Fire Ignition Frequency (Task 6)

Task Overview

Background

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).

Purpose

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.

Scope

This work package addresses the following fire-ignition frequency related issues:

• Plant specific fire event data review and generic fire frequency update using Bayesian approach,
• Equipment (ignition source) count by compartment,
• Apportioning of ignition frequencies according to compartment-specific configurations, and
• Uncertainty considerations in the fire frequencies.

Related Element(s) of ASME/ANS PRA Standard, ASME-RA-Sb-2013

Fire Ignition Frequency (IGN)

Related EPRI 1011989 NUREG/CR-6850 Appendices

Appendix C, Appendix for Chapter 6, Determination of Generic Fire Frequencies

Appendix F, Appendix for Chapter 8, Walkdown Forms