Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
oduced into the plant response model resulting strictly from fire-related emergency procedures and those actions retained from the internal events PRA. The latter HFEs are modified to account for fire effects. Fire risk quantification calculates the fire-induced CDF and LERF/LRF contributions to plant risk and identifies significant contributors to each. In this element, the plant response model is quantified for the set of fire scenarios to produce conditional core damage probability and conditional large early release probability (CLERP) or conditional large release probability (CLRP) values. The conditional core damage probability and CLERP/CLRP values are mathematically combined with the corresponding fire ignition frequencies and the conditional probabilities of fire damage for the appropriate fire scenario to yield fire-induced CDF and LERF/LRF. Seismic/fire interactions is a qualitative review of the plant fire risk caused by a potential earthquake. This element seeks to ensure that such seismic/fire interactions have been considered and their impacts assessed. Table 5. Summary of Technical Characteristics and Attributes of an Internal Fire PRA for the At-Power Operating Mode Element Technical Characteristics and Attributes Plant Boundary Definition and Partitioning • Global analysis boundary captures all plant locations relevant to the fire PRA. • Physical analysis units are identified by credited partitioning elements that are capable of substantially confining fire damage behaviors. Equipment Selection • Equipment is selected for inclusion in the plant response model that leads to a fire-induced plant initiator, or that is needed to respond to such an initiator (including equipment subject to fire-induced spurious actuation that affects the plant response). • The number of spurious actuations to be addressed increases according to the significance of the consequence (e.g., interfacing systems LOCA). • Instrumentation and support equipment are