Uncertainty and Sensitivity Analyses (Task 15)

Task Overview

Background

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).

Purpose

This procedure describes the approach for identifying and treating uncertainties throughout the Fire PRA process and identifying sensitivity analysis cases. It also prescribes a review for the identified uncertainties among the Fire PRA analysts to establish an integrated approach of addressing the effects of these uncertainties on the results of the analysis. At this time, the procedure provides a general approach to be followed and does not provide a comprehensive list of specific uncertainties to be addressed. As pilot Fire PRAs and other studies are completed, this procedure may be revised accordingly.

Scope

This procedure covers the identification and treatment of uncertainties throughout the Fire PRA. As such, it provides: (1) background on the subject of uncertainty found in Appendix U, (2) classification of types of uncertainty, and (3) a general approach with regard to practical implementation of treating expected uncertainties in the Fire PRA, as described in Appendix V.

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

Uncertainty and Sensitivity Analysis (UNC)

Related EPRI 1011989 NUREG/CR-6850 Appendices

Appendix U, Appendix for Chapter 15, Uncertainty Analysis-Technical Bases

Appendix V, Appendix for Chapter 15, Discussion of Individual Task Uncertainties