Document: NRC Regulatory Guide
Document ID: cde52d5a-adf9-49be-9d1f-59449dfca895
Document Type: regulatory_guide
Title: TRIAL - Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2123/ML21235A008.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.247
CFR Part: 
CFR Title: 

Content:
ation PRA analysis element are as follows: • For each internal fire scenario, the internal fire risk results are quantified by combining the internal fire ignition frequency, the probability of fire damage, and the conditional probability of the event sequence from the internal fire PRA plant response model for a particular POS. • Total risk is calculated for the plant, and risk-significant contributors to event sequences are identified. • Identified dependencies are addressed. • Uncertainties in the internal fire PRA for a POS are characterized. The potential impact of sources of model uncertainty and related assumptions on the results are justified. • Internal fire scenarios may be screened out in the internal fire event sequence quantification PRA analysis element based on preestablished screening criteria for all POSs. C.1.3.10 Seismic Probabilistic Risk Assessment Element This section identifies the hazard group-specific PRA analysis elements, the objectives of those analysis elements, and the characteristics and attributes that are needed for an acceptable seismic NLWR PRA that addresses all radiological sources, all POSs, and all levels of PRA analysis. The objective of each seismic PRA analysis element is briefly described, and the characteristics and attributes needed to achieve the objective are provided. It is assumed that the seismic PRA for a given POS is based on modifications made to a corresponding up-to-date internal events PRA. The seismic PRA analysis element is evaluated for all POSs and may have different characteristics across POSs. The following are the seismic PRA analysis elements, applicable to all phases leading up to and including the as-built, as-operated plant: RG 1.247, Page 33 • seismic hazard analysis, • seismic fragility analysis, and • seismic plant response analysis. Earthquakes can cause initiating events different from those considered in an internal events PRA and can cause simultaneous failures of multiple