Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
or on operator actions. Where applicable, reviewers should also evaluate the modeling and quantification of the effects of the change ensure that the models are appropriate and that the results can be supported by plant and/or industry data. 111.2.2.2 Scope of Analysis The necessary scope of a F'RA supporting risk-informed requests will depend on the specific application. Although the assessment of risk implications (in light of the acceptance guidelines defined in RG 1. 174) requires that all plant operating modes and initiating events be addressed, it is not necessary in risk-informed regulation that licensees submit PRAs that treat all plant operating modes and all initiating events. Instead, when full-scope PRAs are not available, reviewers should ensure that the submitted findings are supportable on the basis of traditional engineering analyses or other plant operational information addressing modes and initiators not analyzed in the base PRA. SRP 19-14 I For plant modes and initiators not analyzed in the PRA (such as shutdown, seismic events, fire, floods and severe weather), the licensee should consider the effects of the change and provide the rationale for why additional PRA analyses are not necessary. This rationale could be addressed by assessing the level of redundancy and diversity provided by the plant systems, system trains, human actions, etc. for responding to these unanalyzed initiating events. The licensee should also show that the proposed change does not introduce unanalyzed vulnerabilities and that redundancy and diversity will still exist in the plant response capability after the changes are implemented. This issue is addressed acceptably if the proposal fulfills any one of the following criteria: * The licensee addresses all modes and all initiator types using PRA. The licensee demonstrates that the application does not unacceptably degrade plant capability and does not introduce risk vulnerabilities or remove elements of the plant response