator motors, valve motors, etc. <br /> | Motors (not included those counted in other bins) with a rating greater than 5 HP are counted. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing. See FAQ 07-0031 for the additional guidance.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 5.43E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | Electrical cabinets represent such items as switchgears, motor control centers, DC distribution panels, relay cabinets, control and switch panels (excluding panels that are part of machinery), fire protection panels, etc. <br /> | &lt;div id=&quot;IgnBin15&quot;&gt;&lt;/div&gt;Electrical cabinets in a nuclear power plant vary significantly in size, configuration, and voltage. Size variation range from small-wall mounted units to large walk-through vertical control cabinets, which can be 20’ to 30’ long. The configuration can vary based on number of components that contribute to ignition, such as relays and circuit cards, and combustible loading, which also affects the fire frequency. Voltages in electrical cabinets vary from low voltage (120 V) panels to 6.9 kV switchgear. Even though it is expected that these features affect the likelihood of fire ignition, from a simple analysis of the event data involving the electrical cabinets, it was determined that the variation by cabinet type did not warrant separate frequency evaluation. Therefore, one fire frequency was estimated for the electrical cabinets.<br /> The following rules should be used for counting electrical cabinets: <br /> <br /> – Simple wall-mounted panels housing less than four switches may be excluded from the counting process, <br /> <br /> – Well-sealed electrical cabinets that have robustly secured doors (and/or access panels) and that house only circuits below 440V should be excluded from the counting process, (In this context, the term “well-sealed” means there are no open or unsealed penetrations, there are no ventilation openings, and potential warping of the sides/walls of the panel would not open gaps that might allow an internal fire to escape. “Robustly secured” means that any doors and/or access panels are all fully and mechanically secured and will not create openings or gaps due to warping during an internal fire. For example, a panel constructed of sheet metal sides “tack welded” to a metal frame would not be considered well-sealed because internal heating would warp the side panels allowing fire to escape through the resulting gaps between weld points. A panel with a simple twist-handle latch mechanism would not be considered robustly secured because the twist handle would not prevent warping of the door under fire conditions. In contrast, a water-tight panel whose door/access panel is bolted in place or secured by mechanical bolt-on clamps around its perimeter would be considered both well-sealed and robustly secured. Also note that panels that house circuit voltages of 440V or greater are counted because an arcing fault could compromise panel integrity (an arcing fault could burn through the panel sides, but this should not be confused with the high energy arcing fault type fires)). <br /> <br /> – Free-standing electrical cabinets should be counted by their vertical segments. NUREG/CR-6850 (EPRI 1011989) provided guidance to count cabinets in a “typical” or visible vertical section configuration, however additional guidance was necessary for panels with “atypical” configuration where the guidance for vertical segments could be interpreted in different ways. FAQ 06-0016 was proposed to clarify guidance on electrical panel/cabinet counting for fire frequency. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0016, Section 3 of Supplement 1]<br /> | 3.43E-02<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG-2230 / EPRI 3002016051]<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> <br /> In 2023, new HEAF guidance was published. The prior guidance remains an acceptable approach. For prior HEAF bin descriptions, counting guidance, counting reference, fire ignition frequency, and fire ignition frequency reference please see [https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance Prior HEAF counting guidance]<br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | Hydrogen storage tanks are generally well-defined items. Multitank hydrogen trailers, because they are interconnected, should be counted as one unit. <br /> | Each hydrogen tank should be counted separately. Multitank hydrogen trailers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.93E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | Generally, a junction box is defined as a fully enclosed metal box containing terminals for joining or splicing cables. The box must be fully enclosed with metal panels or welded together but not necessarily well sealed. Cables entering or exiting the junction box should be in metal conduits and have mechanical connections to the metal box. The junction box should include only terminals for joining and splicing cables. For a full definition, refer to FAQ 13-0006. <br /> | The number of junction boxes may be difficult to determine. The frequency can be apportioned based on ratio of cables in the area to the total cable in the plant. Therefore, the ignition source-weighting factor of the cables may be used for this bin as well. <br /> <br /> As an alternative (described in FAQ 13-0006), the frequency of junction box fires in each fire compartment can be apportioned based on the number of junction boxes in the fire compartment divided by the total number of junction boxes in the plant as determined by the cable and raceway database system or when the cable and raceway database cannot provide this information, the number of junction boxes may be estimated in each fire compartment. See FAQ 13-0006 for full guidance. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ 13-0006]<br /> | 3.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | This bin includes hydrogen fires in miscellaneous systems other than hydrogen cylinder storage, generator cooling, and battery rooms. It is not necessary to count the ignition sources related to this bin.<br /> | Each system found in miscellaneous hydrogen systems should be counted separately. This does not include hydrogen cylinder storage, generator cooling, and battery rooms. An alternative is to not count the ignition sources related to this bin and to establish an ignition frequency associated with the components of this bin for a specific compartment or a pipe segment.<br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 34, all hydrogen-carrying items of the plant are properly accounted for.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.82E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H2 Recombiner (BWR)<br /> | Generally there are at least two recombiner systems per BWR. <br /> | Each recombiner system should be counted as one unit.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.81E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | This bin includes pumps and large hydraulic valves. Due to a lack of sufficient statistical data, a separate bin was not defined for large valves that include hydraulic fluid powered mechanisms. It is recommended such valves (e.g. Main Steam Isolation Valves, and Turbine Stop Valves) be counted and included in the pump bin. <br /> | Each pump with a rating greater than 5 hp should be counted separately (do not count pumps with a horsepower rating of 5 hp or below).<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;21. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://epri.box.com/s/mwlc5vvkmk91rwdw49tdwfh9e2ldeyq2 Description of Treatment for Pump Oil Fires (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 4)]<br /> <br /> [https://epri.box.com/s/tr6kbbgfwjveh3tfzplb1awvmxq0k8gf Fire PRA Methods Review Panel Membership (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 5)]<br /> <br /> [https://epri.box.com/s/0v6yxom7rjun3f6abvct0ww0sul87964 Panel Decision (NRC Recent Fire PRA Methods Review Panel Decisions - Attachment 6)]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052]<br /> | 2.72E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | In PWRs, the RPS MG sets are well-defined devices. <br /> | Each RPS MG set is counted separately. Electrical cabinets associated with the RPS MG set should not be counted, as they are considered to be part of the RPS MG set.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 2.31E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each indoor oil filled transformers should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | This bin includes all indoor transformers that are not an integral part of larger components. Control power transformers and other small transformers, which are subcomponents in electrical equipment, should be ignored. Examples include 4160V/480V transformers attached to AC load centers, low-voltage regulators, and essential service lighting transformers. The large yard transformers are not part of this count. <br /> | Each dry transformer with a rating greater than 45 kVa should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1] <br /> | 9.56E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.79E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | General transient combustibles or activities located in the Power Block, but not in the Control Building, Auxiliary Building, Reactor Building, Turbine Building, or Containment (PWR).<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 8.54E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | This category includes components such as air conditioning units, chillers, fan motors, air filters, dampers, etc. A fan motor and compressor housed in the same component are counted as one component. Do not count ventilation fans if the drive motor is 5 hp or less. <br /> | Each component with a rating greater than 5 HP should be counted separately.<br /> <br /> NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 extends the guidance in FAQ&amp;nbsp;07&amp;#8209;0031 to Bin&amp;nbsp;26. Totally enclosed motors should be excluded from the count because the motor housing would prevent the extension of flames outside the motor casing.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0031, Section 6 of Supplement 1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG-2178 Vol 2 / EPRI 3002016052] <br /> | 1.64E-02<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The high-voltage power transformers typically installed in the yard belong to this bin. They include plant output power transformers, auxiliary-shutdown transformers, and startup transformers, etc. Isolation phase bus ducts are also included in this bin to simplify fire frequency analysis.<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.61E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | Similar to Bin 27 this bin includes the high-voltage power transformers typically installed in the yard. However, isolation phase bus ducts are not included in this bin. <br /> In a non-catastrophic transformer failure oil does not spill outside transformer tank and the fire does not necessarily propagate beyond the fire source transformer. The analyst can use all the frequency and assume total loss of the “Transformer/Switch Yard” or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s).<br /> | Each high-voltage power transformer installed in the yard is counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 6.53E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are part of this bin. In the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the items and analysts’ judgment. <br /> | Items associated with yard transformers but not the transformers themselves (e.g., oil power output cables) are counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 3.69E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | Boilers are generally well-defined items. <br /> | Each boiler should be counted separately. All ancillary items associated with each boiler may be included as part of the boiler. Control panels that are installed separate from a boiler may be included in the “Electrical Cabinets (Plant-Wide Components)” bin.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 1.09E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | For this bin, it is assumed that all exposed cables (i.e., cables that are not in conduits or wrapped by noncombustible materials) have an equal likelihood of experiencing a fire caused by welding and cutting across the entire location (Turbine Building).<br /> | The ignition source weighting factor of cable fires caused by welding and cutting is estimated using the hot work factor and cable quantity in the fire compartment. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 16-0010. The hot work factor is then weighed in combination with a relative numerical estimate of the quantity of cables in the location to the total quantity of cables in the entire location set to generate the final location weighting factor. The cable quantity (either total weight or total combustible load) is typically reported in the Fire Hazards Analysis (FHA). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1725/ML17258A687.html FAQ 16-0010]<br /> | 3.47E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are generally well-defined entities. <br /> | Main feedwater pumps are generally well-defined entities. Ancillary components associated with each pump are considered a part of the pump and should not be counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.38E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | The turbine generator excitor is a well-defined item. Generally, there is only one excitor per unit. <br /> | Each turbine generator excitor should be counted separately.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 8.36-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. Consider the entire complex as one system and assign the ignition frequency of this bin to that system. It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for. Similar to Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and the analysts’ judgment. <br /> <br /> NOTE: It is important to have a clear definition of system boundaries to ensure that, between this bin and Bin 19, all hydrogen-carrying items of the plant are properly accounted for.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 4.12E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Similar to hydrogen, a complex of oil storage tanks, pumps, heat exchangers, valves, and control devices belong to this bin. <br /> | A complex of piping, valves, heat exchangers, oil separators, and often skid-mounted devices are associated with turbine generator hydrogen. It is recommended to treat the entire complex as one system and assign the ignition frequency of this bin to that system. Similar to the preceding bin and Bin 29, in the screening phase of the project, the analyst may conservatively assign the same frequency to all the items in this bin. If the scenario would not screen out, the frequency may then be divided among the various items using a relative ranking scheme. The ranking may be based on the relative characteristics of the items and analysts’ judgment.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> | 5.49E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | Transient fires due to hotwork activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires caused by welding and cutting is estimated using a ranking scheme that takes into account the hot work factor. The hot work ranking factors are described in Table 6-2 (as updated in FAQ 12-0064). Guidance for this bin is updated in FAQ 12-0064 Section 6.5.7.2 and Fire PRA FAQ 14-0007 (distributing transient influence factors for smaller spaces than fire compartments).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 4.67E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | General transient combustibles or activities located in the Turbine Building.<br /> | The ignition source weighting factor of transient fires is estimated using a ranking scheme that takes into account maintenance activities, occupancy level, and storage of flammable materials. These steps are outlined in FAQ 12-0064 Section 6.5.7.2. The introduction of developing transient influence factors for smaller spaces than fire compartments is discussed in FAQ 14-0007. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> <br /> [https://www.nrc.gov/docs/ML1234/ML12346A488.pdf FAQ 12-0064]<br /> <br /> [https://www.nrc.gov/docs/ML1808/ML18088B138.html FAQ 14-0007]<br /> | 6.71E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |}<br /> <br /> '''Table 6-2: Summary Description of Transient Fire Influencing Factors (as updated in FAQ 12-0064)'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Influencing Factor<br /> ! Ranking Value (Note 1)<br /> ! Where applicable<br /> |-<br /> | rowspan=&quot;6&quot;|<br /> General Electro-Mechanical (E/M) Maintenance (excluding hot work) <br /> | No (0)<br /> | Applicable for locations where maintenance activities during power operation are precluded by design and/or operation. (Note 2)<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for locations where: <br /> (1) access is strictly controlled (not just simple key-card type access) (Note 3), and <br /> <br /> (2) areas with NO equipment subject to frequent maintenance (Note 4), and<br /> <br /> (3) location contains no plant equipment or components other than cables, fire detectors, junction boxes, and other minor plant support equipment. <br /> <br /> Requirement: No violations in administrative controls (Note 5). <br /> <br /> This rating may not be applied to the MCR but may be applied to the Cable Spreading Room (CSR) devoid of other equipment, and cable vault and tunnel areas meeting the criteria. Other plant locations may also be assigned the &quot;very low&quot; (0.3) ranking factor provided all of the defined criteria are met. <br /> |-<br /> | Low (1)<br /> | Applicable for areas with small number of (preventative maintenance/corrective maintenance) PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6), or<br /> Applicable for general plant locations where strict permitting procedures are enforced, but do not meet the requirements for a “0.3” (very low) rating factor. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium (3)<br /> | Applicable for areas with average number of PM/CM work orders (Note 6). <br /> |-<br /> | High (10)<br /> | Applicable for areas with large number of PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for areas with significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | rowspan=&quot;7&quot;|<br /> Hotwork<br /> | No (0)<br /> | Applicable for areas in which hot work activities during power operation are precluded by design and/or operation (Note 2).<br /> |-<br /> | Extremely Low (0.1)<br /> | Applicable for MCR, if:<br /> (1) plant procedures prohibit hot work in the MCR during power operations, and <br /> <br /> (2) no violations in MCR hot work restrictions (Note 8). <br /> |-<br /> | Very Low (0.3)<br /> | Applicable for CSR and cable vault and tunnel areas, provided that: <br /> (1) access to the location is strictly controlled (Note 3), <br /> <br /> (2) the location contains no plant equipment or components other than cables, fire detectors, and junction boxes, <br /> <br /> (3) hot work during power operations is prohibited by plant procedures, and<br /> <br /> (4) no violations in administrative controls (Note 5)<br /> <br /> Applicable for MCR, if extremely low ranking of 0.1 is not applicable<br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> (1) Small number of hot work related PM/CM work orders associated with hot work compared to the average number of work orders for a typical compartment (Note 6). <br /> <br /> (2) General plant locations where plant procedures generally preclude hot work activities with exceptions subject to the strictest of permitting requirements. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for average number of hot work related PM/CM work orders (Note 6)<br /> |-<br /> | High (10)<br /> | Applicable for large number of hot work related PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6).<br /> |-<br /> | Very High (50)<br /> | Applicable for plant areas that may experience significantly more PM/CM work orders compared to the average number of work orders for a typical compartment (Note 6). <br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Occupancy<br /> | No (0)<br /> |Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> <br /> (1) compartments bounded on all sides by controlled physical barriers and normally unoccupied during plant operations. <br /> <br /> (2) compartments not used as an access pathway for any other plant location. <br /> <br /> (3) location with access strictly controlled (Note 3).<br /> |-<br /> | Low (1)<br /> | Applicable for compartments with low foot traffic or out of general traffic path.<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for compartments not continuously occupied, but with regular foot traffic.<br /> |-<br /> | High (10)<br /> | Applicable for continuously occupied compartments.<br /> |-<br /> | rowspan=&quot;5&quot;|<br /> Storage<br /> | No (0)<br /> | Applicable for compartments where entrance is not possible during plant operation (Note 2).<br /> |-<br /> | Very Low (0.3)<br /> | Applicable for:<br /> (1) entire fire areas designated “combustible free zones”, and<br /> <br /> (2) areas with no temporary structures built, stored or moved into the vicinity, comprised at least in part of combustible materials (e.g. wooden scaffolding). <br /> <br /> Requirement: No violations of administrative controls (Note 5). <br /> |-<br /> | Low (1)<br /> | Applicable for:<br /> <br /> (1) compartments where no combustible/flammable materials are stored by practice but where combustibles may be introduced subject to a permitting process, or <br /> <br /> (2) compartments where all combustible/flammable material are stored in closed containers and/or placed in dedicated fire-safe cabinets. <br /> <br /> Requirement: No violations in administrative controls (Note 5) OR performance monitoring program is in place (Note 7)<br /> |-<br /> | Medium or Average (3)<br /> | Applicable for areas that contain:<br /> <br /> (1) small quantities of low-combustibility materials (e.g., solid flame retardant materials) in open storage, or <br /> <br /> (2) flammable gasses or liquids stored in approved containers and/or flammable combustible storage cabinets. <br /> |-<br /> | High (10)<br /> | Applicable for compartments where: <br /> (1) combustible/flammable materials are sometimes brought in and left in either open containers for a short time or in a closed container, but outside a dedicated fire-safe cabinet for an extended time. <br /> <br /> (2) larger quantities of flammable materials (e.g., radiation protection clothing, packing boxes or materials, paints, flammable liquids, oils) are stored.<br /> |-<br /> |}<br /> <br /> '''Notes regarding Table 6-2'''<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 1: Intent of Ranking:'''<br /> The overall intent of the weighting factor method is to reflect real differences in the relative likelihood of transient fires in various locations while at the same time preserving the overall plant-wide fire frequency for each ignition source bin. In application the analyst should consider the following points relative to the intent of the transient location factor ranking method:<br /> (1) The ranking factor numerical values assigned to each location should reflect relative weighting values within each applicable frequency bin location set. The relative rankings should not look across location sets. For example, when addressing bins 36 and 37 the analyst should not compare locations of the turbine building (the location set for these two bins) to other non-turbine building locations (e.g., to areas of the control building which is covered by bin 25 and 26). <br /> (2) The full range of the numerical ranking values is available to the analyst and should, at least nominally, be exercised for each location set. If the full range of the ranking factor values is not exercised, then fire frequency will be distributed more evenly to the applicable fire compartments. If the analyst concludes that a relatively even distribution is the correct answer for the plant and location set, then it is recommended that an explanation should be provided in the PRA documentation.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 2: Access precluded by design and/or operation:''' <br /> Examples of areas where maintenance and hot work activities are precluded by design and/or operation, include the following:<br /> (1) inerted locations such as inside an inerted BWR containment during power operation,<br /> (2) very high radiation areas such as a traversing in-core probe (TIP) room (or equivalent) for a BWR,<br /> (3) permanently sealed cable tunnels such as poured concrete cable ways without access or cable tunnels where access ways have been closed by mortared block,<br /> (4) cable tunnels with manhole or hatch access where the manholes/hatches are welded shut; BUT, if an urgent situation could occur that would require cutting into the areas to avoid a shutdown, then value of 0.3 should be assigned<br /> (5) areas physically too small to allow personnel access under any conditions (e.g., an underground cable chase),<br /> (6) areas with extreme thermal environment beyond human tolerance such as the main steam tunnel in a BWR, and<br /> (7) locations where the equipment present occupies all the available space such that the storage or placement of transient materials would be physically impossible.<br /> The existence of administrative controls in and of itself is not a compelling basis for a rating of 0.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 3: Access strictly controlled:''' <br /> Examples of locations where access is strictly controlled (not just simple key-card type access) are as follows: <br /> (1) special entry permitting procedures are in place (e.g., access into containment during power operations would be an involved process),<br /> (2) confined space access controls are imposed (i.e., per OSHA requirements), <br /> (3) limited personnel access lists are established, <br /> (4) extra security controls such as locked doors with limited access keys, <br /> (5) verbal notification of entry and exit to security or operations personnel is required in a specific location,<br /> (6) entry is prohibited without health physics or radiation protection technician present,<br /> (7) entry is prohibited without a fire watch, and/or<br /> (8) personnel safety tag-outs are required to lock out an automatic suppression system (e.g., Halon or CO&lt;sub&gt;2&lt;/sub&gt;) prior to entry or prior to conducting a maintenance activity. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 4: Equipment requiring maintenance:'''<br /> Examples of equipment that do not require frequent maintenance are the following: cables, fire detectors, junction boxes and other minor plant support equipment such as normal and emergency lighting, access control panels, plant paging or communications equipment, alarms or alarm panels, and security monitoring or support equipment. <br /> In general, the presence of any piece of equipment that was counted as a fire ignition source during Step 6 would preclude assignment of “very low” for this factor. Conversely, it cannot be assumed that the lack of countable fire ignition sources implies that the very low ranking factor applies. If equipment items are present that may require maintenance but do not meet the counting criteria (e.g., smaller pumps, motors or ventilation subsystems) then the very low ranking factor would not apply. <br /> A rating of 0.3 is applicable to cable spreading rooms (CSR) devoid of other equipment, and cable vault and tunnel areas that have access strictly controlled<br /> A rating of 0.3 is not applicable for the Main Control Room. <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 5: No violations in administrative controls:''' <br /> A rating of 0.3 requires a verification that no violations of the administrative controls related to the influence factor that is being rated (maintenance, hot work, or storage) have occurred over a reasonable prior time period (i.e., five years). <br /> <br /> &lt;span style='font-size:90%&gt;'''Note 6: Work Orders:'''<br /> The analyst should use engineering judgment to determine the maintenance factor of compartments with no work orders in the selected period of time. The judgment can be based on the characteristics of the compartment relative to compartments with work orders. If the work orders cannot be collected easily, the analyst may use engineering judgment based on personal experience or information gathered from the maintenance personnel of the plant. In this case, the analyst may ask the maintenance personnel to assign a rating number between 0 and 10 in terms of frequency of maintenance at a compartment and to identify the two or three most typical maintenance activities undertaken (e.g., pump overhaul or electrical device replacement).<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 7: Performance monitoring program:'''<br /> A performance monitoring program is in place and demonstrates that the administrative control programs are meeting expectations and objectives.<br /> <br /> &lt;span style='font-size:90%&gt;'''Note 8: MCR hot work:'''<br /> The ranking of 0.1 for the MCR requires that a review of plant records confirms that no violations of, or exceptions to, the MCR hot work restrictions while at power have been recorded over some reasonable prior time period (i.e., five years).<br /> <br /> ==Supplemental Guidance==<br /> <br /> See Wiki Tables 6-1 and 6-2 for the most recent ignition source bins, counting guidance, and fire ignition frequencies.</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1214 FirePRA:Prior HEAF Guidance 2025-01-20T14:43:29Z <p>User: </p> <hr /> <div>'''Prior HEAF Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |</div> User https://firepra.epri.com/index.php?title=User:User&diff=1213 User:User 2025-01-20T14:43:12Z <p>User: User moved page User:User to FirePRA:Prior HEAF Guidance</p> <hr /> <div>#REDIRECT [[FirePRA:Prior HEAF Guidance]]</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1212 FirePRA:Prior HEAF Guidance 2025-01-20T14:43:11Z <p>User: User moved page User:User to FirePRA:Prior HEAF Guidance</p> <hr /> <div>==Prior HEAF Guidance==<br /> <br /> '''Prior HEAF Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1211 FirePRA:Prior HEAF Guidance 2025-01-20T14:37:31Z <p>User: </p> <hr /> <div>==Prior HEAF Guidance==<br /> <br /> '''Prior HEAF Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1210 FirePRA:Prior HEAF Guidance 2025-01-20T14:35:02Z <p>User: </p> <hr /> <div><br /> '''Prior HEAF Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1209 FirePRA:Prior HEAF Guidance 2025-01-20T14:33:33Z <p>User: </p> <hr /> <div>[[Prior HEAF Counting Guidance]]Prior HEAF Guidance<br /> <br /> <br /> '''Prior HEAF Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1208 FirePRA:Prior HEAF Guidance 2025-01-20T14:24:59Z <p>User: </p> <hr /> <div>Prior HEAF Guidance<br /> <br /> <br /> '''Prior HEAF Fire Ignition Sources, Counting Guidance, and Ignition Frequencies'''<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Description<br /> ! Count (how)<br /> ! Counting Reference<br /> ! Fire Ignition Frequency (Mean)<br /> ! Fire Ignition Frequency Reference<br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers operating between 480 and 1000 Volts. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. <br /> | Each vertical segment of the switchgear and load center for low voltage (480-1000 V) electrical cabinets is counted separately. MCCs are not included, unless the MCC is associated with switchgear that is used directly to operate equipment such as load centers. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 1.52E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | High-energy arcing faults are associated with switchgear and load centers. Switchyard transformers and isolation phase buses are not part of this bin. For this bin, similar to electrical cabinets, the vertical segments of the switchgear and load centers should be counted. Additionally, to cover potential explosive failure of oil filled transformers (those transformers that are associated with 4.16 or 6.9kV switchgear and load centers) may be included in vertical segment counts of the switchgear. <br /> | Each vertical segment of the switchgear and load center for medium voltage (above 1000 V) electrical cabinets is counted separately. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI 1011989 / NUREG/CR-6850]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 06-0017, Section 4 of Supplement 1]<br /> | 2.13E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | A bus duct where the bus bars are made up of multiple sections bolted together at regular intervals (transition points). Here, the bus bars are contained within open-ended sections of metal covers that are bolted together to form a continuous grounded enclosure running the full distance between termination points.<br /> Segmented bus ducts are able to accommodate tap connections to supply multiple equipment termination points.<br /> – Segmented bus ducts tend to be longer in comparison to the nonsegmented bus ducts. Segmented bus ducts are used in cases where the required lengths and/or geometries<br /> make the use of nonsegmented bus ducts impractical.<br /> – The length of each segment may vary depending on supplier and installation details.<br /> – Segmented bus ducts tend to connect end devices that are remote from each other. Example: A segmented bus duct might be used to connect an oil-filled transformer<br /> located in an outdoor area to equipment (e.g., switchgear) located inside the plant buildings.<br /> <br /> Note: This bin does not cover nonsegmented or continuous bus ducts or cable ducts. The arc faults for these two categories are inherently included in the treatment of the end device, and no further treatment is needed. <br /> | The analyst will need to choose between one of two recommended practices for counting segmented bus ducts as a fire ignition source. The choice will be dependent on whether or not the transition points can be identified based on an external visual inspection of the bus duct. <br /> <br /> Counting approach 1: If the transition points along the length of the segmented bus duct can be identified by external visual inspection, or based on plant electrical construction drawings, then<br /> count the total number of transition points. Note that transition point counting excludes the bus end termination points, which are considered a part of the end device for fire frequency purposes.<br /> Transition points may be identifiable based on visual observation or review of design drawings. Transition points for the bus bars may, or may not, correspond to junctions in the outer ducting<br /> that surrounds the bus bars. It is not intended that the protective duct be removed to identify transition points.<br /> <br /> However, industry feedback indicates that the joints or junctions in the outer ducting surrounding a bus duct cannot be assumed to correspond to junctions in the bus bars themselves without<br /> confirmation. A representative sample of plant applications should be inspected to ensure that the internal bus bar transition points and external duct junctions do in fact align with each other.<br /> Once the total count of transition points has been obtained, the plant-wide fire frequency is then partitioned to a specific location based on the number of transition points in the location of<br /> interest divided by the total number of transition points for the entire plant.<br /> <br /> Counting approach 2: If the transition points cannot be identified based on external visual inspection, or by plant electrical construction drawings, then the partitioning of fire frequency to<br /> a specific fire scenario is based on apportioning of the fire frequency equally along the length of the bus duct. Hence, the analysis must estimate the total length of segmented bus duct present in<br /> the plant under analysis. A “per linear foot” fire frequency can then be estimated by dividing the plant-wide fire frequency by the total length of segmented bus duct in the plant.<br /> <br /> That is, the fire frequency for a given fire scenario would be based on the ratio of the length of duct for which identified targets fall within the bus duct arc fault zone of influence to the total length of bus duct in the plant. A lower limit to the assumed fire frequency for any given fire scenario is also applied.<br /> That is, if the length of bus duct for which the identified target(s) fall within the zone of influence is less than 12 linear feet, then a minimum length of 12 feet should be assumed. This<br /> lower bound is based on the assumption that, lacking specific information on segment lengths, a nominal segment length of 12 feet should be assumed. Any single scenario is then assigned a fire<br /> frequency equivalent to that associated with one bus bar segment 12 feet in length (i.e., equivalent to one nominal transition point).<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 1.10E-03<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | A bus duct where the bus bars for each phase are separately enclosed in their own protective housing. The use of iso-phase buses is generally limited to the bus work connecting the main generator to the main transformer.<br /> | There should generally be one iso-phase bus per unit (an iso-phase bus includes all three phases). If there is more than one iso-phase bus, simply count the total number of iso-phases buses per unit. For individual fire scenarios, the plant-wide frequency is applied (i.e. partitioned) equally to each end of each iso-phase bus duct counted. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section 7 of Supplement 1]<br /> | 5.91E-04<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en EPRI 3002002936 (NUREG-2169)]<br /> |</div> User https://firepra.epri.com/index.php?title=FirePRA:Prior_HEAF_Guidance&diff=1207 FirePRA:Prior HEAF Guidance 2025-01-20T14:20:05Z <p>User: Created page with &quot;Prior HEAF Guidance&quot;</p> <hr /> <div>Prior HEAF Guidance</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1206 Detailed Fire Modeling (Task 11) 2024-12-11T02:15:30Z <p>User: </p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> EPRI FIVE<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 576<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | 0.025<br /> | style=&quot;text-align: center;&quot; | 0.038<br /> | [https://www.epri.com/research/products/000000003002025942 NUREG-2262]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].<br /> <br /> In 2024, EPRI and the NRC updated the alpha and pi parameters of the NUREG-2180 event tree in [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]. Additionally, NUREG-2180 Supplement 1 Section 5 provides guidance on how to use NUREG-2180 with the framework in NUREG-2230. In summary, the concepts in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230] (interruptible fires) and NUREG-2180 (pre-flaming conditions) are considered independent. <br /> <br /> Table 4-2, reproduced below provide the most recent alpha factors from NUREG-2180.<br /> {| class=wikitable<br /> |+ style=&quot;text-align: left;&quot; | Fraction of fires in NUREG-2180 Supp. 1 that do not have an incipient phase<br /> |-<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Category<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Mean Alpha Fraction (5&lt;sup&gt;th&lt;/sup&gt;/95&lt;sup&gt;th&lt;/sup&gt;)<br /> |-<br /> |-<br /> | style=&quot;text-align: center;&quot; | Power cabinets<br /> | style=&quot;text-align: center;&quot; | 0.41 (0.30/0.53)<br /> |-<br /> | style=&quot;text-align: center;&quot; | Low-voltage control cabinets<br /> | style=&quot;text-align: center;&quot; | 0.10 (0.01/0.25)<br /> |}<br /> <br /> For enhanced suppression, Table 4-3 and Table 4-5 in NUREG-2180 Supplement 1 provide the enhanced suppression rates which are summarized in the table below:<br /> <br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: left;&quot; | Enhanced Suppression Rates for Incipient Detection, λ<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 5&lt;sup&gt;th&lt;/sup&gt; percent<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 50&lt;sup&gt;th&lt;/sup&gt; percent<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 95&lt;sup&gt;th&lt;/sup&gt; percent <br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | NSP Reference<br /> |-<br /> | &amp;pi;&lt;sub&gt;1&lt;/sub&gt; In-cabinet enhanced suppression (using the Control room suppression curve)<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | &amp;pi;&lt;sub&gt;2&lt;/sub&gt; Area-wide, enhanced suppression <br /> | style=&quot;text-align: center;&quot; | 0.226<br /> | style=&quot;text-align: center;&quot; | 0.131<br /> | style=&quot;text-align: center;&quot; | 0.220<br /> | style=&quot;text-align: center;&quot; | 0.344<br /> | [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]<br /> |}</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1205 Detailed Fire Modeling (Task 11) 2024-12-11T02:11:46Z <p>User: </p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> EPRI FIVE<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 576<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | 0.025<br /> | style=&quot;text-align: center;&quot; | 0.038<br /> | [https://www.epri.com/research/products/000000003002025942 NUREG-2262]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> &lt;div id=&quot;028Note&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#028|^]] ''[https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ 17-0013] reported the 50th percentile as 0.029. When calculated using the chi-squared distribution the calculated 50th percentile 0.028 as shown in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230].''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].<br /> <br /> In 2024, EPRI and the NRC updated the alpha and pi parameters of the NUREG-2180 event tree in [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]. Additionally, NUREG-2180 Supplement 1 Section 5 provides guidance on how to use NUREG-2180 with the framework in NUREG-2230. In summary, the concepts in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230] (interruptible fires) and NUREG-2180 (pre-flaming conditions) are considered independent. <br /> <br /> Table 4-2, reproduced below provide the most recent alpha factors from NUREG-2180.<br /> {| class=wikitable<br /> |+ style=&quot;text-align: left;&quot; | Fraction of fires in NUREG-2180 Supp. 1 that do not have an incipient phase<br /> |-<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Category<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Mean Alpha Fraction (5&lt;sup&gt;th&lt;/sup&gt;/95&lt;sup&gt;th&lt;/sup&gt;)<br /> |-<br /> |-<br /> | style=&quot;text-align: center;&quot; | Power cabinets<br /> | style=&quot;text-align: center;&quot; | 0.41 (0.30/0.53)<br /> |-<br /> | style=&quot;text-align: center;&quot; | Low-voltage control cabinets<br /> | style=&quot;text-align: center;&quot; | 0.10 (0.01/0.25)<br /> |}<br /> <br /> For enhanced suppression, Table 4-3 and Table 4-5 in NUREG-2180 Supplement 1 provide the enhanced suppression rates which are summarized in the table below:<br /> <br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: left;&quot; | Enhanced Suppression Rates for Incipient Detection, λ<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 5&lt;sup&gt;th&lt;/sup&gt; percent<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 50&lt;sup&gt;th&lt;/sup&gt; percent<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 95&lt;sup&gt;th&lt;/sup&gt; percent <br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | NSP Reference<br /> |-<br /> | &amp;pi;&lt;sub&gt;1&lt;/sub&gt; In-cabinet enhanced suppression (using the Control room suppression curve)<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | &amp;pi;&lt;sub&gt;2&lt;/sub&gt; Area-wide, enhanced suppression <br /> | style=&quot;text-align: center;&quot; | 0.226<br /> | style=&quot;text-align: center;&quot; | 0.131<br /> | style=&quot;text-align: center;&quot; | 0.220<br /> | style=&quot;text-align: center;&quot; | 0.344<br /> | [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]<br /> |}</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1204 Detailed Fire Modeling (Task 11) 2024-12-11T01:49:44Z <p>User: </p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> EPRI FIVE<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 11<br /> | style=&quot;text-align: center;&quot; | 385<br /> | style=&quot;text-align: center;&quot; | 0.029<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | &lt;div id=&quot;028&quot;&gt;&lt;/div&gt;0.028[[#028Note|&lt;sup&gt;^&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 0.044<br /> | [https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ&amp;nbsp;17&amp;#8209;0013]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> &lt;div id=&quot;028Note&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#028|^]] ''[https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ 17-0013] reported the 50th percentile as 0.029. When calculated using the chi-squared distribution the calculated 50th percentile 0.028 as shown in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230].''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].<br /> <br /> In 2024, EPRI and the NRC updated the alpha and pi parameters of the NUREG-2180 event tree in [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]. Additionally, NUREG-2180 Supplement 1 Section 5 provides guidance on how to use NUREG-2180 with the framework in NUREG-2230. In summary, the concepts in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230] (interruptible fires) and NUREG-2180 (pre-flaming conditions) are considered independent. <br /> <br /> Table 4-2, reproduced below provide the most recent alpha factors from NUREG-2180.<br /> {| class=wikitable<br /> |+ style=&quot;text-align: left;&quot; | Fraction of fires in NUREG-2180 Supp. 1 that do not have an incipient phase<br /> |-<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Category<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Mean Alpha Fraction (5&lt;sup&gt;th&lt;/sup&gt;/95&lt;sup&gt;th&lt;/sup&gt;)<br /> |-<br /> |-<br /> | style=&quot;text-align: center;&quot; | Power cabinets<br /> | style=&quot;text-align: center;&quot; | 0.41 (0.30/0.53)<br /> |-<br /> | style=&quot;text-align: center;&quot; | Low-voltage control cabinets<br /> | style=&quot;text-align: center;&quot; | 0.10 (0.01/0.25)<br /> |}<br /> <br /> For enhanced suppression, Table 4-3 and Table 4-5 in NUREG-2180 Supplement 1 provide the enhanced suppression rates which are summarized in the table below:<br /> <br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: left;&quot; | Enhanced Suppression Rates for Incipient Detection, λ<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 5&lt;sup&gt;th&lt;/sup&gt; percent<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 50&lt;sup&gt;th&lt;/sup&gt; percent<br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | 95&lt;sup&gt;th&lt;/sup&gt; percent <br /> ! rowspan=&quot;1&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | NSP Reference<br /> |-<br /> | &amp;pi;&lt;sub&gt;1&lt;/sub&gt; In-cabinet enhanced suppression (using the Control room suppression curve)<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | &amp;pi;&lt;sub&gt;2&lt;/sub&gt; Area-wide, enhanced suppression <br /> | style=&quot;text-align: center;&quot; | 0.226<br /> | style=&quot;text-align: center;&quot; | 0.131<br /> | style=&quot;text-align: center;&quot; | 0.220<br /> | style=&quot;text-align: center;&quot; | 0.344<br /> | [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]<br /> |}</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1203 Detailed Fire Modeling (Task 11) 2024-12-11T01:19:35Z <p>User: </p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> EPRI FIVE<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 11<br /> | style=&quot;text-align: center;&quot; | 385<br /> | style=&quot;text-align: center;&quot; | 0.029<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | &lt;div id=&quot;028&quot;&gt;&lt;/div&gt;0.028[[#028Note|&lt;sup&gt;^&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 0.044<br /> | [https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ&amp;nbsp;17&amp;#8209;0013]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> &lt;div id=&quot;028Note&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#028|^]] ''[https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ 17-0013] reported the 50th percentile as 0.029. When calculated using the chi-squared distribution the calculated 50th percentile 0.028 as shown in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230].''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].<br /> <br /> In 2024, EPRI and the NRC updated the alpha and pi parameters of the NUREG-2180 event tree in [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]. Additionally, NUREG-2180 Supplement 1 provided guidance on how to use NUREG-2180 with the framework in NUREG-2230.Table 4-2, reproduced below provide the most recent alpha factors from NUREG-2180.<br /> {| class=wikitable<br /> |+ style=&quot;text-align: left;&quot; | Fraction of fires in NUREG-2180 Supp. 1 that do not have an incipient phase<br /> |-<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Category<br /> ! scope=&quot;col&quot; style=&quot;width: 250px;&quot; | Mean Alpha Fraction (5&lt;sup&gt;th&lt;/sup&gt;/95&lt;sup&gt;th&lt;/sup&gt;)<br /> |-<br /> |-<br /> | style=&quot;text-align: center;&quot; | Power cabinets<br /> | style=&quot;text-align: center;&quot; | 0.41 (0.30/0.53)<br /> |-<br /> | style=&quot;text-align: center;&quot; | Low-voltage control cabinets<br /> | style=&quot;text-align: center;&quot; | 0.10 (0.01/0.25)<br /> |}</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1202 Detailed Fire Modeling (Task 11) 2024-12-11T01:03:13Z <p>User: </p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> EPRI FIVE<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 11<br /> | style=&quot;text-align: center;&quot; | 385<br /> | style=&quot;text-align: center;&quot; | 0.029<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | &lt;div id=&quot;028&quot;&gt;&lt;/div&gt;0.028[[#028Note|&lt;sup&gt;^&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 0.044<br /> | [https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ&amp;nbsp;17&amp;#8209;0013]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> &lt;div id=&quot;028Note&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#028|^]] ''[https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ 17-0013] reported the 50th percentile as 0.029. When calculated using the chi-squared distribution the calculated 50th percentile 0.028 as shown in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230].''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].<br /> <br /> In 2024, EPRI and the NRC updated the alpha and pi parameters of the NUREG-2180 event tree in [https://www.epri.com/research/products/000000003002028821 NUREG-2180 Supplement 1]. Additionally, NUREG-2180 Supplement 1 provided guidance on how to use NUREG-2180 with the framework in NUREG-2230.</div> User https://firepra.epri.com/index.php?title=MediaWiki:Common.js&diff=1201 MediaWiki:Common.js 2023-09-08T18:32:49Z <p>User: </p> <hr /> <div>/* Any JavaScript here will be loaded for all users on every page load. */<br /> $(document).ready(function() {<br /> var gscript = document.createElement( 'script' );<br /> gscript.setAttribute( 'src', 'https://www.googletagmanager.com/gtag/js?id=G-5V1LKDM2DY' );<br /> gscript.async = true;<br /> $(&quot;head&quot;).append(gscript);<br /> var gscript2 = document.createElement( 'script' );<br /> gscript2.innerHTML = &quot;window.dataLayer = window.dataLayer || [];&quot; + &quot;\n&quot; +<br /> &quot;function gtag(){dataLayer.push(arguments);}&quot; + &quot;\n&quot; +<br /> &quot;gtag('js', new Date());&quot; + &quot;\n&quot; +<br /> &quot;gtag('config', 'G-5V1LKDM2DY')\;&quot; ;<br /> $(&quot;head&quot;).append(gscript2);<br /> });</div> User https://firepra.epri.com/index.php?title=MediaWiki:Common.js&diff=1200 MediaWiki:Common.js 2023-06-28T21:48:02Z <p>User: Created page with &quot;/* Any JavaScript here will be loaded for all users on every page load. */ $(document).ready(function() { var pageBase = document.getElementById('content'); pageBase.innerHTML...&quot;</p> <hr /> <div>/* Any JavaScript here will be loaded for all users on every page load. */<br /> $(document).ready(function() {<br /> var pageBase = document.getElementById('content');<br /> pageBase.innerHTML = pageBase.innerHTML + &quot;\n&quot; + &quot;&lt;!-- Google tag (gtag.js) --&gt; &lt;script async src=\&quot;https://www.googletagmanager.com/gtag/js?id=G-5V1LKDM2DY\&quot;&gt;&lt;/script&gt; &lt;script&gt; window.dataLayer = window.dataLayer || []; function gtag(){dataLayer.push(arguments);} gtag('js', new Date()); gtag('config', 'G-5V1LKDM2DY'); &lt;/script&gt;&quot;;<br /> <br /> });</div> User https://firepra.epri.com/index.php?title=MediaWiki:Sidebar&diff=1199 MediaWiki:Sidebar 2022-05-03T18:04:21Z <p>User: </p> <hr /> <div><br /> * navigation<br /> ** Fire_PRA_Methodology|Fire PRA Methodology<br /> ** Plant_Boundary_Definition_and_Partitioning_(Task_1)|Plant Boundary Definition and Partitioning (Task 1)<br /> ** Fire_PRA_Component_Selection_(Task_2)|Fire PRA Component Selection (Task 2)<br /> ** Fire_PRA_Cable_Selection_(Task 3)|Fire PRA Cable Selection (Task 3)<br /> ** Qualitative Screening (Task 4)|Qualitative Screening (Task 4)<br /> ** Plant_Fire-Induced_Risk_Model_(Task_5)|Plant Fire-Induced Risk Model (Task 5)<br /> ** Fire_Ignition_Frequency_(Task_6)|Fire Ignition Frequency (Task 6)<br /> ** Quantitative_Screening_(Task_7)|Quantitative Screening (Task 7)<br /> ** Scoping_Fire_Modeling_(Task_8)|Scoping Fire Modeling (Task 8)<br /> ** Detailed_Circuit_Failure_Analysis_(Task_9)|Detailed Circuit Failure Analysis (Task 9)<br /> ** Circuit_Failure_Mode_Likelihood_Analysis_(Task_10)|Circuit Failure Mode Likelihood Analysis (Task 10)<br /> ** Detailed_Fire_Modeling_(Task_11)|Detailed Fire Modeling (Task 11)<br /> ** Post-Fire_Human_Reliability_Analysis_(Task_12)|Post-Fire Human Reliability Analysis (Task 12)<br /> ** Seismic_Fire_Interactions_(Task_13)|Seismic Fire Interactions (Task 13)<br /> ** Fire_Risk_Quantification_(Task_14)|Fire Risk Quantification (Task 14)<br /> ** Uncertainty_and_Sensitivity_Analyses_(Task_15)|Uncertainty and Sensitivity Analyses (Task 15)<br /> ** Fire_PRA_Documentation_(Task_16)|Fire PRA Documentation (Task 16)<br /> ** Technology_Transfer|Technology Transfer<br /> * Feedback<br /> ** mailto:crochon@epri.com?subject=FirePRA_Wiki|Send Feedback</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Cable_Selection_(Task_3)&diff=1198 Fire PRA Cable Selection (Task 3) 2021-11-12T13:58:31Z <p>User: /* NEI&amp;nbsp;00&amp;#8209;01 */</p> <hr /> <div>==Task Overview==<br /> <br /> === Background ===<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. This document offers a more structured set of rules for selection of cables.<br /> <br /> === Purpose ===<br /> Conducting a Fire PRA in accordance with this procedure necessitates an analysis of fire-induced circuit failures beyond that typically conducted during original Fire PRAs. The circuit analysis elements of the project are conducted in three distinct phases: <br /> <br /> * Fire PRA cable selection (Task 3), <br /> * Detailed circuit failure analysis ([https://firepra.epri.com/index.php?title=Detailed_Circuit_Failure_Analysis_(Task_9) Task 9]), and<br /> * Circuit failure mode likelihood analysis ([https://firepra.epri.com/index.php?title=Circuit_Failure_Mode_Likelihood_Analysis_(Task_10) Task 10]).<br /> <br /> This task provides methods and instructions for conducting the first phase of circuit analysis–selecting Fire PRA cables (Task 3). The purpose of Task 3 is to identify for all Fire PRA components the circuits/cables associated with the components and the routing/plant location of the identified circuits/cables. These relationships can then be used to determine the Fire PRA components potentially affected by postulated fires at different plant locations. <br /> <br /> In most cases, it is advantageous to perform some or all of Task 9 (detailed circuit failure analysis) coincident with Task 3. The degree to which Task 3 and Task 9 are combined is highly dependent on numerous plant-specific factors. Considerations for combining the two tasks are incorporated in relevant sections of Chapter 3.<br /> <br /> === Scope ===<br /> Task 3 provides methods and technical considerations for identifying cables to be included in the Fire PRA Cable List. This task contains the following key elements: <br /> <br /> * Identify cables associated with Fire PRA equipment, <br /> * Determine plant routing and location for the Fire PRA cables,<br /> * Identify Fire PRA power supplies, and<br /> * Correlate Fire PRA cables to Fire PRA equipment and plant locations (fire compartments and/or fire areas). <br /> <br /> Implementation of plant-specific quality assurance and configuration control requirements that might apply to a Fire PRA is not within the scope of this task. Nor does this task address validating the accuracy of plant-specific data extracted from plant drawings, documents, or databases. Each plant should follow appropriate quality assurance, administrative, and configuration control procedures applicable to the work conducted. The need to validate input source documents should be addressed as part of assembling the prerequisite information.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Cable Selection and Location (CS)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix B, Appendix for Chapter 3, Example<br /> <br /> Appendix I, Appendix for Chapter 9, Examples of Components Circuits Analysis<br /> <br /> ==Supplemental Guidance==<br /> <br /> ===[https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01]===<br /> NEI&amp;nbsp;00&amp;#8209;01 documents the cable selection and circuit analysis processes as well as the criteria for deterministic analyses and Fire PRAs. <br /> * Parts of [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;2] are endorsed in NRC [https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML17340A875 RG&amp;#8209;1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;3] February&amp;nbsp;2018.<br /> * [https://www.nrc.gov/docs/ML1935/ML19351D273.html NEI 00-01 Revision 4] was issued in December 2019 to include the topics addressed in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]. Parts of the NEI 00-01 revision, including the content from EPRI 3002009214 / NUREG/CR 7150 Volume 3, are endorsed in [https://www.nrc.gov/docs/ML2104/ML21048A441.pdf RG 1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;4] May 2021.<br /> <br /> ===Fire-Induced Spurious Operations===<br /> <br /> Additionally, since the publication of NUREG/CR-6850, significant research on fire-induced spurious operations has occurred. This has resulted in the publication of three EPRI/NRC reports on this subject. <br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Phenomena Identification and Ranking Table (PIRT) Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000000001026424/ EPRI&amp;nbsp;1026424 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;1])====<br /> This report documents a Phenomena Identification and Ranking Table (PIRT) exercise on fire-induced electrical circuit failures that may occur in nuclear power plants as a result of fire damage to cables. The results and conclusions of the PIRT panel are a primary input to the follow on PRA Expert Panel documented in Volume 2.<br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* The spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible.<br /> :* The spurious operation of DC compound-wound motor due to proper polarity hot shorts in the motive/power cabling is incredible.<br /> :* The ignition of a secondary fire from an open circuited CT secondary circuit with a turns ratio of 1200:5 or less is incredible (Note: This is later modified and clarified in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]).<br /> :* The guidance given in Nuclear Energy Institute, [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI 00-01, Rev. 2], Appendix B.1, can be applied safely to fire safe-shutdown methodologies throughout the plant in resolving concerns associated with Multiple High-Impedance Faults (MHIFs). (Note: Appendix B.1 of NEI 00-01, Rev. 2 offers a basis for concluding that MHIFs need not be considered provided there exists breaker coordination for any circuits damaged by the fire that should previously have been assessed for the effects of MHIFs and appropriate testing and maintenance is performed)<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Expert Elicitation Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000003002001989/ EPRI&amp;nbsp;3002001989 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;2])====<br /> This report documents the results of the PRA panel's expert elicitation that is used to develop the conditional probabilities of hot-short induced spurious operation &amp; duration of various control circuit configurations.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* A new failure mode, the Ground Fault Equivalent Hot Short (GFEHS) has been identified. A GFEHS occurs when fire damage results in conductors of the same or different cable developing a relatively low impedance fault with a ground plane. For the GFEHS to cause a hot short induced spurious operation, both a source and target conductor must short to the same ground plane and have a compatible power supply. Source conductors are those which can supply energy (voltage, current). Target conductors are associated with end devices such as a conductor connected to a solenoid or a conductor connected to a contactor of a motor starter.<br /> :** Spurious operation caused by shorting conductors through a surrogate ground path in ungrounded circuits as a result of fire induced damage, is a failure mode which occurred during the [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7100// DESIREE-Fire testing] and is referred to as “Ground Fault Equivalent Hot Short.” The probability of this failure mechanism with respect to cable-to-cable hot shorts is such that it warrants consideration for including in future testing programs and, subsequently, in analyzing post-fire safe-shutdown conditions.<br /> :*Conditional probabilities and spurious operation duration are covered in Task 10.<br /> <br /> :'''NRC Correspondence'''<br /> :* NRC Memo dated June 14, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1316/ML13165A209.pdf ML13165A209], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC letter to NEI, dated December 16, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1323/ML13238A280.pdf ML13238A280], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC Memo dated February 12, 2014, Supplemental Interim Technical Guidance on Fireinduced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1401/ML14017A091.pdf ML14017A091])<br /> :* NRC letter to NEI, dated April 23, 2014, Supplemental Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1408/ML14086A165.pdf ML14086A165])<br /> :(The memos and letters dated June 14, 2013, December 16, 2013, February 12, 2014, and April 23, 2014 referenced interim guidance until the issuance of NUREG/CR-7150, Volume 2, in May 2014. '''NUREG/CR-7150, Vol. 2 should be referred to as the official guidance. The purpose of the memos and letters is to trace NRC acceptance of the guidance.''')<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure ([https://www.epri.com/#/pages/product/000000003002009214/ EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3])====<br /> <br /> This report provides technical recommendations to resolve long-standing issues related to evaluation of multiple spurious operations and deterministic post-fire safe shutdown analyses. Note that the approaches and content from EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3 was incorporated into NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;4 and endorsed by the NRC in RG&amp;nbsp;1.189 Revision&amp;nbsp;4.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :*Clarified circuit failure modes and terminology including: proper polarity, latching versus non-latching, high impact components, failure mode classification and GFEHS<br /> :*Revised several PIRT panel positions following the conclusions of the PRA Expert Panel<br /> :**Consideration of insulation type for the aggressor cable conductor is eliminated. This was eliminated due to the impracticality of tracking the conductor insulation for aggressor cables. As a result, the reported classifications are a function of the conductor insulation of the target conductor.<br /> :**Classification of inter-cable hot shorts for thermoset insulated conductors from &quot;implausible&quot; to &quot;plausible&quot; based on the PRA expert panel probabilities that did not support a classification of &quot;implausible&quot;<br /> :**Grouped single break ungrounded AC (from common CPT or distributed) with DC due to similarities in circuit failure type classification. <br /> :**Classified inter-cable hot shorts for double break design with TP insulated conductors as &quot;implausible&quot; for latching and &quot;incredible&quot; for non-latching circuits. This classification was deferred until the PRA Expert Panel completed their estimation. <br /> :*Developed technical design considerations for shorting switch applications<br /> :*Disposition of secondary fires due to a fire-induced open circuited current transformer<br /> :**Testing is documented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7228// NUREG/CR-7228, ''Open Secondary Testing of Window-Type Current Transformers'']<br /> <br /> ===Methodology for Modeling Plant Trip Probabilities in Nuclear Power Plant Fire Probabilistic Risk Assessment ([https://www.epri.com/#/pages/product/3002016053/ EPRI&amp;nbsp;3002016053])===<br /> Typically, a Fire PRA assumes a reactor trip for fire scenarios unless it can be demonstrated that no Fire PRA components are impacted and the reactor will not trip. As a result, very few Fire PRA scenarios are screened from quantification. The operating experience in the United States was reviewed and showed that only one in six events results in a plant trip, and the events are strongly correlated with a few ignition source bins mainly related to electrical distribution and the turbine generator. This report documents a methodology and screening process that can be applied to fire scenarios for ignition source bins where a plant trip is unlikely to occur. For qualifying scenarios, a 0.1 conditional trip probability can be applied.</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Cable_Selection_(Task_3)&diff=1197 Fire PRA Cable Selection (Task 3) 2021-11-12T13:47:53Z <p>User: /* Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure (EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3) */</p> <hr /> <div>==Task Overview==<br /> <br /> === Background ===<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. This document offers a more structured set of rules for selection of cables.<br /> <br /> === Purpose ===<br /> Conducting a Fire PRA in accordance with this procedure necessitates an analysis of fire-induced circuit failures beyond that typically conducted during original Fire PRAs. The circuit analysis elements of the project are conducted in three distinct phases: <br /> <br /> * Fire PRA cable selection (Task 3), <br /> * Detailed circuit failure analysis ([https://firepra.epri.com/index.php?title=Detailed_Circuit_Failure_Analysis_(Task_9) Task 9]), and<br /> * Circuit failure mode likelihood analysis ([https://firepra.epri.com/index.php?title=Circuit_Failure_Mode_Likelihood_Analysis_(Task_10) Task 10]).<br /> <br /> This task provides methods and instructions for conducting the first phase of circuit analysis–selecting Fire PRA cables (Task 3). The purpose of Task 3 is to identify for all Fire PRA components the circuits/cables associated with the components and the routing/plant location of the identified circuits/cables. These relationships can then be used to determine the Fire PRA components potentially affected by postulated fires at different plant locations. <br /> <br /> In most cases, it is advantageous to perform some or all of Task 9 (detailed circuit failure analysis) coincident with Task 3. The degree to which Task 3 and Task 9 are combined is highly dependent on numerous plant-specific factors. Considerations for combining the two tasks are incorporated in relevant sections of Chapter 3.<br /> <br /> === Scope ===<br /> Task 3 provides methods and technical considerations for identifying cables to be included in the Fire PRA Cable List. This task contains the following key elements: <br /> <br /> * Identify cables associated with Fire PRA equipment, <br /> * Determine plant routing and location for the Fire PRA cables,<br /> * Identify Fire PRA power supplies, and<br /> * Correlate Fire PRA cables to Fire PRA equipment and plant locations (fire compartments and/or fire areas). <br /> <br /> Implementation of plant-specific quality assurance and configuration control requirements that might apply to a Fire PRA is not within the scope of this task. Nor does this task address validating the accuracy of plant-specific data extracted from plant drawings, documents, or databases. Each plant should follow appropriate quality assurance, administrative, and configuration control procedures applicable to the work conducted. The need to validate input source documents should be addressed as part of assembling the prerequisite information.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Cable Selection and Location (CS)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix B, Appendix for Chapter 3, Example<br /> <br /> Appendix I, Appendix for Chapter 9, Examples of Components Circuits Analysis<br /> <br /> ==Supplemental Guidance==<br /> <br /> ===[https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01]===<br /> NEI&amp;nbsp;00&amp;#8209;01 documents the cable selection and circuit analysis processes as well as the criteria for deterministic analyses and Fire PRAs. <br /> * Parts of [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;2] are endorsed in NRC [https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML17340A875 RG&amp;#8209;1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;3] February&amp;nbsp;2018<br /> * [https://www.nrc.gov/docs/ML1935/ML19351D273.html NEI 00-01 Revision 4] was issued in December 2019 to include the topics addressed in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]. Parts of the NEI 00-01 revision, including the content from EPRI 3002009214 / NUREG/CR 7150 Volume 3, are endorsed in [https://www.nrc.gov/docs/ML2104/ML21048A441.pdf RG 1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;4] May 2021.<br /> <br /> ===Fire-Induced Spurious Operations===<br /> <br /> Additionally, since the publication of NUREG/CR-6850, significant research on fire-induced spurious operations has occurred. This has resulted in the publication of three EPRI/NRC reports on this subject. <br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Phenomena Identification and Ranking Table (PIRT) Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000000001026424/ EPRI&amp;nbsp;1026424 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;1])====<br /> This report documents a Phenomena Identification and Ranking Table (PIRT) exercise on fire-induced electrical circuit failures that may occur in nuclear power plants as a result of fire damage to cables. The results and conclusions of the PIRT panel are a primary input to the follow on PRA Expert Panel documented in Volume 2.<br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* The spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible.<br /> :* The spurious operation of DC compound-wound motor due to proper polarity hot shorts in the motive/power cabling is incredible.<br /> :* The ignition of a secondary fire from an open circuited CT secondary circuit with a turns ratio of 1200:5 or less is incredible (Note: This is later modified and clarified in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]).<br /> :* The guidance given in Nuclear Energy Institute, [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI 00-01, Rev. 2], Appendix B.1, can be applied safely to fire safe-shutdown methodologies throughout the plant in resolving concerns associated with Multiple High-Impedance Faults (MHIFs). (Note: Appendix B.1 of NEI 00-01, Rev. 2 offers a basis for concluding that MHIFs need not be considered provided there exists breaker coordination for any circuits damaged by the fire that should previously have been assessed for the effects of MHIFs and appropriate testing and maintenance is performed)<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Expert Elicitation Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000003002001989/ EPRI&amp;nbsp;3002001989 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;2])====<br /> This report documents the results of the PRA panel's expert elicitation that is used to develop the conditional probabilities of hot-short induced spurious operation &amp; duration of various control circuit configurations.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* A new failure mode, the Ground Fault Equivalent Hot Short (GFEHS) has been identified. A GFEHS occurs when fire damage results in conductors of the same or different cable developing a relatively low impedance fault with a ground plane. For the GFEHS to cause a hot short induced spurious operation, both a source and target conductor must short to the same ground plane and have a compatible power supply. Source conductors are those which can supply energy (voltage, current). Target conductors are associated with end devices such as a conductor connected to a solenoid or a conductor connected to a contactor of a motor starter.<br /> :** Spurious operation caused by shorting conductors through a surrogate ground path in ungrounded circuits as a result of fire induced damage, is a failure mode which occurred during the [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7100// DESIREE-Fire testing] and is referred to as “Ground Fault Equivalent Hot Short.” The probability of this failure mechanism with respect to cable-to-cable hot shorts is such that it warrants consideration for including in future testing programs and, subsequently, in analyzing post-fire safe-shutdown conditions.<br /> :*Conditional probabilities and spurious operation duration are covered in Task 10.<br /> <br /> :'''NRC Correspondence'''<br /> :* NRC Memo dated June 14, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1316/ML13165A209.pdf ML13165A209], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC letter to NEI, dated December 16, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1323/ML13238A280.pdf ML13238A280], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC Memo dated February 12, 2014, Supplemental Interim Technical Guidance on Fireinduced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1401/ML14017A091.pdf ML14017A091])<br /> :* NRC letter to NEI, dated April 23, 2014, Supplemental Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1408/ML14086A165.pdf ML14086A165])<br /> :(The memos and letters dated June 14, 2013, December 16, 2013, February 12, 2014, and April 23, 2014 referenced interim guidance until the issuance of NUREG/CR-7150, Volume 2, in May 2014. '''NUREG/CR-7150, Vol. 2 should be referred to as the official guidance. The purpose of the memos and letters is to trace NRC acceptance of the guidance.''')<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure ([https://www.epri.com/#/pages/product/000000003002009214/ EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3])====<br /> <br /> This report provides technical recommendations to resolve long-standing issues related to evaluation of multiple spurious operations and deterministic post-fire safe shutdown analyses. Note that the approaches and content from EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3 was incorporated into NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;4 and endorsed by the NRC in RG&amp;nbsp;1.189 Revision&amp;nbsp;4.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :*Clarified circuit failure modes and terminology including: proper polarity, latching versus non-latching, high impact components, failure mode classification and GFEHS<br /> :*Revised several PIRT panel positions following the conclusions of the PRA Expert Panel<br /> :**Consideration of insulation type for the aggressor cable conductor is eliminated. This was eliminated due to the impracticality of tracking the conductor insulation for aggressor cables. As a result, the reported classifications are a function of the conductor insulation of the target conductor.<br /> :**Classification of inter-cable hot shorts for thermoset insulated conductors from &quot;implausible&quot; to &quot;plausible&quot; based on the PRA expert panel probabilities that did not support a classification of &quot;implausible&quot;<br /> :**Grouped single break ungrounded AC (from common CPT or distributed) with DC due to similarities in circuit failure type classification. <br /> :**Classified inter-cable hot shorts for double break design with TP insulated conductors as &quot;implausible&quot; for latching and &quot;incredible&quot; for non-latching circuits. This classification was deferred until the PRA Expert Panel completed their estimation. <br /> :*Developed technical design considerations for shorting switch applications<br /> :*Disposition of secondary fires due to a fire-induced open circuited current transformer<br /> :**Testing is documented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7228// NUREG/CR-7228, ''Open Secondary Testing of Window-Type Current Transformers'']<br /> <br /> ===Methodology for Modeling Plant Trip Probabilities in Nuclear Power Plant Fire Probabilistic Risk Assessment ([https://www.epri.com/#/pages/product/3002016053/ EPRI&amp;nbsp;3002016053])===<br /> Typically, a Fire PRA assumes a reactor trip for fire scenarios unless it can be demonstrated that no Fire PRA components are impacted and the reactor will not trip. As a result, very few Fire PRA scenarios are screened from quantification. The operating experience in the United States was reviewed and showed that only one in six events results in a plant trip, and the events are strongly correlated with a few ignition source bins mainly related to electrical distribution and the turbine generator. This report documents a methodology and screening process that can be applied to fire scenarios for ignition source bins where a plant trip is unlikely to occur. For qualifying scenarios, a 0.1 conditional trip probability can be applied.</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Cable_Selection_(Task_3)&diff=1196 Fire PRA Cable Selection (Task 3) 2021-11-12T13:46:37Z <p>User: /* Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure (EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3) */</p> <hr /> <div>==Task Overview==<br /> <br /> === Background ===<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. This document offers a more structured set of rules for selection of cables.<br /> <br /> === Purpose ===<br /> Conducting a Fire PRA in accordance with this procedure necessitates an analysis of fire-induced circuit failures beyond that typically conducted during original Fire PRAs. The circuit analysis elements of the project are conducted in three distinct phases: <br /> <br /> * Fire PRA cable selection (Task 3), <br /> * Detailed circuit failure analysis ([https://firepra.epri.com/index.php?title=Detailed_Circuit_Failure_Analysis_(Task_9) Task 9]), and<br /> * Circuit failure mode likelihood analysis ([https://firepra.epri.com/index.php?title=Circuit_Failure_Mode_Likelihood_Analysis_(Task_10) Task 10]).<br /> <br /> This task provides methods and instructions for conducting the first phase of circuit analysis–selecting Fire PRA cables (Task 3). The purpose of Task 3 is to identify for all Fire PRA components the circuits/cables associated with the components and the routing/plant location of the identified circuits/cables. These relationships can then be used to determine the Fire PRA components potentially affected by postulated fires at different plant locations. <br /> <br /> In most cases, it is advantageous to perform some or all of Task 9 (detailed circuit failure analysis) coincident with Task 3. The degree to which Task 3 and Task 9 are combined is highly dependent on numerous plant-specific factors. Considerations for combining the two tasks are incorporated in relevant sections of Chapter 3.<br /> <br /> === Scope ===<br /> Task 3 provides methods and technical considerations for identifying cables to be included in the Fire PRA Cable List. This task contains the following key elements: <br /> <br /> * Identify cables associated with Fire PRA equipment, <br /> * Determine plant routing and location for the Fire PRA cables,<br /> * Identify Fire PRA power supplies, and<br /> * Correlate Fire PRA cables to Fire PRA equipment and plant locations (fire compartments and/or fire areas). <br /> <br /> Implementation of plant-specific quality assurance and configuration control requirements that might apply to a Fire PRA is not within the scope of this task. Nor does this task address validating the accuracy of plant-specific data extracted from plant drawings, documents, or databases. Each plant should follow appropriate quality assurance, administrative, and configuration control procedures applicable to the work conducted. The need to validate input source documents should be addressed as part of assembling the prerequisite information.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Cable Selection and Location (CS)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix B, Appendix for Chapter 3, Example<br /> <br /> Appendix I, Appendix for Chapter 9, Examples of Components Circuits Analysis<br /> <br /> ==Supplemental Guidance==<br /> <br /> ===[https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01]===<br /> NEI&amp;nbsp;00&amp;#8209;01 documents the cable selection and circuit analysis processes as well as the criteria for deterministic analyses and Fire PRAs. <br /> * Parts of [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;2] are endorsed in NRC [https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML17340A875 RG&amp;#8209;1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;3] February&amp;nbsp;2018<br /> * [https://www.nrc.gov/docs/ML1935/ML19351D273.html NEI 00-01 Revision 4] was issued in December 2019 to include the topics addressed in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]. Parts of the NEI 00-01 revision, including the content from EPRI 3002009214 / NUREG/CR 7150 Volume 3, are endorsed in [https://www.nrc.gov/docs/ML2104/ML21048A441.pdf RG 1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;4] May 2021.<br /> <br /> ===Fire-Induced Spurious Operations===<br /> <br /> Additionally, since the publication of NUREG/CR-6850, significant research on fire-induced spurious operations has occurred. This has resulted in the publication of three EPRI/NRC reports on this subject. <br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Phenomena Identification and Ranking Table (PIRT) Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000000001026424/ EPRI&amp;nbsp;1026424 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;1])====<br /> This report documents a Phenomena Identification and Ranking Table (PIRT) exercise on fire-induced electrical circuit failures that may occur in nuclear power plants as a result of fire damage to cables. The results and conclusions of the PIRT panel are a primary input to the follow on PRA Expert Panel documented in Volume 2.<br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* The spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible.<br /> :* The spurious operation of DC compound-wound motor due to proper polarity hot shorts in the motive/power cabling is incredible.<br /> :* The ignition of a secondary fire from an open circuited CT secondary circuit with a turns ratio of 1200:5 or less is incredible (Note: This is later modified and clarified in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]).<br /> :* The guidance given in Nuclear Energy Institute, [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI 00-01, Rev. 2], Appendix B.1, can be applied safely to fire safe-shutdown methodologies throughout the plant in resolving concerns associated with Multiple High-Impedance Faults (MHIFs). (Note: Appendix B.1 of NEI 00-01, Rev. 2 offers a basis for concluding that MHIFs need not be considered provided there exists breaker coordination for any circuits damaged by the fire that should previously have been assessed for the effects of MHIFs and appropriate testing and maintenance is performed)<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Expert Elicitation Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000003002001989/ EPRI&amp;nbsp;3002001989 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;2])====<br /> This report documents the results of the PRA panel's expert elicitation that is used to develop the conditional probabilities of hot-short induced spurious operation &amp; duration of various control circuit configurations.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* A new failure mode, the Ground Fault Equivalent Hot Short (GFEHS) has been identified. A GFEHS occurs when fire damage results in conductors of the same or different cable developing a relatively low impedance fault with a ground plane. For the GFEHS to cause a hot short induced spurious operation, both a source and target conductor must short to the same ground plane and have a compatible power supply. Source conductors are those which can supply energy (voltage, current). Target conductors are associated with end devices such as a conductor connected to a solenoid or a conductor connected to a contactor of a motor starter.<br /> :** Spurious operation caused by shorting conductors through a surrogate ground path in ungrounded circuits as a result of fire induced damage, is a failure mode which occurred during the [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7100// DESIREE-Fire testing] and is referred to as “Ground Fault Equivalent Hot Short.” The probability of this failure mechanism with respect to cable-to-cable hot shorts is such that it warrants consideration for including in future testing programs and, subsequently, in analyzing post-fire safe-shutdown conditions.<br /> :*Conditional probabilities and spurious operation duration are covered in Task 10.<br /> <br /> :'''NRC Correspondence'''<br /> :* NRC Memo dated June 14, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1316/ML13165A209.pdf ML13165A209], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC letter to NEI, dated December 16, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1323/ML13238A280.pdf ML13238A280], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC Memo dated February 12, 2014, Supplemental Interim Technical Guidance on Fireinduced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1401/ML14017A091.pdf ML14017A091])<br /> :* NRC letter to NEI, dated April 23, 2014, Supplemental Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1408/ML14086A165.pdf ML14086A165])<br /> :(The memos and letters dated June 14, 2013, December 16, 2013, February 12, 2014, and April 23, 2014 referenced interim guidance until the issuance of NUREG/CR-7150, Volume 2, in May 2014. '''NUREG/CR-7150, Vol. 2 should be referred to as the official guidance. The purpose of the memos and letters is to trace NRC acceptance of the guidance.''')<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure ([https://www.epri.com/#/pages/product/000000003002009214/ EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3])====<br /> <br /> This report provides technical recommendations to resolve long-standing issues related to evaluation of multiple spurious operations and deterministic post-fire safe shutdown analyses. Note that the approaches and content from EPRI 3002009214 / NUREG/CR 7150 Volume 3 was incorporated into NEI 00-01 Revision 4 and endorsed by the NRC in RG 1.189 Revision 4.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :*Clarified circuit failure modes and terminology including: proper polarity, latching versus non-latching, high impact components, failure mode classification and GFEHS<br /> :*Revised several PIRT panel positions following the conclusions of the PRA Expert Panel<br /> :**Consideration of insulation type for the aggressor cable conductor is eliminated. This was eliminated due to the impracticality of tracking the conductor insulation for aggressor cables. As a result, the reported classifications are a function of the conductor insulation of the target conductor.<br /> :**Classification of inter-cable hot shorts for thermoset insulated conductors from &quot;implausible&quot; to &quot;plausible&quot; based on the PRA expert panel probabilities that did not support a classification of &quot;implausible&quot;<br /> :**Grouped single break ungrounded AC (from common CPT or distributed) with DC due to similarities in circuit failure type classification. <br /> :**Classified inter-cable hot shorts for double break design with TP insulated conductors as &quot;implausible&quot; for latching and &quot;incredible&quot; for non-latching circuits. This classification was deferred until the PRA Expert Panel completed their estimation. <br /> :*Developed technical design considerations for shorting switch applications<br /> :*Disposition of secondary fires due to a fire-induced open circuited current transformer<br /> :**Testing is documented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7228// NUREG/CR-7228, ''Open Secondary Testing of Window-Type Current Transformers'']<br /> <br /> ===Methodology for Modeling Plant Trip Probabilities in Nuclear Power Plant Fire Probabilistic Risk Assessment ([https://www.epri.com/#/pages/product/3002016053/ EPRI&amp;nbsp;3002016053])===<br /> Typically, a Fire PRA assumes a reactor trip for fire scenarios unless it can be demonstrated that no Fire PRA components are impacted and the reactor will not trip. As a result, very few Fire PRA scenarios are screened from quantification. The operating experience in the United States was reviewed and showed that only one in six events results in a plant trip, and the events are strongly correlated with a few ignition source bins mainly related to electrical distribution and the turbine generator. This report documents a methodology and screening process that can be applied to fire scenarios for ignition source bins where a plant trip is unlikely to occur. For qualifying scenarios, a 0.1 conditional trip probability can be applied.</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Cable_Selection_(Task_3)&diff=1195 Fire PRA Cable Selection (Task 3) 2021-11-12T13:45:46Z <p>User: /* NEI&amp;nbsp;00&amp;#8209;01 */</p> <hr /> <div>==Task Overview==<br /> <br /> === Background ===<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. This document offers a more structured set of rules for selection of cables.<br /> <br /> === Purpose ===<br /> Conducting a Fire PRA in accordance with this procedure necessitates an analysis of fire-induced circuit failures beyond that typically conducted during original Fire PRAs. The circuit analysis elements of the project are conducted in three distinct phases: <br /> <br /> * Fire PRA cable selection (Task 3), <br /> * Detailed circuit failure analysis ([https://firepra.epri.com/index.php?title=Detailed_Circuit_Failure_Analysis_(Task_9) Task 9]), and<br /> * Circuit failure mode likelihood analysis ([https://firepra.epri.com/index.php?title=Circuit_Failure_Mode_Likelihood_Analysis_(Task_10) Task 10]).<br /> <br /> This task provides methods and instructions for conducting the first phase of circuit analysis–selecting Fire PRA cables (Task 3). The purpose of Task 3 is to identify for all Fire PRA components the circuits/cables associated with the components and the routing/plant location of the identified circuits/cables. These relationships can then be used to determine the Fire PRA components potentially affected by postulated fires at different plant locations. <br /> <br /> In most cases, it is advantageous to perform some or all of Task 9 (detailed circuit failure analysis) coincident with Task 3. The degree to which Task 3 and Task 9 are combined is highly dependent on numerous plant-specific factors. Considerations for combining the two tasks are incorporated in relevant sections of Chapter 3.<br /> <br /> === Scope ===<br /> Task 3 provides methods and technical considerations for identifying cables to be included in the Fire PRA Cable List. This task contains the following key elements: <br /> <br /> * Identify cables associated with Fire PRA equipment, <br /> * Determine plant routing and location for the Fire PRA cables,<br /> * Identify Fire PRA power supplies, and<br /> * Correlate Fire PRA cables to Fire PRA equipment and plant locations (fire compartments and/or fire areas). <br /> <br /> Implementation of plant-specific quality assurance and configuration control requirements that might apply to a Fire PRA is not within the scope of this task. Nor does this task address validating the accuracy of plant-specific data extracted from plant drawings, documents, or databases. Each plant should follow appropriate quality assurance, administrative, and configuration control procedures applicable to the work conducted. The need to validate input source documents should be addressed as part of assembling the prerequisite information.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Cable Selection and Location (CS)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix B, Appendix for Chapter 3, Example<br /> <br /> Appendix I, Appendix for Chapter 9, Examples of Components Circuits Analysis<br /> <br /> ==Supplemental Guidance==<br /> <br /> ===[https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01]===<br /> NEI&amp;nbsp;00&amp;#8209;01 documents the cable selection and circuit analysis processes as well as the criteria for deterministic analyses and Fire PRAs. <br /> * Parts of [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;2] are endorsed in NRC [https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML17340A875 RG&amp;#8209;1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;3] February&amp;nbsp;2018<br /> * [https://www.nrc.gov/docs/ML1935/ML19351D273.html NEI 00-01 Revision 4] was issued in December 2019 to include the topics addressed in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]. Parts of the NEI 00-01 revision, including the content from EPRI 3002009214 / NUREG/CR 7150 Volume 3, are endorsed in [https://www.nrc.gov/docs/ML2104/ML21048A441.pdf RG 1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;4] May 2021.<br /> <br /> ===Fire-Induced Spurious Operations===<br /> <br /> Additionally, since the publication of NUREG/CR-6850, significant research on fire-induced spurious operations has occurred. This has resulted in the publication of three EPRI/NRC reports on this subject. <br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Phenomena Identification and Ranking Table (PIRT) Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000000001026424/ EPRI&amp;nbsp;1026424 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;1])====<br /> This report documents a Phenomena Identification and Ranking Table (PIRT) exercise on fire-induced electrical circuit failures that may occur in nuclear power plants as a result of fire damage to cables. The results and conclusions of the PIRT panel are a primary input to the follow on PRA Expert Panel documented in Volume 2.<br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* The spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible.<br /> :* The spurious operation of DC compound-wound motor due to proper polarity hot shorts in the motive/power cabling is incredible.<br /> :* The ignition of a secondary fire from an open circuited CT secondary circuit with a turns ratio of 1200:5 or less is incredible (Note: This is later modified and clarified in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]).<br /> :* The guidance given in Nuclear Energy Institute, [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI 00-01, Rev. 2], Appendix B.1, can be applied safely to fire safe-shutdown methodologies throughout the plant in resolving concerns associated with Multiple High-Impedance Faults (MHIFs). (Note: Appendix B.1 of NEI 00-01, Rev. 2 offers a basis for concluding that MHIFs need not be considered provided there exists breaker coordination for any circuits damaged by the fire that should previously have been assessed for the effects of MHIFs and appropriate testing and maintenance is performed)<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Expert Elicitation Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000003002001989/ EPRI&amp;nbsp;3002001989 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;2])====<br /> This report documents the results of the PRA panel's expert elicitation that is used to develop the conditional probabilities of hot-short induced spurious operation &amp; duration of various control circuit configurations.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* A new failure mode, the Ground Fault Equivalent Hot Short (GFEHS) has been identified. A GFEHS occurs when fire damage results in conductors of the same or different cable developing a relatively low impedance fault with a ground plane. For the GFEHS to cause a hot short induced spurious operation, both a source and target conductor must short to the same ground plane and have a compatible power supply. Source conductors are those which can supply energy (voltage, current). Target conductors are associated with end devices such as a conductor connected to a solenoid or a conductor connected to a contactor of a motor starter.<br /> :** Spurious operation caused by shorting conductors through a surrogate ground path in ungrounded circuits as a result of fire induced damage, is a failure mode which occurred during the [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7100// DESIREE-Fire testing] and is referred to as “Ground Fault Equivalent Hot Short.” The probability of this failure mechanism with respect to cable-to-cable hot shorts is such that it warrants consideration for including in future testing programs and, subsequently, in analyzing post-fire safe-shutdown conditions.<br /> :*Conditional probabilities and spurious operation duration are covered in Task 10.<br /> <br /> :'''NRC Correspondence'''<br /> :* NRC Memo dated June 14, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1316/ML13165A209.pdf ML13165A209], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC letter to NEI, dated December 16, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1323/ML13238A280.pdf ML13238A280], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC Memo dated February 12, 2014, Supplemental Interim Technical Guidance on Fireinduced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1401/ML14017A091.pdf ML14017A091])<br /> :* NRC letter to NEI, dated April 23, 2014, Supplemental Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1408/ML14086A165.pdf ML14086A165])<br /> :(The memos and letters dated June 14, 2013, December 16, 2013, February 12, 2014, and April 23, 2014 referenced interim guidance until the issuance of NUREG/CR-7150, Volume 2, in May 2014. '''NUREG/CR-7150, Vol. 2 should be referred to as the official guidance. The purpose of the memos and letters is to trace NRC acceptance of the guidance.''')<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure ([https://www.epri.com/#/pages/product/000000003002009214/ EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3])====<br /> <br /> This report provides technical recommendations to resolve long-standing issues related to evaluation of multiple spurious operations and deterministic post-fire safe shutdown analyses. <br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :*Clarified circuit failure modes and terminology including: proper polarity, latching versus non-latching, high impact components, failure mode classification and GFEHS<br /> :*Revised several PIRT panel positions following the conclusions of the PRA Expert Panel<br /> :**Consideration of insulation type for the aggressor cable conductor is eliminated. This was eliminated due to the impracticality of tracking the conductor insulation for aggressor cables. As a result, the reported classifications are a function of the conductor insulation of the target conductor.<br /> :**Classification of inter-cable hot shorts for thermoset insulated conductors from &quot;implausible&quot; to &quot;plausible&quot; based on the PRA expert panel probabilities that did not support a classification of &quot;implausible&quot;<br /> :**Grouped single break ungrounded AC (from common CPT or distributed) with DC due to similarities in circuit failure type classification. <br /> :**Classified inter-cable hot shorts for double break design with TP insulated conductors as &quot;implausible&quot; for latching and &quot;incredible&quot; for non-latching circuits. This classification was deferred until the PRA Expert Panel completed their estimation. <br /> :*Developed technical design considerations for shorting switch applications<br /> :*Disposition of secondary fires due to a fire-induced open circuited current transformer<br /> :**Testing is documented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7228// NUREG/CR-7228, ''Open Secondary Testing of Window-Type Current Transformers'']<br /> <br /> ===Methodology for Modeling Plant Trip Probabilities in Nuclear Power Plant Fire Probabilistic Risk Assessment ([https://www.epri.com/#/pages/product/3002016053/ EPRI&amp;nbsp;3002016053])===<br /> Typically, a Fire PRA assumes a reactor trip for fire scenarios unless it can be demonstrated that no Fire PRA components are impacted and the reactor will not trip. As a result, very few Fire PRA scenarios are screened from quantification. The operating experience in the United States was reviewed and showed that only one in six events results in a plant trip, and the events are strongly correlated with a few ignition source bins mainly related to electrical distribution and the turbine generator. This report documents a methodology and screening process that can be applied to fire scenarios for ignition source bins where a plant trip is unlikely to occur. For qualifying scenarios, a 0.1 conditional trip probability can be applied.</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Cable_Selection_(Task_3)&diff=1194 Fire PRA Cable Selection (Task 3) 2021-11-12T13:44:37Z <p>User: /* NEI&amp;nbsp;00&amp;#8209;01 */</p> <hr /> <div>==Task Overview==<br /> <br /> === Background ===<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. This document offers a more structured set of rules for selection of cables.<br /> <br /> === Purpose ===<br /> Conducting a Fire PRA in accordance with this procedure necessitates an analysis of fire-induced circuit failures beyond that typically conducted during original Fire PRAs. The circuit analysis elements of the project are conducted in three distinct phases: <br /> <br /> * Fire PRA cable selection (Task 3), <br /> * Detailed circuit failure analysis ([https://firepra.epri.com/index.php?title=Detailed_Circuit_Failure_Analysis_(Task_9) Task 9]), and<br /> * Circuit failure mode likelihood analysis ([https://firepra.epri.com/index.php?title=Circuit_Failure_Mode_Likelihood_Analysis_(Task_10) Task 10]).<br /> <br /> This task provides methods and instructions for conducting the first phase of circuit analysis–selecting Fire PRA cables (Task 3). The purpose of Task 3 is to identify for all Fire PRA components the circuits/cables associated with the components and the routing/plant location of the identified circuits/cables. These relationships can then be used to determine the Fire PRA components potentially affected by postulated fires at different plant locations. <br /> <br /> In most cases, it is advantageous to perform some or all of Task 9 (detailed circuit failure analysis) coincident with Task 3. The degree to which Task 3 and Task 9 are combined is highly dependent on numerous plant-specific factors. Considerations for combining the two tasks are incorporated in relevant sections of Chapter 3.<br /> <br /> === Scope ===<br /> Task 3 provides methods and technical considerations for identifying cables to be included in the Fire PRA Cable List. This task contains the following key elements: <br /> <br /> * Identify cables associated with Fire PRA equipment, <br /> * Determine plant routing and location for the Fire PRA cables,<br /> * Identify Fire PRA power supplies, and<br /> * Correlate Fire PRA cables to Fire PRA equipment and plant locations (fire compartments and/or fire areas). <br /> <br /> Implementation of plant-specific quality assurance and configuration control requirements that might apply to a Fire PRA is not within the scope of this task. Nor does this task address validating the accuracy of plant-specific data extracted from plant drawings, documents, or databases. Each plant should follow appropriate quality assurance, administrative, and configuration control procedures applicable to the work conducted. The need to validate input source documents should be addressed as part of assembling the prerequisite information.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Cable Selection and Location (CS)<br /> <br /> ==Related EPRI 1011989 NUREG/CR-6850 Appendices==<br /> Appendix B, Appendix for Chapter 3, Example<br /> <br /> Appendix I, Appendix for Chapter 9, Examples of Components Circuits Analysis<br /> <br /> ==Supplemental Guidance==<br /> <br /> ===[https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01]===<br /> NEI&amp;nbsp;00&amp;#8209;01 documents the cable selection and circuit analysis processes as well as the criteria for deterministic analyses and Fire PRAs. <br /> * Parts of [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI&amp;nbsp;00&amp;#8209;01 Revision&amp;nbsp;2] are endorsed in NRC [https://adamswebsearch2.nrc.gov/webSearch2/main.jsp?AccessionNumber=ML17340A875 RG&amp;#8209;1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;3] February&amp;nbsp;2018<br /> * [https://www.nrc.gov/docs/ML1935/ML19351D273.html NEI 00-01 Revision 4] was issued in December 2019 to include the topics addressed in EPRI 3002009214 / NUREG/CR 7150 Volume 3. Parts of the NEI 00-01 revision, including the content from EPRI 3002009214 / NUREG/CR 7150 Volume 3, are endorsed in [https://www.nrc.gov/docs/ML2104/ML21048A441.pdf RG 1.189, ''Fire Protection for Nuclear Power Plants'' Revision&amp;nbsp;4] May 2021.<br /> <br /> ===Fire-Induced Spurious Operations===<br /> <br /> Additionally, since the publication of NUREG/CR-6850, significant research on fire-induced spurious operations has occurred. This has resulted in the publication of three EPRI/NRC reports on this subject. <br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Phenomena Identification and Ranking Table (PIRT) Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000000001026424/ EPRI&amp;nbsp;1026424 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;1])====<br /> This report documents a Phenomena Identification and Ranking Table (PIRT) exercise on fire-induced electrical circuit failures that may occur in nuclear power plants as a result of fire damage to cables. The results and conclusions of the PIRT panel are a primary input to the follow on PRA Expert Panel documented in Volume 2.<br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* The spurious operation of a three-phase AC motor due to proper polarity hot shorts on three-phase power cabling is incredible.<br /> :* The spurious operation of DC compound-wound motor due to proper polarity hot shorts in the motive/power cabling is incredible.<br /> :* The ignition of a secondary fire from an open circuited CT secondary circuit with a turns ratio of 1200:5 or less is incredible (Note: This is later modified and clarified in [https://www.epri.com/#/pages/product/000000003002009214/ EPRI 3002009214 / NUREG/CR-7150 Volume 3]).<br /> :* The guidance given in Nuclear Energy Institute, [https://www.nrc.gov/docs/ML0917/ML091770265.pdf NEI 00-01, Rev. 2], Appendix B.1, can be applied safely to fire safe-shutdown methodologies throughout the plant in resolving concerns associated with Multiple High-Impedance Faults (MHIFs). (Note: Appendix B.1 of NEI 00-01, Rev. 2 offers a basis for concluding that MHIFs need not be considered provided there exists breaker coordination for any circuits damaged by the fire that should previously have been assessed for the effects of MHIFs and appropriate testing and maintenance is performed)<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Expert Elicitation Exercise for Nuclear Power Plant Fire-Induced Electrical Circuit Failure ([https://www.epri.com/#/pages/product/000000003002001989/ EPRI&amp;nbsp;3002001989 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;2])====<br /> This report documents the results of the PRA panel's expert elicitation that is used to develop the conditional probabilities of hot-short induced spurious operation &amp; duration of various control circuit configurations.<br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :* A new failure mode, the Ground Fault Equivalent Hot Short (GFEHS) has been identified. A GFEHS occurs when fire damage results in conductors of the same or different cable developing a relatively low impedance fault with a ground plane. For the GFEHS to cause a hot short induced spurious operation, both a source and target conductor must short to the same ground plane and have a compatible power supply. Source conductors are those which can supply energy (voltage, current). Target conductors are associated with end devices such as a conductor connected to a solenoid or a conductor connected to a contactor of a motor starter.<br /> :** Spurious operation caused by shorting conductors through a surrogate ground path in ungrounded circuits as a result of fire induced damage, is a failure mode which occurred during the [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7100// DESIREE-Fire testing] and is referred to as “Ground Fault Equivalent Hot Short.” The probability of this failure mechanism with respect to cable-to-cable hot shorts is such that it warrants consideration for including in future testing programs and, subsequently, in analyzing post-fire safe-shutdown conditions.<br /> :*Conditional probabilities and spurious operation duration are covered in Task 10.<br /> <br /> :'''NRC Correspondence'''<br /> :* NRC Memo dated June 14, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1316/ML13165A209.pdf ML13165A209], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC letter to NEI, dated December 16, 2013, Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis and Enclosure (ADAMS Accession Nos. [https://www.nrc.gov/docs/ML1323/ML13238A280.pdf ML13238A280], [https://www.nrc.gov/docs/ML1316/ML13165A214.pdf ML13165A214])<br /> :* NRC Memo dated February 12, 2014, Supplemental Interim Technical Guidance on Fireinduced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1401/ML14017A091.pdf ML14017A091])<br /> :* NRC letter to NEI, dated April 23, 2014, Supplemental Interim Technical Guidance on Fire-Induced Circuit Failure Mode Likelihood Analysis (ADAMS Accession No. [https://www.nrc.gov/docs/ML1408/ML14086A165.pdf ML14086A165])<br /> :(The memos and letters dated June 14, 2013, December 16, 2013, February 12, 2014, and April 23, 2014 referenced interim guidance until the issuance of NUREG/CR-7150, Volume 2, in May 2014. '''NUREG/CR-7150, Vol. 2 should be referred to as the official guidance. The purpose of the memos and letters is to trace NRC acceptance of the guidance.''')<br /> <br /> ====Joint Assessment of Cable Damage and Quantification of Effects from Fire (JACQUE-FIRE): Technical Resolution to Open Issues on Nuclear Power Plant Fire-Induced Circuit Failure ([https://www.epri.com/#/pages/product/000000003002009214/ EPRI&amp;nbsp;3002009214 / NUREG/CR&amp;#8209;7150 Volume&amp;nbsp;3])====<br /> <br /> This report provides technical recommendations to resolve long-standing issues related to evaluation of multiple spurious operations and deterministic post-fire safe shutdown analyses. <br /> <br /> :'''Impact on EPRI 1011989 NUREG/CR-6850 Guidance'''<br /> :*Clarified circuit failure modes and terminology including: proper polarity, latching versus non-latching, high impact components, failure mode classification and GFEHS<br /> :*Revised several PIRT panel positions following the conclusions of the PRA Expert Panel<br /> :**Consideration of insulation type for the aggressor cable conductor is eliminated. This was eliminated due to the impracticality of tracking the conductor insulation for aggressor cables. As a result, the reported classifications are a function of the conductor insulation of the target conductor.<br /> :**Classification of inter-cable hot shorts for thermoset insulated conductors from &quot;implausible&quot; to &quot;plausible&quot; based on the PRA expert panel probabilities that did not support a classification of &quot;implausible&quot;<br /> :**Grouped single break ungrounded AC (from common CPT or distributed) with DC due to similarities in circuit failure type classification. <br /> :**Classified inter-cable hot shorts for double break design with TP insulated conductors as &quot;implausible&quot; for latching and &quot;incredible&quot; for non-latching circuits. This classification was deferred until the PRA Expert Panel completed their estimation. <br /> :*Developed technical design considerations for shorting switch applications<br /> :*Disposition of secondary fires due to a fire-induced open circuited current transformer<br /> :**Testing is documented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7228// NUREG/CR-7228, ''Open Secondary Testing of Window-Type Current Transformers'']<br /> <br /> ===Methodology for Modeling Plant Trip Probabilities in Nuclear Power Plant Fire Probabilistic Risk Assessment ([https://www.epri.com/#/pages/product/3002016053/ EPRI&amp;nbsp;3002016053])===<br /> Typically, a Fire PRA assumes a reactor trip for fire scenarios unless it can be demonstrated that no Fire PRA components are impacted and the reactor will not trip. As a result, very few Fire PRA scenarios are screened from quantification. The operating experience in the United States was reviewed and showed that only one in six events results in a plant trip, and the events are strongly correlated with a few ignition source bins mainly related to electrical distribution and the turbine generator. This report documents a methodology and screening process that can be applied to fire scenarios for ignition source bins where a plant trip is unlikely to occur. For qualifying scenarios, a 0.1 conditional trip probability can be applied.</div> User https://firepra.epri.com/index.php?title=Technology_Transfer&diff=1193 Technology Transfer 2021-11-10T16:33:37Z <p>User: </p> <hr /> <div>EPRI and NRC-RES periodically publish the material from the jointly held EPRI/NRC-RES Fire PRA Training. This annual training covers the main technical topics of developing a fire PRA. <br /> <br /> In 2021, EPRI/NRC training covered Fire Analysis and Electrical Analysis in an online virtual format. Training materials (slides) and recordings are available at the following Box locations:<br /> *[https://epri.box.com/s/fomlf3oxttabylxurvp4zjgb0yim8jx6 Fire Analysis]<br /> *[https://epri.box.com/s/mmvbtwrn1rc9jeg438lbup1it0xt1v41 Electrical Analysis]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005206/?lang=en-US EPRI 3002005206 / NUREG/CP-0307] documents the slides presented in the 2016 EPRI/NRC Fire PRA Training Course. The five modules covered in this report include:<br /> *Fire PRA<br /> *Electrical Analysis<br /> *Fire Analysis<br /> *Fire Human Reliability Analysis (HRA)<br /> *Advanced Fire Modeling <br /> <br /> [https://www.epri.com/#/pages/product/000000003002005205/?lang=en-US EPRI 3002005205 / NUREG/CP-0303] documents both sessions of the 2012 EPRI/NRC-RES Fire PRA Training. This report includes the slides and handouts in each module as well as video recordings of the training. The slides from the training are accessible via the links below. To obtain the recordings please contact the EPRI Order Center at 1-800-313-3774 Option 2 or 650-855-2121. You may also send an email to orders@epri.com or EPRI members can log in and use the Order Request Form.<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v1/ Fire PRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v2/ Electrical Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v3/ Fire Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v4/ Fire HRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v5/ Advanced Fire Modeling]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002000267/?lang=en-US EPRI 3002000267 / NUREG/CP-0301] documents the course prerequisites and Fire HRA course from the 2010 EPRI/NRC-RES Fire PRA Training. Similar to EPRI 3002005205, the slides can be viewed via the links below, but the recordings of the training must be ordered. <br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v1/ Volume 1] covers the basic concepts of circuit analysis, fire analysis, fire HRA, and PRA<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v2/ Volume 2] covers the initial offering of the Fire HRA course.</div> User https://firepra.epri.com/index.php?title=Technology_Transfer&diff=1192 Technology Transfer 2021-11-10T16:33:22Z <p>User: </p> <hr /> <div>EPRI and NRC-RES periodically publish the material from the jointly held EPRI/NRC-RES Fire PRA Training. This annual training covers the main technical topics of developing a fire PRA. <br /> <br /> In 2021, EPRI/NRC training covered Fire Analysis and Electrical Analysis in an online virtual format. Training materials (slides) and recordings are aviailable at the following Box locations:<br /> *[https://epri.box.com/s/fomlf3oxttabylxurvp4zjgb0yim8jx6 Fire Analysis]<br /> *[https://epri.box.com/s/mmvbtwrn1rc9jeg438lbup1it0xt1v41 Electrical Analysis]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005206/?lang=en-US EPRI 3002005206 / NUREG/CP-0307] documents the slides presented in the 2016 EPRI/NRC Fire PRA Training Course. The five modules covered in this report include:<br /> *Fire PRA<br /> *Electrical Analysis<br /> *Fire Analysis<br /> *Fire Human Reliability Analysis (HRA)<br /> *Advanced Fire Modeling <br /> <br /> [https://www.epri.com/#/pages/product/000000003002005205/?lang=en-US EPRI 3002005205 / NUREG/CP-0303] documents both sessions of the 2012 EPRI/NRC-RES Fire PRA Training. This report includes the slides and handouts in each module as well as video recordings of the training. The slides from the training are accessible via the links below. To obtain the recordings please contact the EPRI Order Center at 1-800-313-3774 Option 2 or 650-855-2121. You may also send an email to orders@epri.com or EPRI members can log in and use the Order Request Form.<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v1/ Fire PRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v2/ Electrical Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v3/ Fire Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v4/ Fire HRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v5/ Advanced Fire Modeling]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002000267/?lang=en-US EPRI 3002000267 / NUREG/CP-0301] documents the course prerequisites and Fire HRA course from the 2010 EPRI/NRC-RES Fire PRA Training. Similar to EPRI 3002005205, the slides can be viewed via the links below, but the recordings of the training must be ordered. <br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v1/ Volume 1] covers the basic concepts of circuit analysis, fire analysis, fire HRA, and PRA<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v2/ Volume 2] covers the initial offering of the Fire HRA course.</div> User https://firepra.epri.com/index.php?title=Technology_Transfer&diff=1191 Technology Transfer 2021-11-10T16:32:54Z <p>User: </p> <hr /> <div>EPRI and NRC-RES periodically publish the material from the jointly held EPRI/NRC-RES Fire PRA Training. This annual training covers the main technical topics of developing a fire PRA. <br /> <br /> In 2021, EPRI/NRC training covered Fire Analysis and Electrical Analysis. Training materials (slides) and recordings are aviailable at the following Box locations:<br /> *[https://epri.box.com/s/fomlf3oxttabylxurvp4zjgb0yim8jx6 Fire Analysis]<br /> *[https://epri.box.com/s/mmvbtwrn1rc9jeg438lbup1it0xt1v41 Electrical Analysis]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005206/?lang=en-US EPRI 3002005206 / NUREG/CP-0307] documents the slides presented in the 2016 EPRI/NRC Fire PRA Training Course. The five modules covered in this report include:<br /> *Fire PRA<br /> *Electrical Analysis<br /> *Fire Analysis<br /> *Fire Human Reliability Analysis (HRA)<br /> *Advanced Fire Modeling <br /> <br /> [https://www.epri.com/#/pages/product/000000003002005205/?lang=en-US EPRI 3002005205 / NUREG/CP-0303] documents both sessions of the 2012 EPRI/NRC-RES Fire PRA Training. This report includes the slides and handouts in each module as well as video recordings of the training. The slides from the training are accessible via the links below. To obtain the recordings please contact the EPRI Order Center at 1-800-313-3774 Option 2 or 650-855-2121. You may also send an email to orders@epri.com or EPRI members can log in and use the Order Request Form.<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v1/ Fire PRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v2/ Electrical Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v3/ Fire Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v4/ Fire HRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v5/ Advanced Fire Modeling]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002000267/?lang=en-US EPRI 3002000267 / NUREG/CP-0301] documents the course prerequisites and Fire HRA course from the 2010 EPRI/NRC-RES Fire PRA Training. Similar to EPRI 3002005205, the slides can be viewed via the links below, but the recordings of the training must be ordered. <br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v1/ Volume 1] covers the basic concepts of circuit analysis, fire analysis, fire HRA, and PRA<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v2/ Volume 2] covers the initial offering of the Fire HRA course.</div> User https://firepra.epri.com/index.php?title=Technology_Transfer&diff=1190 Technology Transfer 2021-11-10T16:31:32Z <p>User: </p> <hr /> <div>EPRI and NRC-RES periodically publish the material from the jointly held EPRI/NRC-RES Fire PRA Training. This annual training covers the main technical topics of developing a fire PRA. <br /> <br /> In 2021, EPRI/NRC training covered Fire Analysis and Electrical Analysis:<br /> *[https://epri.box.com/s/fomlf3oxttabylxurvp4zjgb0yim8jx6 Fire Analysis]<br /> *[https://epri.box.com/s/mmvbtwrn1rc9jeg438lbup1it0xt1v41 Electrical Analysis]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005206/?lang=en-US EPRI 3002005206 / NUREG/CP-0307] documents the slides presented in the 2016 EPRI/NRC Fire PRA Training Course. The five modules covered in this report include:<br /> *Fire PRA<br /> *Electrical Analysis<br /> *Fire Analysis<br /> *Fire Human Reliability Analysis (HRA)<br /> *Advanced Fire Modeling <br /> <br /> [https://www.epri.com/#/pages/product/000000003002005205/?lang=en-US EPRI 3002005205 / NUREG/CP-0303] documents both sessions of the 2012 EPRI/NRC-RES Fire PRA Training. This report includes the slides and handouts in each module as well as video recordings of the training. The slides from the training are accessible via the links below. To obtain the recordings please contact the EPRI Order Center at 1-800-313-3774 Option 2 or 650-855-2121. You may also send an email to orders@epri.com or EPRI members can log in and use the Order Request Form.<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v1/ Fire PRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v2/ Electrical Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v3/ Fire Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v4/ Fire HRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v5/ Advanced Fire Modeling]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002000267/?lang=en-US EPRI 3002000267 / NUREG/CP-0301] documents the course prerequisites and Fire HRA course from the 2010 EPRI/NRC-RES Fire PRA Training. Similar to EPRI 3002005205, the slides can be viewed via the links below, but the recordings of the training must be ordered. <br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v1/ Volume 1] covers the basic concepts of circuit analysis, fire analysis, fire HRA, and PRA<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v2/ Volume 2] covers the initial offering of the Fire HRA course.</div> User https://firepra.epri.com/index.php?title=Technology_Transfer&diff=1189 Technology Transfer 2021-11-10T16:30:41Z <p>User: </p> <hr /> <div>EPRI and NRC-RES periodically publish the material from the jointly held EPRI/NRC-RES Fire PRA Training. This annual training covers the main technical topics of developing a fire PRA. <br /> <br /> In 2021, EPRI / NRC training covered Fire Analysis and Electrical Analysis:<br /> *[https://epri.box.com/s/fomlf3oxttabylxurvp4zjgb0yim8jx6 Fire Analysis]<br /> *[https://epri.box.com/s/mmvbtwrn1rc9jeg438lbup1it0xt1v41 Electrical Analysis]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005206/?lang=en-US EPRI 3002005206 / NUREG/CP-0307] documents the slides presented in the 2016 EPRI/NRC Fire PRA Training Course. The five modules covered in this report include:<br /> *Fire PRA<br /> *Electrical Analysis<br /> *Fire Analysis<br /> *Fire Human Reliability Analysis (HRA)<br /> *Advanced Fire Modeling <br /> <br /> [https://www.epri.com/#/pages/product/000000003002005205/?lang=en-US EPRI 3002005205 / NUREG/CP-0303] documents both sessions of the 2012 EPRI/NRC-RES Fire PRA Training. This report includes the slides and handouts in each module as well as video recordings of the training. The slides from the training are accessible via the links below. To obtain the recordings please contact the EPRI Order Center at 1-800-313-3774 Option 2 or 650-855-2121. You may also send an email to orders@epri.com or EPRI members can log in and use the Order Request Form.<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v1/ Fire PRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v2/ Electrical Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v3/ Fire Analysis]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v4/ Fire HRA]<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0303/v5/ Advanced Fire Modeling]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002000267/?lang=en-US EPRI 3002000267 / NUREG/CP-0301] documents the course prerequisites and Fire HRA course from the 2010 EPRI/NRC-RES Fire PRA Training. Similar to EPRI 3002005205, the slides can be viewed via the links below, but the recordings of the training must be ordered. <br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v1/ Volume 1] covers the basic concepts of circuit analysis, fire analysis, fire HRA, and PRA<br /> *[https://www.nrc.gov/reading-rm/doc-collections/nuregs/conference/cp0301/v2/ Volume 2] covers the initial offering of the Fire HRA course.</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1188 Detailed Fire Modeling (Task 11) 2021-11-10T15:51:58Z <p>User: /* Fire Models Included in V&amp;V Guidance */</p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> EPRI FIVE<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 11<br /> | style=&quot;text-align: center;&quot; | 385<br /> | style=&quot;text-align: center;&quot; | 0.029<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | &lt;div id=&quot;028&quot;&gt;&lt;/div&gt;0.028[[#028Note|&lt;sup&gt;^&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 0.044<br /> | [https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ&amp;nbsp;17&amp;#8209;0013]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> &lt;div id=&quot;028Note&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#028|^]] ''[https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ 17-0013] reported the 50th percentile as 0.029. When calculated using the chi-squared distribution the calculated 50th percentile 0.028 as shown in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230].''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Methodology&diff=1187 Fire PRA Methodology 2021-07-16T20:42:41Z <p>User: </p> <hr /> <div>__NOTOC__<br /> This wiki is intended to serve the needs of a fire risk analysis team by describing a structured framework for conduct of the overall analysis, as well as providing references to specific recommended practices to address each key aspect of the analysis. This information follows the layout of [https://www.epri.com/#/pages/product/000000000001011989/ EPRI 1011989 / NUREG/CR-6850]. The methodology described here addresses the processes for the performance of a Fire PRA that focuses on a Level 1 PRA (core damage frequency - CDF) with consideration of large early release frequency (LERF). The wiki pages for each fire PRA task describe the task overview (including objective, purpose, and scope), related element of the ASME/ANS PRA Standard, related appendices in EPRI 1011989 / NUREG/CR-6850, and any supplemental guidance. The two most recent versions of the PRA Standard include ASME/ANS RA-Sa-2009 and ASME/ANS RA-Sb-2013. ASME/ANS RA-Sa-2009 was endorsed by the NRC in [https://www.nrc.gov/docs/ML0904/ML090410014.pdf RG 1.200 Revision 2]. <br /> <br /> ==Fire PRA Process Overview==<br /> &lt;imagemap&gt;<br /> File:FireScenarioAnalysis.png|950px|Figure 2-1. Overview of the Fire PRA Process<br /> <br /> rect 901 50 1392 170 [[#Plant Boundary Definition and Partitioning (Task 1)]]<br /> rect 900 270 1391 405 [[#Fire PRA Cable Selection (Task 3)]]<br /> rect 900 458 1391 575 [[#Qualitative Screening (Task 4)]]<br /> rect 900 624 1391 742 [[#Fire Ignition Frequency (Task 6)]]<br /> rect 1672 52 2161 168 [[#Fire PRA Component Selection (Task 2)]]<br /> rect 1698 455 2187 588 [[#Plant Fire-Induced Risk Model (Task 5)]]<br /> rect 900 812 1391 929 [[#Quantitative Screening (Task 7)]]<br /> rect 900 978 1391 1098 [[#Scoping Fire Modeling (Task 8)]]<br /> rect 901 1150 1392 1268 [[#Quantitative Screening (Task 7)]]<br /> rect 1698 812 2188 928 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 544 1548 1030 1665 [[#Detailed Circuit Failure Analysis (Task 9)]]<br /> rect 550 1724 1041 1875 [[#Circuit Failure Mode Likelihood Analysis (Task 10)]]<br /> rect 1270 1582 1762 1817 [[#Detailed Fire Modeling (Task 11)]]<br /> rect 152 2056 658 2170 [[#Seismic Fire Interactions (Task 13)]]<br /> rect 858 2056 1366 2180 [[#Fire Risk Quantification (Task 14)]]<br /> rect 1630 2055 2123 2178 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 858 2245 1366 2365 [[#Uncertainty and Sensitivity Analyses (Task 15)]]<br /> rect 860 2420 1366 2536 [[#Fire PRA Documentation (Task 16)]]<br /> <br /> <br /> desc bottom-left<br /> &lt;/imagemap&gt;<br /> <br /> The following considerations are important in the use of this figure.<br /> <br /> *A Fire PRA is iterative. Certain tasks may need refinement after conduct of one or more of the subsequent tasks. It may also be appropriate to incorporate only limited detail in the first pass through an analysis task, deferring the pursuit of additional detail pending the results of a later task. For example, the number of components and circuits credited in Tasks 2 and 3 is likely to be revised after attempts at screening in Tasks 4 and 7. The flow chart does not attempt to incorporate potential feedback loops. Analyst judgment is needed to ensure that an appropriate overall analysis process is followed consistent with study objectives.<br /> <br /> *Even though the process flow illustrated should work for predominant cases, users may find other analysis task sequences to be more appropriate for their objectives. Task sequence choices may, for example, be influenced by plant-specific fire protection features as well as the availability and depth of plant information supporting the Fire PRA. Each analysis task incorporates added detail into a given aspect of the Fire PRA. Task ordering is subject to practitioner judgment. Indeed, the task ordering applied to one set of fire scenarios may differ from that used in another set of scenarios within the same overall analysis.<br /> <br /> The following is a short description of each technical task for the overall Fire PRA methodology.<br /> <br /> ==Technical Tasks==<br /> <br /> ====[[Plant Boundary Definition and Partitioning (Task 1)]]====<br /> The first step in a Fire PRA is to define the physical boundary of the analysis, and to divide the area within that boundary into analysis compartments.<br /> <br /> ====[[Fire PRA Component Selection (Task 2)]]====<br /> The selection of components that are to be credited for plant shutdown following a fire is a critical step in any Fire PRA. Components selected would generally include any and all components credited in the 10 CFR 50 Appendix R post-fire SSD analysis. Additional components will likely be selected, potentially including any and all components credited in the plant’s internal events PRA. Also, the proposed methodology would likely introduce components beyond either the 10 CFR 50 Appendix R list or the internal events PRA model. Such components are often of interest due to considerations of combined spurious operations that may threaten the credited functions and components.<br /> <br /> ====[[Fire PRA Cable Selection (Task 3)]]====<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. EPRI 1011989 / NUREG/CR-6850 offers a more structured set of rules for selection of cables.<br /> <br /> ====[[Qualitative Screening (Task 4)]]====<br /> This task identifies fire analysis compartments that can be shown to have little or no risk significance without quantitative analysis. Fire compartments may be screened out if they contain no components or cables identified in Tasks 2 and 3, and if they cannot lead to a plant trip due to either plant procedures, an automatic trip signal, or technical specification requirements.<br /> <br /> ====[[Plant Fire-Induced Risk Model (Task 5)]]====<br /> This task discusses steps for the development of a logic model that reflects plant response following a fire. Specific instructions have been provided for treatment of fire-specific procedures or preplans. These procedures may impact availability of functions and components, or include fire-specific operator actions (e.g., self-induced-station-blackout).<br /> <br /> ====[[Fire Ignition Frequency (Task 6)]]====<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ====[[Quantitative Screening (Task 7)]]====<br /> A Fire PRA allows the screening of fire compartments and scenarios based on their contribution to fire risk. This approach considers the cumulative risk associated with the screened compartments (i.e., the ones not retained for detailed analysis) to ensure that a true estimate of fire risk profile (as opposed to vulnerability) is obtained. <br /> <br /> ====[[Scoping Fire Modeling (Task 8)]]====<br /> This step provides simple rules to define and screen fire ignition sources (and therefore fire scenarios) in an unscreened fire compartment.<br /> <br /> ====[[Detailed Circuit Failure Analysis (Task 9)]]====<br /> This task provides an approach and technical considerations for identifying how the failure of specific cables will impact the components included in the Fire PRA SSD plant response model.<br /> <br /> ====[[Circuit Failure Mode Likelihood Analysis (Task 10)]]====<br /> This task considers the relative likelihood of various circuit failure modes. This added level of resolution may be a desired option for those fire scenarios that are significant contributors to the risk. The methodology provided in this document benefits from the knowledge gained from the tests performed in response to the circuit failure issue.<br /> <br /> ====[[Detailed Fire Modeling (Task 11)]]====<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR-105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ====[[Post-Fire Human Reliability Analysis (Task 12)]]====<br /> This task considers operator actions for manipulation of plant components. The analysis task procedure provides structured instructions for identification and inclusion of these actions in the Fire PRA. The procedure also provides instructions for estimating screening human error probabilities (HEPs) before detailed fire modeling results (e.g., fire growth and damage behaviors) have been developed. Estimating HEP values with high confidence is critical to the effectiveness of screening in a Fire PRA. This report does not develop a detailed fire HRA methodology. There are a number of HRA methods that can be adopted for fire with appropriate additional instructions that superimpose fire effects on any of the existing HRA methods, such as SHARP, ATHEANA, etc. This would improve consistency across analyses i.e., fire and internal events PRA.<br /> <br /> ====[[Seismic Fire Interactions (Task 13)]]====<br /> This task is a qualitative approach to help identify the risk from any potential interactions between an earthquake and fire.<br /> <br /> ====[[Fire Risk Quantification (Task 14)]]====<br /> The task description provides recommendations for quantification and presentation of fire risk results.<br /> <br /> ====[[Uncertainty and Sensitivity Analyses (Task 15)]]====<br /> This task describes the approach to follow for identifying and treating uncertainties throughout the Fire PRA process. The treatment may vary from quantitative estimation and propagation of uncertainties where possible (e.g., in fire frequency and non-suppression probability) to identification of sources without quantitative estimation, where knowledge of a quantitative treatment of uncertainties is beyond the state-of-the-art. The treatment may also include one-at-a-time variation of individual parameter values to determine the effect on the overall fire risk (sensitivity analysis).<br /> <br /> ====[[Fire PRA Documentation (Task 16)]]====<br /> This provides suggestions for documenting a Fire PRA.<br /> <br /> ==Technology Transfer==<br /> Reports documenting past fire PRA trainings (including power point slides and video recordings of past trainings) are available [https://firepra.epri.com/index.php?title=Technology_Transfer here].</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Methodology&diff=1186 Fire PRA Methodology 2020-07-24T00:39:46Z <p>User: Adjusted coordinates.</p> <hr /> <div>__NOTOC__<br /> This wiki is intended to serve the needs of a fire risk analysis team by describing a structured framework for conduct of the overall analysis, as well as providing references to specific recommended practices to address each key aspect of the analysis. This information follows the layout of [https://www.epri.com/#/pages/product/000000000001011989/ EPRI 1011989 / NUREG/CR-6850]. The methodology described here addresses the processes for the performance of a Fire PRA that focuses on a Level 1 PRA (core damage frequency - CDF) with consideration of large early release frequency (LERF). The wiki pages for each fire PRA task describe the task overview (including objective, purpose, and scope), related element of the ASME/ANS PRA Standard, related appendices in EPRI 1011989 / NUREG/CR-6850, and any supplemental guidance. The two most recent versions of the PRA Standard include ASME/ANS RA-Sa-2009 and ASME/ANS RA-Sb-2013. ASME/ANS RA-Sa-2009 was endorsed by the NRC in [https://www.nrc.gov/docs/ML0904/ML090410014.pdf RG 1.200 Revision 2]. <br /> <br /> ==Fire PRA Process Overview==<br /> &lt;imagemap&gt;<br /> File:FireScenarioAnalysis.png|950px|Figure 2-1. Overview of the Fire PRA Process<br /> <br /> rect 901 50 1392 170 [[#Plant Boundary Definition and Partitioning (Task 1)]]<br /> rect 900 270 1391 405 [[#Fire PRA Cable Selection (Task 3)]]<br /> rect 900 458 1391 575 [[#Qualitative Screening (Task 4)]]<br /> rect 900 624 1391 742 [[#Fire Ignition Frequency (Task 6)]]<br /> rect 1672 52 2161 168 [[#Fire PRA Component Selection (Task 2)]]<br /> rect 1698 455 2187 588 [[#Plant Fire-Induced Risk Model (Task 5)]]<br /> rect 900 812 1391 929 [[#Quantitative Screening (Task 7)]]<br /> rect 900 978 1391 1098 [[#Scoping Fire Modeling (Task 8)]]<br /> rect 901 1150 1392 1268 [[#Quantitative Screening (Task 7)]]<br /> rect 1698 812 2188 928 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 544 1548 1030 1665 [[#Detailed Circuit Failure Analysis (Task 9)]]<br /> rect 550 1724 1041 1875 [[#Circuit Failure Mode Likelihood Analysis (Task 10)]]<br /> rect 1270 1582 1762 1817 [[#Detailed Fire Modeling (Task 11)]]<br /> rect 152 2056 658 2170 [[#Seismic Fire Interactions (Task 13)]]<br /> rect 858 2056 1366 2180 [[#Fire Risk Quantification (Task 14)]]<br /> rect 1630 2055 2123 2178 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 858 2245 1366 2365 [[#Uncertainty and Sensitivity Analyses (Task 15)]]<br /> rect 860 2420 1366 2536 [[#Fire PRA Documentation (Task 16)]]<br /> <br /> <br /> desc bottom-left<br /> &lt;/imagemap&gt;<br /> <br /> The following considerations are important in the use of this figure.<br /> <br /> *A Fire PRA is iterative. Certain tasks may need refinement after conduct of one or more of the subsequent tasks. It may also be appropriate to incorporate only limited detail in the first pass through an analysis task, deferring the pursuit of additional detail pending the results of a later task. For example, the number of components and circuits credited in Tasks 2 and 3 is likely to be revised after attempts at screening in Tasks 4 and 7. The flow chart does not attempt to incorporate potential feedback loops. Analyst judgment is needed to ensure that an appropriate overall analysis process is followed consistent with study objectives.<br /> <br /> *Even though the process flow illustrated should work for predominant cases, users may find other analysis task sequences to be more appropriate for their objectives. Task sequence choices may, for example, be influenced by plant-specific fire protection features as well as the availability and depth of plant information supporting the Fire PRA. Each analysis task incorporates added detail into a given aspect of the Fire PRA. Task ordering is subject to practitioner judgment. Indeed, the task ordering applied to one set of fire scenarios may differ from that used in another set of scenarios within the same overall analysis.<br /> <br /> The following is a short description of each technical task for the overall Fire PRA methodology.<br /> <br /> ==Technical Tasks==<br /> <br /> ====[[Plant Boundary Definition and Partitioning (Task 1)]]====<br /> The first step in a Fire PRA is to define the physical boundary of the analysis, and to divide the area within that boundary into analysis compartments.<br /> <br /> ====[[Fire PRA Component Selection (Task 2)]]====<br /> The selection of components that are to be credited for plant shutdown following a fire is a critical step in any Fire PRA. Components selected would generally include any and all components credited in the 10 CFR 50 Appendix R post-fire SSD analysis. Additional components will likely be selected, potentially including any and all components credited in the plant’s internal events PRA. Also, the proposed methodology would likely introduce components beyond either the 10 CFR 50 Appendix R list or the internal events PRA model. Such components are often of interest due to considerations of combined spurious operations that may threaten the credited functions and components.<br /> <br /> ====[[Fire PRA Cable Selection (Task 3)]]====<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. EPRI 1011989 / NUREG/CR-6850 offers a more structured set of rules for selection of cables.<br /> <br /> ====[[Qualitative Screening (Task 4)]]====<br /> This task identifies fire analysis compartments that can be shown to have little or no risk significance without quantitative analysis. Fire compartments may be screened out if they contain no components or cables identified in Tasks 2 and 3, and if they cannot lead to a plant trip due to either plant procedures, an automatic trip signal, or technical specification requirements.<br /> <br /> ====[[Plant Fire-Induced Risk Model (Task 5)]]====<br /> This task discusses steps for the development of a logic model that reflects plant response following a fire. Specific instructions have been provided for treatment of fire-specific procedures or preplans. These procedures may impact availability of functions and components, or include fire-specific operator actions (e.g., self-induced-station-blackout).<br /> <br /> ====[[Fire Ignition Frequency (Task 6)]]====<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ====[[Quantitative Screening (Task 7)]]====<br /> A Fire PRA allows the screening of fire compartments and scenarios based on their contribution to fire risk. This approach considers the cumulative risk associated with the screened compartments (i.e., the ones not retained for detailed analysis) to ensure that a true estimate of fire risk profile (as opposed to vulnerability) is obtained. <br /> <br /> ====[[Scoping Fire Modeling (Task 8)]]====<br /> This step provides simple rules to define and screen fire ignition sources (and therefore fire scenarios) in an unscreened fire compartment.<br /> <br /> ====[[Detailed Circuit Failure Analysis (Task 9)]]====<br /> This task provides an approach and technical considerations for identifying how the failure of specific cables will impact the components included in the Fire PRA SSD plant response model.<br /> <br /> ====[[Circuit Failure Mode Likelihood Analysis (Task 10)]]====<br /> This task considers the relative likelihood of various circuit failure modes. This added level of resolution may be a desired option for those fire scenarios that are significant contributors to the risk. The methodology provided in this document benefits from the knowledge gained from the tests performed in response to the circuit failure issue.<br /> <br /> ====[[Detailed Fire Modeling (Task 11)]]====<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR-105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ====[[Post-Fire Human Reliability Analysis (Task 12)]]====<br /> This task considers operator actions for manipulation of plant components. The analysis task procedure provides structured instructions for identification and inclusion of these actions in the Fire PRA. The procedure also provides instructions for estimating screening human error probabilities (HEPs) before detailed fire modeling results (e.g., fire growth and damage behaviors) have been developed. Estimating HEP values with high confidence is critical to the effectiveness of screening in a Fire PRA. This report does not develop a detailed fire HRA methodology. There are a number of HRA methods that can be adopted for fire with appropriate additional instructions that superimpose fire effects on any of the existing HRA methods, such as SHARP, ATHEANA, etc. This would improve consistency across analyses i.e., fire and internal events PRA.<br /> <br /> ====[[Seismic Fire Interactions (Task 13)]]====<br /> This task is a qualitative approach to help identify the risk from any potential interactions between an earthquake and fire.<br /> <br /> ====[[Fire Risk Quantification (Task 14)]]====<br /> The task description provides recommendations for quantification and presentation of fire risk results.<br /> <br /> ====[[Uncertainty and Sensitivity Analyses (Task 15)]]====<br /> This task describes the approach to follow for identifying and treating uncertainties throughout the Fire PRA process. The treatment may vary from quantitative estimation and propagation of uncertainties where possible (e.g., in fire frequency and non-suppression probability) to identification of sources without quantitative estimation, where knowledge of a quantitative treatment of uncertainties is beyond the state-of-the-art. The treatment may also include one-at-a-time variation of individual parameter values to determine the effect on the overall fire risk (sensitivity analysis).<br /> <br /> ====[[Fire PRA Documentation (Task 16)]]====<br /> This provides suggestions for documenting a Fire PRA.<br /> <br /> ==Technology Transfer==<br /> Reports documenting past fire PRA trainings (including power point slides and video recordings of past trainings) are available [https://firepra.epri.com/index.php?title=Technology_Transfer here].</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Methodology&diff=1185 Fire PRA Methodology 2020-07-24T00:38:18Z <p>User: Adjusted coordinates.</p> <hr /> <div>__NOTOC__<br /> This wiki is intended to serve the needs of a fire risk analysis team by describing a structured framework for conduct of the overall analysis, as well as providing references to specific recommended practices to address each key aspect of the analysis. This information follows the layout of [https://www.epri.com/#/pages/product/000000000001011989/ EPRI 1011989 / NUREG/CR-6850]. The methodology described here addresses the processes for the performance of a Fire PRA that focuses on a Level 1 PRA (core damage frequency - CDF) with consideration of large early release frequency (LERF). The wiki pages for each fire PRA task describe the task overview (including objective, purpose, and scope), related element of the ASME/ANS PRA Standard, related appendices in EPRI 1011989 / NUREG/CR-6850, and any supplemental guidance. The two most recent versions of the PRA Standard include ASME/ANS RA-Sa-2009 and ASME/ANS RA-Sb-2013. ASME/ANS RA-Sa-2009 was endorsed by the NRC in [https://www.nrc.gov/docs/ML0904/ML090410014.pdf RG 1.200 Revision 2]. <br /> <br /> ==Fire PRA Process Overview==<br /> &lt;imagemap&gt;<br /> File:FireScenarioAnalysis.png|950px|Figure 2-1. Overview of the Fire PRA Process<br /> <br /> rect 901 50 1392 170 [[#Plant Boundary Definition and Partitioning (Task 1)]]<br /> rect 900 270 1391 405 [[#Fire PRA Cable Selection (Task 3)]]<br /> rect 900 458 1391 575 [[#Qualitative Screening (Task 4)]]<br /> rect 900 624 1391 742 [[#Fire Ignition Frequency (Task 6)]]<br /> rect 1672 52 2161 168 [[#Fire PRA Component Selection (Task 2)]]<br /> rect 1698 455 2187 588 [[#Plant Fire-Induced Risk Model (Task 5)]]<br /> rect 900 812 1391 929 [[#Quantitative Screening (Task 7)]]<br /> rect 900 978 1391 1098 [[#Scoping Fire Modeling (Task 8)]]<br /> rect 901 1150 1392 1268 [[#Quantitative Screening (Task 7)]]<br /> rect 1698 812 2188 928 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 544 1548 1030 1665 [[#Detailed Circuit Failure Analysis (Task 9)]]<br /> rect 550 1724 1041 1875 [[#Circuit Failure Mode Likelihood Analysis (Task 10)]]<br /> rect 1270 1582 1762 1817 [[#Detailed Fire Modeling (Task 11)]]<br /> rect 152 2056 658 2170 [[#Seismic Fire Interactions (Task 13)]]<br /> rect 858 2056 1366 2180 [[#Fire Risk Quantification (Task 14)]]<br /> rect 1630 2055 2123 2178 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 858 2245 1366 2365 [[#Uncertainty and Sensitivity Analyses (Task 15)]]<br /> rect 860 2425 1366 2536 [[#Fire PRA Documentation (Task 16)]]<br /> <br /> <br /> desc bottom-left<br /> &lt;/imagemap&gt;<br /> <br /> The following considerations are important in the use of this figure.<br /> <br /> *A Fire PRA is iterative. Certain tasks may need refinement after conduct of one or more of the subsequent tasks. It may also be appropriate to incorporate only limited detail in the first pass through an analysis task, deferring the pursuit of additional detail pending the results of a later task. For example, the number of components and circuits credited in Tasks 2 and 3 is likely to be revised after attempts at screening in Tasks 4 and 7. The flow chart does not attempt to incorporate potential feedback loops. Analyst judgment is needed to ensure that an appropriate overall analysis process is followed consistent with study objectives.<br /> <br /> *Even though the process flow illustrated should work for predominant cases, users may find other analysis task sequences to be more appropriate for their objectives. Task sequence choices may, for example, be influenced by plant-specific fire protection features as well as the availability and depth of plant information supporting the Fire PRA. Each analysis task incorporates added detail into a given aspect of the Fire PRA. Task ordering is subject to practitioner judgment. Indeed, the task ordering applied to one set of fire scenarios may differ from that used in another set of scenarios within the same overall analysis.<br /> <br /> The following is a short description of each technical task for the overall Fire PRA methodology.<br /> <br /> ==Technical Tasks==<br /> <br /> ====[[Plant Boundary Definition and Partitioning (Task 1)]]====<br /> The first step in a Fire PRA is to define the physical boundary of the analysis, and to divide the area within that boundary into analysis compartments.<br /> <br /> ====[[Fire PRA Component Selection (Task 2)]]====<br /> The selection of components that are to be credited for plant shutdown following a fire is a critical step in any Fire PRA. Components selected would generally include any and all components credited in the 10 CFR 50 Appendix R post-fire SSD analysis. Additional components will likely be selected, potentially including any and all components credited in the plant’s internal events PRA. Also, the proposed methodology would likely introduce components beyond either the 10 CFR 50 Appendix R list or the internal events PRA model. Such components are often of interest due to considerations of combined spurious operations that may threaten the credited functions and components.<br /> <br /> ====[[Fire PRA Cable Selection (Task 3)]]====<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. EPRI 1011989 / NUREG/CR-6850 offers a more structured set of rules for selection of cables.<br /> <br /> ====[[Qualitative Screening (Task 4)]]====<br /> This task identifies fire analysis compartments that can be shown to have little or no risk significance without quantitative analysis. Fire compartments may be screened out if they contain no components or cables identified in Tasks 2 and 3, and if they cannot lead to a plant trip due to either plant procedures, an automatic trip signal, or technical specification requirements.<br /> <br /> ====[[Plant Fire-Induced Risk Model (Task 5)]]====<br /> This task discusses steps for the development of a logic model that reflects plant response following a fire. Specific instructions have been provided for treatment of fire-specific procedures or preplans. These procedures may impact availability of functions and components, or include fire-specific operator actions (e.g., self-induced-station-blackout).<br /> <br /> ====[[Fire Ignition Frequency (Task 6)]]====<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ====[[Quantitative Screening (Task 7)]]====<br /> A Fire PRA allows the screening of fire compartments and scenarios based on their contribution to fire risk. This approach considers the cumulative risk associated with the screened compartments (i.e., the ones not retained for detailed analysis) to ensure that a true estimate of fire risk profile (as opposed to vulnerability) is obtained. <br /> <br /> ====[[Scoping Fire Modeling (Task 8)]]====<br /> This step provides simple rules to define and screen fire ignition sources (and therefore fire scenarios) in an unscreened fire compartment.<br /> <br /> ====[[Detailed Circuit Failure Analysis (Task 9)]]====<br /> This task provides an approach and technical considerations for identifying how the failure of specific cables will impact the components included in the Fire PRA SSD plant response model.<br /> <br /> ====[[Circuit Failure Mode Likelihood Analysis (Task 10)]]====<br /> This task considers the relative likelihood of various circuit failure modes. This added level of resolution may be a desired option for those fire scenarios that are significant contributors to the risk. The methodology provided in this document benefits from the knowledge gained from the tests performed in response to the circuit failure issue.<br /> <br /> ====[[Detailed Fire Modeling (Task 11)]]====<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR-105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ====[[Post-Fire Human Reliability Analysis (Task 12)]]====<br /> This task considers operator actions for manipulation of plant components. The analysis task procedure provides structured instructions for identification and inclusion of these actions in the Fire PRA. The procedure also provides instructions for estimating screening human error probabilities (HEPs) before detailed fire modeling results (e.g., fire growth and damage behaviors) have been developed. Estimating HEP values with high confidence is critical to the effectiveness of screening in a Fire PRA. This report does not develop a detailed fire HRA methodology. There are a number of HRA methods that can be adopted for fire with appropriate additional instructions that superimpose fire effects on any of the existing HRA methods, such as SHARP, ATHEANA, etc. This would improve consistency across analyses i.e., fire and internal events PRA.<br /> <br /> ====[[Seismic Fire Interactions (Task 13)]]====<br /> This task is a qualitative approach to help identify the risk from any potential interactions between an earthquake and fire.<br /> <br /> ====[[Fire Risk Quantification (Task 14)]]====<br /> The task description provides recommendations for quantification and presentation of fire risk results.<br /> <br /> ====[[Uncertainty and Sensitivity Analyses (Task 15)]]====<br /> This task describes the approach to follow for identifying and treating uncertainties throughout the Fire PRA process. The treatment may vary from quantitative estimation and propagation of uncertainties where possible (e.g., in fire frequency and non-suppression probability) to identification of sources without quantitative estimation, where knowledge of a quantitative treatment of uncertainties is beyond the state-of-the-art. The treatment may also include one-at-a-time variation of individual parameter values to determine the effect on the overall fire risk (sensitivity analysis).<br /> <br /> ====[[Fire PRA Documentation (Task 16)]]====<br /> This provides suggestions for documenting a Fire PRA.<br /> <br /> ==Technology Transfer==<br /> Reports documenting past fire PRA trainings (including power point slides and video recordings of past trainings) are available [https://firepra.epri.com/index.php?title=Technology_Transfer here].</div> User https://firepra.epri.com/index.php?title=Fire_PRA_Methodology&diff=1184 Fire PRA Methodology 2020-07-24T00:02:16Z <p>User: </p> <hr /> <div>__NOTOC__<br /> This wiki is intended to serve the needs of a fire risk analysis team by describing a structured framework for conduct of the overall analysis, as well as providing references to specific recommended practices to address each key aspect of the analysis. This information follows the layout of [https://www.epri.com/#/pages/product/000000000001011989/ EPRI 1011989 / NUREG/CR-6850]. The methodology described here addresses the processes for the performance of a Fire PRA that focuses on a Level 1 PRA (core damage frequency - CDF) with consideration of large early release frequency (LERF). The wiki pages for each fire PRA task describe the task overview (including objective, purpose, and scope), related element of the ASME/ANS PRA Standard, related appendices in EPRI 1011989 / NUREG/CR-6850, and any supplemental guidance. The two most recent versions of the PRA Standard include ASME/ANS RA-Sa-2009 and ASME/ANS RA-Sb-2013. ASME/ANS RA-Sa-2009 was endorsed by the NRC in [https://www.nrc.gov/docs/ML0904/ML090410014.pdf RG 1.200 Revision 2]. <br /> <br /> ==Fire PRA Process Overview==<br /> &lt;imagemap&gt;<br /> File:FireScenarioAnalysis.png|950px|Figure 2-1. Overview of the Fire PRA Process<br /> <br /> rect 905 46 1382 155 [[#Plant Boundary Definition and Partitioning (Task 1)]]<br /> rect 903 266 1382 390 [[#Fire PRA Cable Selection (Task 3)]]<br /> rect 903 454 1382 565 [[#Qualitative Screening (Task 4)]]<br /> rect 903 618 1382 724 [[#Fire Ignition Frequency (Task 6)]]<br /> rect 1694 46 2176 155 [[#Fire PRA Component Selection (Task 2)]]<br /> rect 1694 449 2176 575 [[#Plant Fire-Induced Risk Model (Task 5)]]<br /> rect 903 805 1382 913 [[#Quantitative Screening (Task 7)]]<br /> rect 903 971 1382 1082 [[#Scoping Fire Modeling (Task 8)]]<br /> rect 903 1143 1382 1252 [[#Quantitative Screening (Task 7)]]<br /> rect 1694 804 2176 912 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 554 1538 1031 1647 [[#Detailed Circuit Failure Analysis (Task 9)]]<br /> rect 554 1711 1031 1856 [[#Circuit Failure Mode Likelihood Analysis (Task 10)]]<br /> rect 1270 1574 1752 1797 [[#Detailed Fire Modeling (Task 11)]]<br /> rect 156 2041 654 2150 [[#Seismic Fire Interactions (Task 13)]]<br /> rect 860 2040 1359 2157 [[#Fire Risk Quantification (Task 14)]]<br /> rect 1628 2040 2113 2157 [[#Post-Fire Human Reliability Analysis (Task 12)]]<br /> rect 860 2241 1359 2352 [[#Uncertainty and Sensitivity Analyses (Task 15)]]<br /> rect 860 2417 1359 2528 [[#Fire PRA Documentation (Task 16)]]<br /> <br /> <br /> desc bottom-left<br /> &lt;/imagemap&gt;<br /> <br /> The following considerations are important in the use of this figure.<br /> <br /> *A Fire PRA is iterative. Certain tasks may need refinement after conduct of one or more of the subsequent tasks. It may also be appropriate to incorporate only limited detail in the first pass through an analysis task, deferring the pursuit of additional detail pending the results of a later task. For example, the number of components and circuits credited in Tasks 2 and 3 is likely to be revised after attempts at screening in Tasks 4 and 7. The flow chart does not attempt to incorporate potential feedback loops. Analyst judgment is needed to ensure that an appropriate overall analysis process is followed consistent with study objectives.<br /> <br /> *Even though the process flow illustrated should work for predominant cases, users may find other analysis task sequences to be more appropriate for their objectives. Task sequence choices may, for example, be influenced by plant-specific fire protection features as well as the availability and depth of plant information supporting the Fire PRA. Each analysis task incorporates added detail into a given aspect of the Fire PRA. Task ordering is subject to practitioner judgment. Indeed, the task ordering applied to one set of fire scenarios may differ from that used in another set of scenarios within the same overall analysis.<br /> <br /> The following is a short description of each technical task for the overall Fire PRA methodology.<br /> <br /> ==Technical Tasks==<br /> <br /> ====[[Plant Boundary Definition and Partitioning (Task 1)]]====<br /> The first step in a Fire PRA is to define the physical boundary of the analysis, and to divide the area within that boundary into analysis compartments.<br /> <br /> ====[[Fire PRA Component Selection (Task 2)]]====<br /> The selection of components that are to be credited for plant shutdown following a fire is a critical step in any Fire PRA. Components selected would generally include any and all components credited in the 10 CFR 50 Appendix R post-fire SSD analysis. Additional components will likely be selected, potentially including any and all components credited in the plant’s internal events PRA. Also, the proposed methodology would likely introduce components beyond either the 10 CFR 50 Appendix R list or the internal events PRA model. Such components are often of interest due to considerations of combined spurious operations that may threaten the credited functions and components.<br /> <br /> ====[[Fire PRA Cable Selection (Task 3)]]====<br /> This task provides instructions and technical considerations associated with identifying cables supporting those components selected in Task 2. In previous Fire PRA methods (such as [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide [TR-105928, no longer available on epri.com]) this task was relegated to the SSD analysis and its associated databases. EPRI 1011989 / NUREG/CR-6850 offers a more structured set of rules for selection of cables.<br /> <br /> ====[[Qualitative Screening (Task 4)]]====<br /> This task identifies fire analysis compartments that can be shown to have little or no risk significance without quantitative analysis. Fire compartments may be screened out if they contain no components or cables identified in Tasks 2 and 3, and if they cannot lead to a plant trip due to either plant procedures, an automatic trip signal, or technical specification requirements.<br /> <br /> ====[[Plant Fire-Induced Risk Model (Task 5)]]====<br /> This task discusses steps for the development of a logic model that reflects plant response following a fire. Specific instructions have been provided for treatment of fire-specific procedures or preplans. These procedures may impact availability of functions and components, or include fire-specific operator actions (e.g., self-induced-station-blackout).<br /> <br /> ====[[Fire Ignition Frequency (Task 6)]]====<br /> This task describes the approach to develop frequency estimates for fire compartments and scenarios. Significant changes from the EPRI FIVE method have been made in this task. The changes generally relate to use of challenging events, considerations associated with data quality, and increased use of a fully component based ignition frequency model (as opposed to the location/component-based model used, for example, in FIVE).<br /> <br /> ====[[Quantitative Screening (Task 7)]]====<br /> A Fire PRA allows the screening of fire compartments and scenarios based on their contribution to fire risk. This approach considers the cumulative risk associated with the screened compartments (i.e., the ones not retained for detailed analysis) to ensure that a true estimate of fire risk profile (as opposed to vulnerability) is obtained. <br /> <br /> ====[[Scoping Fire Modeling (Task 8)]]====<br /> This step provides simple rules to define and screen fire ignition sources (and therefore fire scenarios) in an unscreened fire compartment.<br /> <br /> ====[[Detailed Circuit Failure Analysis (Task 9)]]====<br /> This task provides an approach and technical considerations for identifying how the failure of specific cables will impact the components included in the Fire PRA SSD plant response model.<br /> <br /> ====[[Circuit Failure Mode Likelihood Analysis (Task 10)]]====<br /> This task considers the relative likelihood of various circuit failure modes. This added level of resolution may be a desired option for those fire scenarios that are significant contributors to the risk. The methodology provided in this document benefits from the knowledge gained from the tests performed in response to the circuit failure issue.<br /> <br /> ====[[Detailed Fire Modeling (Task 11)]]====<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR-105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ====[[Post-Fire Human Reliability Analysis (Task 12)]]====<br /> This task considers operator actions for manipulation of plant components. The analysis task procedure provides structured instructions for identification and inclusion of these actions in the Fire PRA. The procedure also provides instructions for estimating screening human error probabilities (HEPs) before detailed fire modeling results (e.g., fire growth and damage behaviors) have been developed. Estimating HEP values with high confidence is critical to the effectiveness of screening in a Fire PRA. This report does not develop a detailed fire HRA methodology. There are a number of HRA methods that can be adopted for fire with appropriate additional instructions that superimpose fire effects on any of the existing HRA methods, such as SHARP, ATHEANA, etc. This would improve consistency across analyses i.e., fire and internal events PRA.<br /> <br /> ====[[Seismic Fire Interactions (Task 13)]]====<br /> This task is a qualitative approach to help identify the risk from any potential interactions between an earthquake and fire.<br /> <br /> ====[[Fire Risk Quantification (Task 14)]]====<br /> The task description provides recommendations for quantification and presentation of fire risk results.<br /> <br /> ====[[Uncertainty and Sensitivity Analyses (Task 15)]]====<br /> This task describes the approach to follow for identifying and treating uncertainties throughout the Fire PRA process. The treatment may vary from quantitative estimation and propagation of uncertainties where possible (e.g., in fire frequency and non-suppression probability) to identification of sources without quantitative estimation, where knowledge of a quantitative treatment of uncertainties is beyond the state-of-the-art. The treatment may also include one-at-a-time variation of individual parameter values to determine the effect on the overall fire risk (sensitivity analysis).<br /> <br /> ====[[Fire PRA Documentation (Task 16)]]====<br /> This provides suggestions for documenting a Fire PRA.<br /> <br /> ==Technology Transfer==<br /> Reports documenting past fire PRA trainings (including power point slides and video recordings of past trainings) are available [https://firepra.epri.com/index.php?title=Technology_Transfer here].</div> User https://firepra.epri.com/index.php?title=MediaWiki:Sidebar&diff=1183 MediaWiki:Sidebar 2020-07-21T23:12:54Z <p>User: </p> <hr /> <div><br /> * navigation<br /> ** Fire_PRA_Methodology|Fire PRA Methodology<br /> ** Plant_Boundary_Definition_and_Partitioning_(Task_1)|Plant Boundary Definition and Partitioning (Task 1)<br /> ** Fire_PRA_Component_Selection_(Task_2)|Fire PRA Component Selection (Task 2)<br /> ** Fire_PRA_Cable_Selection_(Task 3)|Fire PRA Cable Selection (Task 3)<br /> ** Qualitative Screening (Task 4)|Qualitative Screening (Task 4)<br /> ** Plant_Fire-Induced_Risk_Model_(Task_5)|Plant Fire-Induced Risk Model (Task 5)<br /> ** Fire_Ignition_Frequency_(Task_6)|Fire Ignition Frequency (Task 6)<br /> ** Quantitative_Screening_(Task_7)|Quantitative Screening (Task 7)<br /> ** Scoping_Fire_Modeling_(Task_8)|Scoping Fire Modeling (Task 8)<br /> ** Detailed_Circuit_Failure_Analysis_(Task_9)|Detailed Circuit Failure Analysis (Task 9)<br /> ** Circuit_Failure_Mode_Likelihood_Analysis_(Task_10)|Circuit Failure Mode Likelihood Analysis (Task 10)<br /> ** Detailed_Fire_Modeling_(Task_11)|Detailed Fire Modeling (Task 11)<br /> ** Post-Fire_Human_Reliability_Analysis_(Task_12)|Post-Fire Human Reliability Analysis (Task 12)<br /> ** Seismic_Fire_Interactions_(Task_13)|Seismic Fire Interactions (Task 13)<br /> ** Fire_Risk_Quantification_(Task_14)|Fire Risk Quantification (Task 14)<br /> ** Uncertainty_and_Sensitivity_Analyses_(Task_15)|Uncertainty and Sensitivity Analyses (Task 15)<br /> ** Fire_PRA_Documentation_(Task_16)|Fire PRA Documentation (Task 16)<br /> ** Technology_Transfer|Technology Transfer<br /> * Feedback<br /> ** mailto:crochon@epri.com|Send Feedback</div> User https://firepra.epri.com/index.php?title=MediaWiki:Common.css&diff=1182 MediaWiki:Common.css 2020-07-20T21:53:54Z <p>User: </p> <hr /> <div>/* CSS placed here will be applied to all skins */<br /> <br /> #pt-login, #p-tb, #ca-history, #ca-viewsource, #ca-talk{<br /> display:none!important;<br /> }<br /> <br /> /* CSS placed here will be applied to all skins */<br /> #pt-logout a{<br /> content: &quot;&quot;;<br /> visibility: hidden;<br /> }<br /> <br /> #pt-logout a:before{<br /> content: &quot;Admin Logout&quot;;<br /> visibility: visible;<br /> }<br /> <br /> #pt-login a{<br /> content: &quot;&quot;;<br /> visibility: hidden;<br /> }<br /> <br /> #pt-login a:before{<br /> content: &quot;Administration&quot;;<br /> visibility: visible;<br /> }</div> User https://firepra.epri.com/index.php?title=MediaWiki:Sidebar&diff=1181 MediaWiki:Sidebar 2020-07-20T21:51:56Z <p>User: </p> <hr /> <div><br /> * navigation<br /> ** Fire_PRA_Methodology|Fire PRA Methodology<br /> ** Plant_Boundary_Definition_and_Partitioning_(Task_1)|Plant Boundary Definition and Partitioning (Task 1)<br /> ** Fire_PRA_Component_Selection_(Task_2)|Fire PRA Component Selection (Task 2)<br /> ** Fire_PRA_Cable_Selection_(Task 3)|Fire PRA Cable Selection (Task 3)<br /> ** Qualitative Screening (Task 4)|Qualitative Screening (Task 4)<br /> ** Plant_Fire-Induced_Risk_Model_(Task_5)|Plant Fire-Induced Risk Model (Task 5)<br /> ** Fire_Ignition_Frequency_(Task_6)|Fire Ignition Frequency (Task 6)<br /> ** Quantitative_Screening_(Task_7)|Quantitative Screening (Task 7)<br /> ** Scoping_Fire_Modeling_(Task_8)|Scoping Fire Modeling (Task 8)<br /> ** Detailed_Circuit_Failure_Analysis_(Task_9)|Detailed Circuit Failure Analysis (Task 9)<br /> ** Circuit_Failure_Mode_Likelihood_Analysis_(Task_10)|Circuit Failure Mode Likelihood Analysis (Task 10)<br /> ** Detailed_Fire_Modeling_(Task_11)|Detailed Fire Modeling (Task 11)<br /> ** Post-Fire_Human_Reliability_Analysis_(Task_12)|Post-Fire Human Reliability Analysis (Task 12)<br /> ** Seismic_Fire_Interactions_(Task_13)|Seismic Fire Interactions (Task 13)<br /> ** Fire_Risk_Quantification_(Task_14)|Fire Risk Quantification (Task 14)<br /> ** Uncertainty_and_Sensitivity_Analyses_(Task_15)|Uncertainty and Sensitivity Analyses (Task 15)<br /> ** Fire_PRA_Documentation_(Task_16)|Fire PRA Documentation (Task 16)<br /> ** Technology_Transfer|Technology Transfer<br /> * Feedback<br /> ** mailto:crochon@epri.com|Send Feedback<br /> * Exit Wiki<br /> ** https://go.epri.com/signout|Logout</div> User https://firepra.epri.com/index.php?title=Detailed_Fire_Modeling_(Task_11)&diff=1180 Detailed Fire Modeling (Task 11) 2020-06-11T18:35:39Z <p>User: </p> <hr /> <div>[[File:EnclosureDynamics.png|700px||right]] __TOC__ <br /> ==Task Overview==<br /> <br /> ===Background===<br /> This task describes the method to examine the consequences of a fire. This includes consideration of scenarios involving single compartments, multiple fire compartments, and the main control room. Factors considered include initial fire characteristics, fire growth in a fire compartment or across fire compartments, detection and suppression, electrical raceway fire barrier systems, and damage from heat and smoke. Special consideration is given to turbine generator (T/G) fires, hydrogen fires, high-energy arcing faults, cable fires, and main control board (MCB) fires. There are considerable improvements in the method for this task over the [https://www.epri.com/#/pages/product/TR-100370/ EPRI FIVE] and EPRI's Fire PRA Implementation Guide (TR&amp;#8209;105928, no longer available on epri.com) in nearly all technical areas.<br /> <br /> ===Purpose===<br /> In the preceding tasks, the analyses were organized around compartments, assuming that a fire would have widespread impact within the compartment. In Task&amp;nbsp;11, for those compartments found to be potentially risk-significant (i.e., unscreened compartments), a detailed analysis approach is provided. As part of the detailed analysis, fire growth and propagation is modeled and possibility of fire suppression before damage to a specific target set is analyzed. <br /> <br /> The detailed fire modeling process generally follows a common step structure, but the details of the analyses often vary depending on the specifics of the postulated fire scenario. This task provides separate procedures for three general categories of fire scenarios: fires affecting target sets located inside one compartment (discussed in Section&amp;nbsp;11.5.1); fires affecting the main control room (MCR; Section&amp;nbsp;11.5.2); and fires affecting target sets located in more than one fire compartment (multicompartment fire analysis; Section&amp;nbsp;11.5.3). <br /> <br /> Task&amp;nbsp;11 provides final estimates for the frequency of occurrence of fire scenarios involving a specific fire ignition source failing a predefined target set before fire protection succeeds in protecting the target set. This result is combined in the final quantification steps that follow this task, with the CCDP/CLERP given failure of the target set to estimate the CDF/LERF contribution for each fire scenario. The CCDP/CLERP may include modified human error probabilities based on fire scenario specifics.<br /> <br /> ===Scope===<br /> Detailed fire modeling encompasses an analysis of the physical fire behavior (i.e., fire growth and propagation analysis), equipment damage, fire detection, and fire suppression. The fire scenarios to analyze as part of this detailed analysis task are divided into three categories: <br /> <br /> * ''General single compartment fire scenarios''. This general category covers fire scenarios damaging target sets located within the same compartment, exclusive of those scenarios within or impacting the MCR. In general, in this category, the fire ignition source is in the same compartment as the target set. The majority of fire scenarios analyzed generally falls into this category. The procedures applicable to the analysis of these fire scenarios are presented in Section&amp;nbsp;11.5.1. <br /> * ''MCR fire scenarios''. This general category covers all fires that occur within the MCR. This category also covers scenarios involving fires in compartments other than the MCR that may force MCR abandonment. The MCR analysis procedures are presented in Section&amp;nbsp;11.5.2. <br /> * ''Multicompartment fire scenarios'': This general category covers all fire scenarios where it is postulated that a fire may spread from one compartment to another and damage target elements in multiple compartments. In this category of scenarios, damaging effects of a fire (e.g., heat) are assumed to spread beyond the compartment of fire origin. The multicompartment fire analysis procedures are presented in Section&amp;nbsp;11.5.3. <br /> <br /> A detailed fire modeling analysis is performed for each fire scenario in each unscreened fire compartment. For many compartments, it may be appropriate to develop several fire scenarios to appropriately represent the range of unscreened fire ignition sources (i.e., scenarios that would not screen out in Task&amp;nbsp;8) that might contribute to the fire risk. Detailed fire modeling may utilize a range of tools to assess fire growth and damage behavior, and the fire detection and suppression response, for specific fire scenarios. <br /> <br /> [[File:ScreeningDetailed.png|900px||center]]<br /> <br /> The ultimate output of Task&amp;nbsp;11 is a set of fire scenarios, frequency of occurrence of those scenarios, and a list of target sets (in terms of fire PRA components) associated with the scenarios. For scenarios involving the MCR, the possibility of forced abandonment is also noted. Note that a fire scenario represents a specific chain of events starting with ignition of a fire ignition source, propagation of the fire effects to other items, and possibility of damaging a set of items identified as a target set before successful fire suppression.<br /> <br /> ==Related Element of ASME/ANS PRA Standard==<br /> Fire Scenario Selection (FSS)<br /> <br /> ==Related EPRI&amp;nbsp;1011989 NUREG/CR&amp;#8209;6850 Appendices==<br /> Appendix&amp;nbsp;E, Appendix for Chapters 8 and 11, Severity Factors<br /> <br /> Appendix&amp;nbsp;F, Appendix for Chapter&amp;nbsp;8, Walkdown Forms<br /> <br /> Appendix&amp;nbsp;G, Appendix for Chapters 8 and 11, Heat Release Rates<br /> <br /> Appendix&amp;nbsp;H, Appendix for Chapters 8 and 11, Damage Criteria<br /> <br /> Appendix&amp;nbsp;L, Appendix for Chapter&amp;nbsp;11, Main Control Board Fires<br /> <br /> Appendix&amp;nbsp;M, Appendix for Chapter&amp;nbsp;11, High Energy Arcing Faults<br /> <br /> Appendix&amp;nbsp;N, Appendix for Chapter&amp;nbsp;11, Hydrogen Fires<br /> <br /> Appendix&amp;nbsp;O, Appendix for Chapter&amp;nbsp;11, Turbine Generator Fires<br /> <br /> Appendix&amp;nbsp;P, Appendix for Chapter&amp;nbsp;11, Detection and Suppression Analysis<br /> <br /> Appendix&amp;nbsp;Q, Appendix for Chapter&amp;nbsp;11, Passive Fire Protection Features<br /> <br /> Appendix&amp;nbsp;R, Appendix for Chapter&amp;nbsp;11, Cable Fires<br /> <br /> Appendix&amp;nbsp;S, Appendix for Chapter&amp;nbsp;11, Fire Propagation to Adjacent Cabinets<br /> <br /> Appendix&amp;nbsp;T, Appendix for Chapter&amp;nbsp;11, Smoke Damage<br /> <br /> ==Fire Modeling Tools==<br /> <br /> Fire modeling tools include a range of complexity, from Excel-based tools which rely on physics-based algebraic relationships such as EPRI FIVE and the NRC FDT&lt;sup&gt;s&lt;/sup&gt;, to moderately complex tools such as CFAST's two-zone computational model, up to the most complex (and computationally-demanding) finite element analysis tools such as FDS.<br /> <br /> ===Fire Model Verification and Validation===<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1824/ NUREG&amp;#8209;1824 EPRI&amp;nbsp;1011999] documents the verification and validation (V&amp;V) of five fire models that are commonly used in NPP applications. The models in the V&amp;V report include:<br /> *NRC's NUREG&amp;#8209;1805 Revision&amp;nbsp;1<br /> *EPRI's Fire-Induced Vulnerability Evaluation Revision&amp;nbsp;1 (FIVE-REV 1)<br /> *National Institute of Standards and Technology's (NIST) Consolidated Model of Fire Growth and Smoke Transport (CFAST) Version 5<br /> *NIST's Fire Dynamics Simulator (FDS) Version 4<br /> *Electricite de France's (EdF) MAGIC Version 4.1.1<br /> <br /> [https://www.epri.com/#/pages/product/000000003002002182/?lang=en-US NUREG&amp;#8209;1824 Supplement&amp;nbsp;1 EPRI&amp;nbsp;3002002182] updates the original NUREG&amp;#8209;1824 / EPRI&amp;nbsp;1011999 report with additional experiments and uses the latest versions of the fire modeling software available at the time of publication. The models in the V&amp;V report include:<br /> *NRC's Fire Dynamics Tools (FDT&lt;sup&gt;s&lt;/sup&gt; Version 1805.1)<br /> *EPRI's Fire-Induced Vulnerability Evaluation (FIVE Revision&amp;nbsp;2)<br /> *NIST's CFAST Version 7.0.0<br /> *EdF's MAGIC Version 4.1.3<br /> *NIST's FDS Version 6.2.0<br /> <br /> ===Fire Models Included in V&amp;V Guidance===<br /> [https://www.epri.com/#/pages/product/000000003002000830/?lang=en-US EPRI FIVE]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/ NRC Fire Dynamics Tools - NUREG&amp;#8209;1805]<br /> <br /> [https://www.nist.gov/el/fire-research-division-73300/product-services/consolidated-fire-and-smoke-transport-model-cfast NIST CFAST]<br /> <br /> [https://pages.nist.gov/fds-smv/ NIST FDS and Smokeview]<br /> <br /> EdF's MAGIC is available through EPRI for EPRI members<br /> <br /> ===Fire Model User's Guide===<br /> <br /> [https://www.epri.com/#/pages/product/000000000001023259/?lang=en-US NUREG&amp;#8209;1934 EPRI&amp;nbsp;1023259] provides guidance on the proper application of fire models to nuclear power plant fire scenarios. Eight (8) different example fire scenarios are developed and discussed in this report.<br /> <br /> ==Ignition Source Specific Fire Modeling Guidance==<br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! Bin<br /> ! Plant Location<br /> ! Ignition Source<br /> ! Fire Modeling Guidance<br /> ! Fire Modeling Reference<br /> <br /> |-<br /> | 1<br /> | Battery Room<br /> | Batteries<br /> | Use HRR distribution for Motors (Distribution 7 of Table G-1)<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 2<br /> | Containment (PWR)<br /> | Reactor Coolant Pumps<br /> | Reactor coolant pump fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.14 electrical / 0.86 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 3<br /> | Containment (PWR)<br /> | Transients and Hotwork<br /> | &lt;div id=&quot;FMBin3&quot;&gt;&lt;/div&gt;NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distributions and zones of influence for generic transient fires and also transient combustible control locations (TCCLs). These HRRs are based upon the laboratory testing conducted by EPRI and the NRC on relevant transient ignition sources expected in nuclear power plants (see EPRI&amp;nbsp;3002015997 / NUREG&amp;#8209;2232). The HRR distribution (Distribution&amp;nbsp;8 of Table&amp;nbsp;G&amp;#8209;1 in NUREG/CR&amp;#8209;6850) is bounding compared with the updated generic HRR distribution, and is therefore still valid.<br /> <br /> NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 also recommends fire modeling parameters including fire growth and decay parameters, yields of minor products of combustion, heat of combustion, and the physical size and effective elevation of the fire.<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> <br /> |-<br /> | 4<br /> | Control Room<br /> | Main Control Board<br /> | '''Target damage:''' Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 provides a statistical model for estimating the conditional probability of damage to a set of target items inside the main control board.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt;<br /> <br /> '''Target damage:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;7 provides an alternative to the method described in Appendix&amp;nbsp;L of NUREG/CR&amp;#8209;6850 for evaluating the risk of fire events originating in the MCB, whereby MCB fire scenarios are modeled as a progression of damage states using an event tree model.&lt;sup&gt;&amp;nbsp;&amp;sect;&lt;/sup&gt; In this formulation, each damage state requires the definition of a target set, which consists of one or more MCB functions that can be damaged by fire. The functions within the scope of this analysis are those that are represented with basic events in the plant response model and supported with cables routed within the MCB. The alternative model described in this guidance explicitly incorporates two characteristics of MCB fires observed in operating experience—relatively small fires in low-voltage panels and the ability for prompt detection and suppression by control room operators. Operating experience suggests that the majority of fires in the MCB are limited to a single subcomponent or group of subcomponents near the point of ignition. In addition, these fires are promptly detected and suppressed by control room operators. Therefore, the event tree model explicitly accounts for the operator’s ability to quickly detect and suppress the fire before growth and/or propagation.<br /> &lt;div style=&quot;font-size:88%; margin-right: 3em; margin-left: 4em; text-indent: -1em;&quot;&gt;&amp;sect;&amp;nbsp;''The original NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;L method and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 event tree method BOTH remain viable as methods for assessing MCB fires.''&lt;/div&gt;<br /> <br /> '''HRR distributions:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated HRR distributions for the main control board based on control cabinet size (either Function Group 4a (Large Enclosures) or Group 4b (Medium Enclosures)).<br /> <br /> '''Propagation to adjacent cabinet:''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 5<br /> | Control/Aux/Reactor Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 6<br /> | Control/Aux/Reactor Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 7<br /> | Control/Aux/Reactor Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 8<br /> | Diesel Generator Room<br /> | Diesel Generators<br /> | There is limited guidance on modeling diesel generator fires in NUREG/CR-6850:<br /> * Diesel generator fires have an electrical (motor) component and an oil component. The split fraction between electrical and oil fires is provided in NUREG/CR‑6850 (0.16 electrical / 0.84 oil).<br /> * Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 provides guidance on flammable liquid (oil) fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 9<br /> | Plant-Wide Components<br /> | Air Compressors<br /> | Air compressor fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.83 electrical / 0.17 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 10<br /> | Plant-Wide Components<br /> | Battery Chargers<br /> | Table&amp;nbsp;7&amp;#8209;1 of NUREG&amp;#8209;2178 Volume&amp;nbsp;1 provides HRR distributions for Group 2 electrical enclosures, including battery chargers.<br /> | [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> |-<br /> | 11<br /> | Plant-Wide Components<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 12<br /> | Plant-Wide Components<br /> | Cable Run (self-ignited cable fires)<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 13<br /> | Plant-Wide Components<br /> | Dryers<br /> | The transient HRR is recommended for Bin&amp;nbsp;13 dryer fires (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231 provides updated HRR distribution and zones of influence for generic transient fires (see also [[#FMBin3|Bin&amp;nbsp;3]]).<br /> <br /> | [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231]<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6850/s1/cr6850s1.pdf NUREG/CR&amp;#8209;6850 / EPRI&amp;nbsp;1011989]<br /> |-<br /> | 14<br /> | Plant-Wide Components<br /> | Electric Motors<br /> | &lt;div id=&quot;FMBin14&quot;&gt;&lt;/div&gt;Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for electric motors (compared with the original distribution from NUREG/CR&amp;#8209;6850 Table G-1). To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 15<br /> | Plant-Wide Components<br /> | Electrical Cabinets<br /> | &lt;div id=&quot;FmBin15&quot;&gt;'''Propagation from electrical cabinets: ''' FAQ&amp;nbsp;08&amp;#8209;0042 (Section&amp;nbsp;8 of Supplement&amp;nbsp;1) clarifies the treatment of fire spread beyond the ignition source for electrical cabinets considering conditions such as the presence of ventilation, robust door construction, and seal penetration. This clarification was needed due to conflicting language in Chapters 6 and 11 and Appendix&amp;nbsp;G of NUREG/CR&amp;#8209;6850. FAQ&amp;nbsp;08&amp;#8209;0042 states that the wording in Chapter&amp;nbsp;11 is correct.<br /> <br /> '''Propagation to adjacent cabinet: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;4 provides a method for refining the postulated spread of fires from one cabinet to an adjacent cabinet. This report provides screening guidance, a conditional probability (split fraction), a limitation of spread to a single adjacent cabinet only, and timing for the spread.<br /> <br /> '''Propagation for Well-Sealed MCCs Greater Than 440V:''' FAQ&amp;nbsp;14&amp;#8209;0009 provides clarification for the treatment of fire propagation from well-sealed MCCs operating at greater than 440V.<br /> <br /> '''Heat Release Rates: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 provides updated heat release distributions for electrical enclosures. The analyst should review the equipment function or size to determine an appropriate heat release rate distribution provided in Table 7-1. Heat release rates for electrical cabinets are also found in Table G-1 of EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850.<br /> <br /> '''Fire location: ''' FAQ&amp;nbsp;08&amp;#8209;0043 clarifies the treatment of fire location in electrical cabinets. <br /> <br /> '''Fire diameter: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;4.2 provides guidance on the selection of an appropriate fire diameter. <br /> <br /> '''Obstructed plume model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578 Section&amp;nbsp;6 provides a method to account for the impact of the enclosure on the vertical thermal zone of influence above the enclosure during a fire. A summary of the obstructed plume methodology and the results can be found [https://firepra.epri.com/index.php?title=Obstructed_Plume here].<br /> <br /> '''Obstructed radiation model: ''' NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 Section&amp;nbsp;3 provides a method to account for the impact of the enclosure on the horizontal (radial) zone of influence surrounding the enclosure during a fire. This report establishes values for the ZOI measured from the cabinet face<br /> as a function of the cabinet type, cable type, fuel loading, and fire size.<br /> <br /> '''Growth and suppression: ''' NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051 includes the following updates:<br /> :1) Updated fire ignition frequency ([[Fire Ignition Frequency (Task 6)#IgnBin15|Task&amp;nbsp;6]])<br /> :2) Classification of electrical cabinet fires into one of two profiles:<br /> ::::{| class=&quot;wikitable&quot; style=&quot;line-height:110%&quot;<br /> |-<br /> | Interruptible fires<br /> | 0.723<br /> |-<br /> | Growing fires<br /> | 0.277<br /> |}<br /> :3) HRR timing for interruptible and growing fires:<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;1:&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 9 minutes<br /> |-<br /> | Growth<br /> | 7 minutes<br /> |-<br /> | Steady state<br /> | 5 minutes<br /> |-<br /> | Decay<br /> | 13 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Interruptible fires – Option&amp;nbsp;2:&lt;br&gt;(NUREG/CR&amp;#8209;6850 timing profile supplemented with pre-growth period)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Pre-growth (negligible HRR)<br /> | 4 minutes<br /> |-<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :::&lt;p style=&quot;line-height:110%; margin-left: 2em; text-indent:-2em&quot;&gt;Growing fires:&lt;br&gt;&amp;emsp;(unchanged from NUREG/CR&amp;#8209;6850)&lt;/p&gt;<br /> ::::{| class=&quot;wikitable&quot;<br /> | Growth<br /> | 12 minutes<br /> |-<br /> | Steady state<br /> | 8 minutes<br /> |-<br /> | Decay<br /> | 19 minutes<br /> |}<br /> :4) Changes to the detection-suppression event tree to better represent the operating experience. <br /> :The detection-suppression event tree was revised to better represent the manual suppression outcomes observed in operating experience (including the development of two new manual suppression curves). See EPRI&amp;nbsp;3002016051 / NUREG&amp;#8209;2230 for full details.<br /> <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0042, Section&amp;nbsp;8 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.nrc.gov/docs/ML1511/ML15119A176.html FAQ&amp;nbsp;14&amp;#8209;0009]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0043, Section&amp;nbsp;12 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> |-<br /> | 16.a<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Low Voltage Electrical Cabinets (480-1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from High Energy Arcing Faults (HEAFs).<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.b<br /> | Plant-Wide Components<br /> | High Energy Arcing Faults - Medium Voltage Electrical Cabinets (&gt;1000 V)<br /> | Appendix&amp;nbsp;M (M.4.2) provides an empirical model for determination of the ZOI from HEAFs. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 16.1<br /> | Plant-Wide Components<br /> | HEAF for segmented bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for segmented bus duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 16.2<br /> | Plant-Wide Components<br /> | HEAF for iso-phase bus ducts<br /> | Section&amp;nbsp;7.2.1.5 of Supplement&amp;nbsp;1 (FAQ 07-0035) provides an empirical model for estimating the ZOI for iso-phase duct fires. <br /> | [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ 07-0035, Section&amp;nbsp;7 of Supplement&amp;nbsp;1]<br /> |-<br /> | 17<br /> | Plant-Wide Components<br /> | Hydrogen Tanks<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 18<br /> | Plant-Wide Components<br /> | Junction Boxes<br /> | FAQ&amp;nbsp;13&amp;#8209;0006 provides a definition for junction boxes that allows the characterization and quantification of these scenarios in fire compartments that require detailed fire modeling analysis.<br /> |[https://www.nrc.gov/docs/ML1333/ML13331B213.pdf FAQ&amp;nbsp;13&amp;#8209;0006]<br /> |-<br /> | 19<br /> | Plant-Wide Components<br /> | Miscellaneous Hydrogen Fires<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 20<br /> | Plant-Wide Components<br /> | Off-gas/H&lt;sub&gt;2&lt;/sub&gt; Recombiner (BWR)<br /> | See Appendix&amp;nbsp;N of NUREG/CR&amp;#8209;6850.<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 21<br /> | Plant-Wide Components<br /> | Pumps and large hydraulic valves<br /> | &lt;span id=&quot;Bin21&quot;&gt;&lt;/span&gt;Pump fires are classified as either electrical (motor) or oil. The split fraction between pump electrical and oil fires is updated in EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169 (0.69 electrical / 0.31 oil).<br /> <br /> '''Electrical (motor) fires: ''' In NUREG/CR&amp;#8209;6850, Bin 21 pump electrical fires were distinguished from non-pump motor fires. Research documented in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 suggests that there is little or no difference between pump motor fires and non-pump motor fires, and so electric motors and motor-driven pumps have been consolidated into a single ignition source. To improve realism, the HRRs in NUREG&amp;#8209;2178 Volume&amp;nbsp;2 are characterized by horsepower, and NUREG&amp;#8209;2178 Volume&amp;nbsp;2 also provides growth and decay timing. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' The methods panel decision letter (ML12171A583) updates the likelihood and oil spill sizes for general pump oil fires ''other than'' large hydraulic valves. Specifically: <br /> * 88% of oil fires from pumps limit damage to the pump itself,<br /> * 7% of oil fires from pumps produce oil pools of 10% capacity, and<br /> * 5% of oil fires from pumps produce oil pools of 100% capacity.<br /> For large hydraulic valves (which are included in Bin 21), the oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should still be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> <br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US EPRI&amp;nbsp;3002002936 / NUREG&amp;#8209;2169]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> <br /> [https://www.nrc.gov/docs/ML1217/ML12171A583.pdf Methods Panel Decision, ML12171A583]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 22<br /> | Plant-Wide Components<br /> | RPS MG Sets<br /> | The motor HRR is recommended for Bin&amp;nbsp;22 RPS MG Sets (refer to Table&amp;nbsp;11&amp;#8209;1 of NUREG/CR&amp;#8209;6850). See [[#FMBin14|Bin&amp;nbsp;14]].<br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> See [[#FMBin14|Bin&amp;nbsp;14]]<br /> |-<br /> | 23a<br /> | Plant-Wide Components<br /> | Transformers (oil filled)<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 23b<br /> | Plant-Wide Components<br /> | Transformers (dry)<br /> | Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052 provides updated HRR distributions for dry transformers (compared with the original distribution from NUREG&amp;#8209;6850) based on power rating, as well as growth and decay timing.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> |-<br /> | 24<br /> | Plant-Wide Components<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 25<br /> | Plant-Wide Components<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 26<br /> | Plant-Wide Components<br /> | Ventilation Subsystems<br /> | Ventilation subsystem fires are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.95 electrical / 0.05 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052.<br /> <br /> '''Oil fire split fractions:''' The oil spill size fractions recommended in NUREG/CR&amp;#8209;6850 Appendix E.3 should be applied.<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052]<br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 27<br /> | Transformer Yard<br /> | Transformer - Catastrophic<br /> | The catastrophic failure of a large transformer is defined as an energetic failure of the transformer that includes a rupture of the transformer tank, oil spill, and burning oil splattered a distance from the transformer. The analyst should use the frequency and 1.) determine availability of offsite power based on the function of the transformer(s) and 2.) consider propagation to adjacent (not nearby) buildings or components. A propagation path may be considered at the location of open or sealed penetrations, e.g., where a bus-duct enters from the Yard into the Turbine Building. Structural damage need only be considered only where appropriate shields are not present to protected structures and components against blast or debris. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 28<br /> | Transformer Yard<br /> | Transformer - Non Catastrophic<br /> | In this failure, oil does not spill outside the transformer tank and the fire does not necessarily propagate beyond the fire source transformer. Analyst can use all the frequency and assume total loss of the &quot;Transformer/ Switch Yard&quot; or may split this frequency equally among the large transformers of the area and assume loss of each transformer separately. Loss of offsite power should be determined based on the function of the affected transformer(s). <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 29<br /> | Transformer Yard<br /> | Yard Transformers (Others)<br /> | In the screening phase of the project, the analyst may conservatively assign the same frequency to all of the items in this group. If the scenario would not screen out, the frequency may then be divided among the various items in this group. A relative ranking scheme may be used for this purpose. The ranking may be based on the relative characteristics of the item and the analysts' judgment. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 30<br /> | Turbine Building<br /> | Boiler<br /> | See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> |-<br /> | 31<br /> | Turbine Building<br /> | Cable fires caused by welding and cutting<br /> | FAQ&amp;nbsp;13&amp;#8209;0005 provides additional guidance for detailed fire modeling on both self-ignited cable fires and cable fires caused by welding and cutting. This FAQ outlines a more realistic approach for addressing these types of fires in cable trays and suggests replacement text for Section&amp;nbsp;R.1 of NUREG/CR&amp;#8209;6850. However, the current method of evaluating cable fire risk in NUREG/CR&amp;#8209;6850 remains an acceptable approach. <br /> |[https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> [https://www.nrc.gov/docs/ML1331/ML13319B181.pdf FAQ&amp;nbsp;13&amp;#8209;0005]<br /> |-<br /> | 32<br /> | Turbine Building<br /> | Main Feedwater Pumps<br /> | Main feedwater pumps are classified as either electrical (motor) or oil. The split fraction between electrical and oil fires is provided in NUREG/CR&amp;#8209;6850 (0.11 electrical / 0.89 oil).<br /> <br /> '''Electrical (motor) fires: ''' HRR distributions and fire durations are provided in Chapter&amp;nbsp;5 of NUREG&amp;#8209;2178, Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052. The pump HRR in NUREG/CR&amp;#8209;6850 is bounding compared with the updated values, and is therefore still valid.<br /> <br /> '''Oil fire split fractions:''' FAQ&amp;nbsp;08&amp;#8209;0044 (Section&amp;nbsp;9 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) clarifies the severity factors for small fires (0.966 for a leak that impacts the pump), large fires (0.0306 for 10% inventory spill), and very large fires (0.0034 for 100% inventory spill).<br /> <br /> '''Oil fire HRR:''' See Section&amp;nbsp;G.4 of NUREG/CR&amp;#8209;6850 for HRR for flammable liquid fires. EPRI&amp;nbsp;3002005303, although not formally reviewed by the NRC, provides a method to more realistically characterize the HRR profile and duration for liquid spill fires.<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] <br /> <br /> [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> <br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0044, Section&amp;nbsp;9 of Supplement&amp;nbsp;1]<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/?lang=en-US EPRI&amp;nbsp;3002005303]<br /> <br /> |-<br /> | 33<br /> | Turbine Building<br /> | Turbine Generator Excitor<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.1 &amp; Table O-2) recommends assuming the excitor fire is limited to the excitor itself. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 34<br /> | Turbine Building<br /> | Turbine Generator Hydrogen<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.2 &amp; Table O-2) provides guidance for both limited and severe T/G Hydrogen fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 35<br /> | Turbine Building<br /> | Turbine Generator Oil<br /> | Appendix&amp;nbsp;O (Section&amp;nbsp;O.2.3 &amp; Table O-2) provides guidance for both limited and severe T/G oil fires. Table O-2 also provides a conditional probability for a catastrophic T/G fire involving the hydrogen, oil and blade ejection. <br /> | [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850]<br /> |-<br /> | 36<br /> | Turbine Building<br /> | Transient fires caused by welding and cutting<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |-<br /> | 37<br /> | Turbine Building<br /> | Transients<br /> | See [[#FMBin3|Bin&amp;nbsp;3]] for treatment of transient fires.<br /> | See [[#FMBin3|Bin&amp;nbsp;3]]<br /> |}<br /> <br /> ==Recommended HRR Values ==<br /> The following tables summarize the latest research on HRR probability distributions. These distributions were developed to increase realism in modeling electrical cabinet fires and transient fires. As such, HRR probability distributions available in earlier publications (such as Appendix G of NUREG/CR-6850) are bounding. In the case of electric motors and transformers, the latest HRR probability distributions are based on equipment sizes so that the fires can also be realistically characterized.<br /> ===Electrical Cabinets (NUREG&amp;#8209;2178 Volume&amp;nbsp;1)===<br /> [https://www.epri.com/#/pages/product/000000003002005578/?lang=en-US NUREG&amp;#8209;2178 Volume&amp;nbsp;1 / EPRI&amp;nbsp;3002005578] provides HRR distributions for electrical enclosures.<br /> <br /> :{| style=&quot;font-size: 95%; border: 1px solid #a2a9b1; border-collapse: collapse;&quot;<br /> |+ '''Electrical Enclosures'''<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Class / Function Group<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | Enclosure Ventilation&lt;br&gt;(Open or Closed Doors)<br /> ! rowspan=&quot;3&quot; style=&quot;border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &lt;div id=&quot;FuelTypeLoc&quot;&gt;&lt;/div&gt;Fuel Type[[#FuelTypeLegend|&lt;sup&gt;&amp;dagger;&lt;/sup&gt;]]&lt;br&gt;(TS/QTP/SIS or TP Cables)<br /> ! colspan=&quot;12&quot; style=&quot;background-color:#eaecf0;&quot; | Gamma Distribution<br /> |-<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (a) Default<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (b) Low Fuel Loading<br /> ! colspan=&quot;4&quot; style=&quot;border-top: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | (c) Very Low Fuel Loading<br /> |-<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;alpha;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | &amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;beta;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! style=&quot;border-bottom: 1px solid #a2a9b1; border-left: 1px solid #a2a9b1; background-color:#eaecf0;&quot; | ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''1 - Switchgear and Load Centers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.32<br /> | style=&quot;text-align: center;&quot; | 79<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 170<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.99<br /> | style=&quot;text-align: center;&quot; | 44<br /> | style=&quot;text-align: center;&quot; | 60<br /> | style=&quot;text-align: center;&quot; | 170<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;2&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''2 - MCCs and Battery Chargers'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.36<br /> | style=&quot;text-align: center;&quot; | 57<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 130<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 1.21<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 130<br /> |-<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | '''3 - Power Inverters'''<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> | rowspan=&quot;2&quot; colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | rowspan=&quot;4&quot; style=&quot;background-color:#F8F9Fa; text-align: center;&quot; | '''4a - Large Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt;1.42 m&lt;sup&gt;3&lt;/sup&gt; (&gt;50 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 223<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 145<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 400<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 365<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 700<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.26<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 350<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 32<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 75<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 428<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center;&quot; | 1000<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 214<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center;&quot; | 500<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 21<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 75<br /> |-<br /> | rowspan=&quot;4&quot; style=&quot;text-align: center;&quot; | '''4b - Medium Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤1.42 m&lt;sup&gt;3&lt;/sup&gt; (50 ft&lt;sup&gt;3&lt;/sup&gt;) and&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&gt; 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 111<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.27<br /> | style=&quot;text-align: center;&quot; | 51<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Closed<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 73<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 200<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.52<br /> | style=&quot;text-align: center;&quot; | 36<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 100<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TS/QTP/SIS<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.23<br /> | style=&quot;text-align: center;&quot; | 182<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.19<br /> | style=&quot;text-align: center;&quot; | 92<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |-<br /> | style=&quot;text-align: center;&quot; | Open<br /> | style=&quot;text-align: center;&quot; | TP<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.51<br /> | style=&quot;text-align: center;&quot; | 119<br /> | style=&quot;text-align: center;&quot; | 80<br /> | style=&quot;text-align: center;&quot; | 325<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.3<br /> | style=&quot;text-align: center;&quot; | 72<br /> | style=&quot;text-align: center;&quot; | 25<br /> | style=&quot;text-align: center;&quot; | 150<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center;&quot; | 12<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 45<br /> |- style=&quot;background-color:#F8F9Fa;&quot;<br /> | style=&quot;background-color:#F8F9Fa; border-bottom: 1px solid #a2a9b1; text-align: center;&quot; | '''4c - Small Enclosures'''&lt;br&gt;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;≤ 0.34 m&lt;sup&gt;3&lt;/sup&gt; (12 ft&lt;sup&gt;3&lt;/sup&gt;)<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | Not Applicable<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1;&quot; | All<br /> | style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | 0.88<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 12<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 15<br /> | style=&quot;text-align: center; border-bottom: 1px solid #a2a9b1&quot; | 45<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> | colspan=&quot;4&quot; style=&quot;text-align: center; border-left: 1px solid #a2a9b1; border-bottom: 1px solid #a2a9b1&quot; | Not Applicable<br /> |-<br /> | colspan=&quot;15&quot; style=&quot;text-align: center; background: white; padding: 5px; border-bottom: 1px solid white; border-left: 1px solid white; border-right: 1px solid white&quot; | &lt;div id=&quot;FuelTypeLegend&quot;&gt;&lt;/div&gt;&lt;div style=&quot;font-size:88%;&quot;&gt;'''[[#FuelTypeLoc|&amp;dagger;]]''' ''Legend for Fuel Type:'' '''''TS'''&amp;nbsp;=&amp;nbsp;Thermoset, '''TP'''&amp;nbsp;=&amp;nbsp;Thermoplastic, '''QTP'''&amp;nbsp;=&amp;nbsp;Qualified Thermoplastic, '''SIS'''&amp;nbsp;=&amp;nbsp;Synthetic Insulated Switchboard Wire or XLPE-Insulated Conductor''&lt;/div&gt;<br /> |}<br /> <br /> ===Motors and Dry Transformers (NUREG&amp;#8209;2178 Volume&amp;nbsp;2)===<br /> [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] provides HRR distributions for motors and dry transformers.<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Motors'''<br /> ! rowspan=&quot;2&quot; | Motor&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Motor Size&lt;br&gt;(horsepower)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;5-30<br /> | style=&quot;text-align: center;&quot; | 1.34<br /> | style=&quot;text-align: center;&quot; | 3.26<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 15<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;30-100<br /> | style=&quot;text-align: center;&quot; | 1.17<br /> | style=&quot;text-align: center;&quot; | 8.69<br /> | style=&quot;text-align: center;&quot; | 14<br /> | style=&quot;text-align: center;&quot; | 37<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;100<br /> | style=&quot;text-align: center;&quot; | 1.10<br /> | style=&quot;text-align: center;&quot; | 24.19<br /> | style=&quot;text-align: center;&quot; | 37<br /> | style=&quot;text-align: center;&quot; | 100<br /> |}<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Dry Transformers'''<br /> ! rowspan=&quot;2&quot; | Transformer&lt;br&gt;Classification Group<br /> ! rowspan=&quot;2&quot; | Transformer Power&lt;br&gt;(kVA)<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''A'''<br /> | style=&quot;text-align: center;&quot; | &gt;45-75<br /> | style=&quot;text-align: center;&quot; | 0.38<br /> | style=&quot;text-align: center;&quot; | 12.84<br /> | style=&quot;text-align: center;&quot; | 6<br /> | style=&quot;text-align: center;&quot; | 30<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''B'''<br /> | style=&quot;text-align: center;&quot; | &gt;75-750<br /> | style=&quot;text-align: center;&quot; | 0.41<br /> | style=&quot;text-align: center;&quot; | 28.57<br /> | style=&quot;text-align: center;&quot; | 15<br /> | style=&quot;text-align: center;&quot; | 70<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''C'''<br /> | style=&quot;text-align: center;&quot; | &gt;750<br /> | style=&quot;text-align: center;&quot; | 0.46<br /> | style=&quot;text-align: center;&quot; | 50.26<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 130<br /> |}<br /> <br /> ===Transients (NUREG&amp;#8209;2233)===<br /> [https://www.epri.com/#/pages/product/3002018231/ NUREG&amp;#8209;2233 / EPRI&amp;nbsp;3002018231] provides HRR distributions for both generic and &quot;transient combustible control location&quot; (TCCL) type transient fires. The report also provides values for total energy release (TER) and zones of influence (ZOIs), but only HRRs are included here.<br /> :{| class=&quot;wikitable&quot;<br /> |+ '''Transients'''<br /> ! rowspan=&quot;2&quot; | Type<br /> ! colspan=&quot;4&quot; | &lt;p style=&quot;font-size:90%;&quot;&gt;Gamma Distribution&lt;/p&gt;<br /> |-<br /> ! α<br /> ! β<br /> ! ''P&lt;sub&gt;75&lt;/sub&gt;'' (kW)<br /> ! ''P&lt;sub&gt;98&lt;/sub&gt;'' (kW)<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''Generic'''<br /> | style=&quot;text-align: center;&quot; | 0.271<br /> | style=&quot;text-align: center;&quot; | 141<br /> | style=&quot;text-align: center;&quot; | 41.6<br /> | style=&quot;text-align: center;&quot; | 278<br /> |-<br /> | style=&quot;text-align: center;&quot; | '''TCCL'''<br /> | style=&quot;text-align: center;&quot; | 0.314<br /> | style=&quot;text-align: center;&quot; | 67.3<br /> | style=&quot;text-align: center;&quot; | 24.6<br /> | style=&quot;text-align: center;&quot; | 143<br /> |}<br /> <br /> ==Additional Fire Modeling Considerations==<br /> ===Time-to-Damage Models for Cables===<br /> Three approaches are documented for assessing the time-to-damage for cables.<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Exposure threshold'''''<br /> The method described in [https://www.epri.com/#/pages/product/000000000001011989/?lang=en-US EPRI&amp;nbsp;1011989 / NUREG/CR&amp;#8209;6850] Appendix&amp;nbsp;H consists of using the threshold exposure gas temperature or heat flux for determining cable failure. See [[#Fire Damage Criteria|below]] for damage criteria. This is the simplest of the approaches, but it can be fairly conservative because it does not account for the time it takes for cable heating to actually result in damage.<br /> <br /> '''''Heat soak'''''<br /> The method described in Appendix&amp;nbsp;A of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] considers exposure integrated over time based upon the time to failure data provided in Appendix&amp;nbsp;H of NUREG/CR&amp;#8209;6850. This method is less conservative than the above &quot;exposure threshold&quot; method but still conservative when compared with THIEF.<br /> Time to failure data for Kerite-FR materials are provided in [https://www.epri.com/#/pages/product/3002015997/ NUREG&amp;#8209;2232 / EPRI&amp;nbsp;3002015997].<br /> <br /> '''''Heat conduction (Thermally-Induced Electrical Failure, &quot;THIEF&quot;)'''''<br /> The THIEF approach presented in [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr6931/ NUREG/CR&amp;#8209;6931 Volume&amp;nbsp;3] and [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1805/s1/ NUREG&amp;#8209;1805 Supplement&amp;nbsp;1] performs a one-dimensional (1-D), cylindrical heat transfer calculation for a cable exposed to a time-varying exposure to determine when the cable jacket will fail based on the jacket’s inner temperature. Validation of the model shows that it does well at computing the temperature rise of the cable jacket; however, because it requires cable-specific data (dimensions and mass), it cannot be applied in a generic manner such as the exposure threshold or heat soak methods.<br /> &lt;/div&gt;<br /> <br /> ===Location Factor===<br /> When the fire is located near a wall or in a corner, less air can be entrained into the fire plume. Less air entrainment into the fire plume produces higher plume temperatures. The flames from fires in contact with wall and corner surfaces tend to be longer, also resulting in higher plume temperatures. For such fires, a location factor, traditionally 2 for fires near a wall or 4 for fires near a corner, has been applied as a correction to the plume temperature calculation. [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] Section&amp;nbsp;6 demonstrates that the traditional approach is overly conservative, and presents new factors based on the distance from the source to a corner or wall:<br /> <br /> :{| class=&quot;wikitable&quot;<br /> |-<br /> ! rowspan=&quot;2&quot; | Configuration<br /> ! colspan=&quot;3&quot; | Location Factor<br /> |-<br /> ! 0–0.3 m [0–1 ft]<br /> ! 0.3–0.6 m [1–2 ft]<br /> ! &gt;0.6 m [2 ft]<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Corner<br /> | style=&quot;text-align:center;&quot; | 4<br /> | style=&quot;text-align:center;&quot; | 2<br /> | style=&quot;text-align:center;&quot; | 1<br /> |-<br /> ! style=&quot;text-align:center;&quot; | Wall<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> | style=&quot;text-align:center;&quot; | 1<br /> |}<br /> <br /> [https://www.epri.com/#/pages/product/000000003002005303/ EPRI&amp;nbsp;3002005303] provides the technical basis for the work in NUREG&amp;#8209;2178 Volume&amp;nbsp;2.<br /> <br /> ===Radiation effects modeling===<br /> Chapter&amp;nbsp;2 of [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2 / EPRI&amp;nbsp;3002016052] evaluates radiation emission models used to assess horizontal zone of influence. The two commonly-implemented empirical models – the '''point source''' method and the '''solid flame''' method – are compared against a computational model (Fire Dynamics Simulator). The results of this chapter recommended that the adjusted solid flame model should generally be considered a preferred method over the point source method because the adjusted flame model shows somewhat better characteristics in terms of a) NOT under-predicting and b) improved statistical error and bias. This applies to all fire types, where the flame is ''un''obstructed. The modeling of obstructed radiation circumstances as present in electrical cabinets is discussed in the context of [[#FmBin15|Bin 15 electrical cabinet fire modeling]].<br /> <br /> ===High Energy Arcing Fault (HEAF) Research===<br /> EPRI and the NRC are currently developing further methods and data on the risk impact of HEAF events; for example frequencies, fault duration, and zone of influence (e.g., copper versus aluminum). EPRI has issued the following white paper reports:<br /> *[https://www.epri.com/#/pages/product/000000003002015992/ EPRI&amp;nbsp;3002015992] provides an overview of nuclear power station electrical distribution systems and covers fault protection system concepts, fault isolation times, the potential impact of HEAFs on Class&amp;nbsp;1E electrical distribution systems, and typical industry practices and programs that help ensure proper operation. This report also provides some preliminary risk insights based on a review of existing data.<br /> *[https://www.epri.com/#/pages/product/000000003002011922/ EPRI 3002011922] reviews the operating experience to gain insights about equipment type, event characteristics, and the range of damage for HEAF events occurring at nuclear power plants within the United States and internationally. This paper also explores recent U.S. and international HEAF test programs for low- and medium-voltage electrical equipment and summarizes the insights gained from these test programs, including the potential role of aluminum oxidation in HEAF severity. <br /> *[https://www.epri.com/#/pages/product/000000003002015459/ EPRI 3002015459] demonstrates that an effective preventive maintenance program is important in minimizing the likelihood and/or severity of a HEAF event. Sixty&amp;#8209;four percent (64%) of HEAF events were determined to be preventable, and the most prevalent cause of failure was inadequate maintenance. These data demonstrate that proper maintenance can prevent most HEAF events. Effective maintenance practices and strategies are summarized in this report by equipment type, including circuit breakers, bus ducts, protective relays, and cables.<br /> <br /> ==Fire Propagation and Suppression Guidance==<br /> ===Detection-Suppression Event Tree===<br /> For electrical cabinet fires, Section&amp;nbsp;5 of [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230 / EPRI&amp;nbsp;3002016051] presents a revised detection-suppression event tree model for characterizing fire detection and suppression activities in response to a fire event (revised compared with the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1). This modification is intended to capture the potential for plant personnel suppression during the early stages of an electrical cabinet fire. For other fire types, the original model described in Appendix&amp;nbsp;P of NUREG/CR&amp;#8209;6850 and Chapter&amp;nbsp;14 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1 should be used.<br /> <br /> ===Fire Damage Criteria===<br /> &lt;div style=&quot;margin:1em&quot;&gt;<br /> '''''Cable Damage Criteria'''''<br /> <br /> [https://www.nrc.gov/docs/ML1807/ML18074A023.html FAQ&amp;nbsp;16&amp;#8209;0011] provides radiant heating and temperature criteria for bulk cable tray ignition (which was not previously provided in NUREG/CR&amp;#8209;6850). The bounding cable damage and ignition criteria remain the same. A summary of the results are shown below. The analyst should refer to both NUREG/CR&amp;#8209;6850 Appendix&amp;nbsp;H and FAQ&amp;nbsp;16&amp;#8209;0011 for full guidance.<br /> <br /> {| class=&quot;wikitable&quot;<br /> |-<br /> ! <br /> !colspan=&quot;2&quot;| Bounding Cable Damage / Ignition Criteria<br /> !colspan=&quot;2&quot;| Bulk Cable / Tray Ignition Criteria<br /> |-<br /> ! Cable Type<br /> ! Radiant Heating <br /> ! Temperature<br /> ! Radiant Heating<br /> ! Temperature<br /> |-<br /> ! Thermoplastic<br /> | style=&quot;text-align: center | 6 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 205°C<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 25 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | rowspan=&quot;2&quot; style=&quot;text-align: center;&quot; | 500°C<br /> |-<br /> ! Thermoset<br /> | style=&quot;text-align: center | 11 kW/m&lt;sup&gt;2&lt;/sup&gt;<br /> | style=&quot;text-align: center | 330°C<br /> |}<br /> <br /> For Kerite cables, refer to [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7102/ NUREG/CR&amp;#8209;7102] for damage criteria. Originally FAQ&amp;nbsp;08&amp;#8209;0053 was initiated to clarify failure thresholds for Kerite cables and the resolution can be found in the [https://www.nrc.gov/docs/ML1214/ML121440155.pdf closure memo dated June 6, 2012] following the publication of NUREG/CR&amp;#8209;7102. <br /> <br /> '''''Treatment of Sensitive Electronics'''''<br /> <br /> [https://www.nrc.gov/docs/ML1332/ML13322A085.pdf FAQ&amp;nbsp;13&amp;#8209;0004] provides supplemental guidance for the application of the lower damage thresholds provided in NUREG/CR&amp;#8209;6850 Section&amp;nbsp;8.5.1.2 and H.2 for solid-state components. Fire Dynamics Simulator (FDS) modeling results support the recommendation that a generic screening heat flux damage threshold for thermoset cables, as observed on the outer surface of the cabinet, can be used as a conservative surrogate for assessing the potential for thermal damage to solid-state and sensitive electronics within an electrical panel (cabinet). Since the conclusions of the FDS analysis are based on heat flux exposure to the cabinet, the 65°C temperature damage criterion must still be assessed for other types of fire exposures to the enclosed sensitive electronics.<br /> &lt;/div&gt;<br /> <br /> ===Cable Tray Fire Propagation===<br /> [[File:TrayFireTesting.png|frameless||right||upright=1.7||alt=Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1|||Multiple horizontal cable tray test, image from Chanter 8 of NUREG/CR&amp;#8209;7010 Volume&amp;nbsp;1]]<br /> [https://www.epri.com/#/pages/product/000000000001019259/?lang=en-US FAQ&amp;nbsp;08&amp;#8209;0049, Section&amp;nbsp;11 of Supplement&amp;nbsp;1] clarifies the limits of the empirical cable tray fire propagation model in EPRI&amp;nbsp;1011989, NUREG/CR&amp;#8209;6850. The model can lead to conservative estimates of cable fire growth rates and unrealistically short room burnout times when used outside the ZOI (i.e., outside the fire plume that extends above the ignition source).<br /> <br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7010/ NUREG/CR&amp;#8209;7010] documents the results of experiments to better understand and quantify the burning characteristics of grouped electrical cables commonly found in nuclear power plants. Volume&amp;nbsp;1 studies horizontal cable trays and Volume&amp;nbsp;2 studies vertical shafts and corridors. The experiments in Volume&amp;nbsp;1 address horizontal, ladder-back trays filled with unshielded cables in open configurations. The results of the full-scale experiments have been used to validate a simple model called FLASH&amp;#8209;CAT (Flame Spread over Horizontal Cable Trays). The document also provides verification and validation material for the FLASH&amp;#8209;CAT model. Volume&amp;nbsp;2 performed experiments on vertical cable tray configurations and enclosure effects. Volume&amp;nbsp;2 also extends the FLASH&amp;#8209;CAT model to address cable trays within enclosures and vertical tray configurations.<br /> &lt;br style=&quot;clear: both;&quot; /&gt;<br /> <br /> ===Manual Non-Suppression Probability Estimates===<br /> Various reports have documented updates to the manual non-suppression probability data. The latest updates for each event type are summarized below.<br /> {| class=&quot;wikitable&quot;<br /> |+ style=&quot;text-align: center;&quot; | Probability Distribution for Rate of Fires Suppressed Per Unit Time, λ<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Suppression Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Number of Events&lt;br&gt;in Curve<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Total Duration&lt;br&gt;(minutes)<br /> ! colspan=&quot;4&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Rate of Fire Suppressed (λ)<br /> ! rowspan=&quot;2&quot; style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Calculation Source Document<br /> |-<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | Mean<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;5&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;50&lt;/sub&gt;''<br /> | style=&quot;text-align: center; font-weight:bold; background-color:#dee2e6;&quot; | ''P&lt;sub&gt;95&lt;/sub&gt;''<br /> |-<br /> | Turbine-generator fires<br /> | style=&quot;text-align: center;&quot; | 30<br /> | style=&quot;text-align: center;&quot; | 1167<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.026<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.019<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.025<br /> | style=&quot;text-align: center; padding: 0 1em 0 1em;&quot; | 0.034<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Control room<br /> | style=&quot;text-align: center;&quot; | 10<br /> | style=&quot;text-align: center;&quot; | 26<br /> | style=&quot;text-align: center;&quot; | 0.385<br /> | style=&quot;text-align: center;&quot; | 0.209<br /> | style=&quot;text-align: center;&quot; | 0.372<br /> | style=&quot;text-align: center;&quot; | 0.604<br /> | [https://www.epri.com/#/pages/product/000000003002016052/ NUREG&amp;#8209;2178 Volume&amp;nbsp;2]<br /> |-<br /> | Pressurized water reactor containment (at power)<br /> | style=&quot;text-align: center;&quot; | 3<br /> | style=&quot;text-align: center;&quot; | 40<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.020<br /> | style=&quot;text-align: center;&quot; | 0.067<br /> | style=&quot;text-align: center;&quot; | 0.157<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Containment (low power-shutdown)<br /> | style=&quot;text-align: center;&quot; | 31<br /> | style=&quot;text-align: center;&quot; | 299<br /> | style=&quot;text-align: center;&quot; | 0.104<br /> | style=&quot;text-align: center;&quot; | 0.075<br /> | style=&quot;text-align: center;&quot; | 0.103<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Outdoor transformers<br /> | style=&quot;text-align: center;&quot; | 24<br /> | style=&quot;text-align: center;&quot; | 928<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.018<br /> | style=&quot;text-align: center;&quot; | 0.026<br /> | style=&quot;text-align: center;&quot; | 0.035<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Flammable gas<br /> | style=&quot;text-align: center;&quot; | 8<br /> | style=&quot;text-align: center;&quot; | 234<br /> | style=&quot;text-align: center;&quot; | 0.034<br /> | style=&quot;text-align: center;&quot; | 0.017<br /> | style=&quot;text-align: center;&quot; | 0.033<br /> | style=&quot;text-align: center;&quot; | 0.056<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Oil fires<br /> | style=&quot;text-align: center;&quot; | 50<br /> | style=&quot;text-align: center;&quot; | 562<br /> | style=&quot;text-align: center;&quot; | 0.089<br /> | style=&quot;text-align: center;&quot; | 0.069<br /> | style=&quot;text-align: center;&quot; | 0.088<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Cable fires<br /> | style=&quot;text-align: center;&quot; | 4<br /> | style=&quot;text-align: center;&quot; | 29<br /> | style=&quot;text-align: center;&quot; | 0.138<br /> | style=&quot;text-align: center;&quot; | 0.047<br /> | style=&quot;text-align: center;&quot; | 0.127<br /> | style=&quot;text-align: center;&quot; | 0.267<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | &lt;div id=&quot;ECabLoc&quot;&gt;&lt;/div&gt;Electrical fires [[#ECabNote|&lt;sup&gt;&amp;Dagger;&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 74<br /> | style=&quot;text-align: center;&quot; | 653<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.093<br /> | style=&quot;text-align: center;&quot; | 0.113<br /> | style=&quot;text-align: center;&quot; | 0.136<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Interruptible fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 288<br /> | style=&quot;text-align: center;&quot; | 0.149<br /> | style=&quot;text-align: center;&quot; | 0.114<br /> | style=&quot;text-align: center;&quot; | 0.148<br /> | style=&quot;text-align: center;&quot; | 0.189<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Growing fires (Bin 15)<br /> | style=&quot;text-align: center;&quot; | 18<br /> | style=&quot;text-align: center;&quot; | 179.5<br /> | style=&quot;text-align: center;&quot; | 0.100<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.098<br /> | style=&quot;text-align: center;&quot; | 0.142<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | Welding fires<br /> | style=&quot;text-align: center;&quot; | 52<br /> | style=&quot;text-align: center;&quot; | 484<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.084<br /> | style=&quot;text-align: center;&quot; | 0.107<br /> | style=&quot;text-align: center;&quot; | 0.133<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | Transient fires<br /> | style=&quot;text-align: center;&quot; | 43<br /> | style=&quot;text-align: center;&quot; | 386<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.085<br /> | style=&quot;text-align: center;&quot; | 0.111<br /> | style=&quot;text-align: center;&quot; | 0.141<br /> | [https://www.epri.com/#/pages/product/000000003002002936/?lang=en-US NUREG&amp;#8209;2169]<br /> |-<br /> | HEAFs<br /> | style=&quot;text-align: center;&quot; | 11<br /> | style=&quot;text-align: center;&quot; | 385<br /> | style=&quot;text-align: center;&quot; | 0.029<br /> | style=&quot;text-align: center;&quot; | 0.016<br /> | style=&quot;text-align: center;&quot; | &lt;div id=&quot;028&quot;&gt;&lt;/div&gt;0.028[[#028Note|&lt;sup&gt;^&lt;/sup&gt;]]<br /> | style=&quot;text-align: center;&quot; | 0.044<br /> | [https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ&amp;nbsp;17&amp;#8209;0013]<br /> |-<br /> | All fires<br /> | style=&quot;text-align: center;&quot; | 401<br /> | style=&quot;text-align: center;&quot; | 5661<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.065<br /> | style=&quot;text-align: center;&quot; | 0.071<br /> | style=&quot;text-align: center;&quot; | 0.077<br /> | [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230]<br /> |-<br /> | colspan=&quot;8&quot; style=&quot;background-color:#ffffff; border-bottom: 0.5px solid white; border-left: 0.5px solid white; border-right: 0.5px solid white;&quot; | &lt;div id=&quot;ECabNote&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#ECabLoc|&amp;Dagger;]] ''Electrical fires include non-cabinet electrical sources, such as electrical motors, indoor transformers, and junction boxes, among other electrical equipment.''&lt;/div&gt;<br /> &lt;div id=&quot;028Note&quot; style=&quot;font-size:88%; margin-right: 2em; margin-left: 2em; text-indent: -1em;&quot;&gt;[[#028|^]] ''[https://www.nrc.gov/docs/ML1807/ML18075A086.html FAQ 17-0013] reported the 50th percentile as 0.029. When calculated using the chi-squared distribution the calculated 50th percentile 0.028 as shown in [https://www.epri.com/#/pages/product/000000003002016051/ NUREG&amp;#8209;2230].''&lt;/div&gt;<br /> |}<br /> <br /> ===Incipient Detection===<br /> [https://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr2180/ NUREG&amp;#8209;2180] NRC guidance on crediting incipient detection systems in fire PRA is discussed in NUREG&amp;#8209;2180. The issuance of NUREG&amp;#8209;2180 retires FAQ&amp;nbsp;08&amp;#8209;0046 (Chapter&amp;nbsp;13 of NUREG/CR&amp;#8209;6850 Supplement&amp;nbsp;1) as documented in the [https://www.nrc.gov/docs/ML1616/ML16167A444.pdf July 1, 2016 letter to NEI].</div> User https://firepra.epri.com/index.php?title=MediaWiki:Lastmodifiedat&diff=1177 MediaWiki:Lastmodifiedat 2020-05-21T20:20:01Z <p>User: </p> <hr /> <div>This page was last edited on $1, at $2.<br /> <br /> <br /> EPRI 3420 Hillview Avenue, Palo Alto, California 94304 | 800-313-3774 &lt;br&gt;<br /> © Electric Power Research Institute, Inc. 2001-{{CURRENTYEAR}}. All rights reserved</div> User https://firepra.epri.com/index.php?title=MediaWiki:Lastmodifiedat&diff=1176 MediaWiki:Lastmodifiedat 2020-05-21T19:33:00Z <p>User: </p> <hr /> <div>This page was last edited on $1, at $2.<br /> <br /> <br /> EPRI 3420 Hillview Avenue, Palo Alto, California 94304 | 800-313-3774 &lt;br&gt;<br /> © Electric Power Research Institute, Inc. 2001-2020. 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