Document: NUREG-0800
Document ID: 7916b088-fb90-4163-84fe-027bd315bcc5
Document Type: srp
Title: REVIEW OF RISK INFORMATION USED TO SUPPORT PERMANENT PLANT-
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0717/ML071700658.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.2
CFR Part: 
CFR Title: 

Content:
to the plant’s estimated risk. In addition, it is necessary to be able to capture the impact of the proposed change on the elements of the PRA. Subsection III.2.2.1 of this SRP section discusses the characterization of the proposed change in terms of PRA model elements. The results of this determination of the cause-effect relationships between the proposed application and the PRA models will help define the scope and level of detail required for the PRA to support the application. Subsections III.2.2.2 and III.2.2.3 of this SRP section discuss these topics. Many applications, such as those involving changes in component test intervals, allow explicit PRA modeling of the impact of the proposed change and quantification of the expected change in risk using plausible models of the impact on SSC unavailability to the extent that the affected components are included in the plant’s PRA. For other risk-informed applications, however, it may not be feasible to explicitly model the cause-and-effect relationship because the resulting actual impact on component unavailability is not clearly understood. For such applications, the use of risk categorization techniques provides a useful way to identify groups of SSCs that are less risk-important to risk and, as such, are possible candidates for a graded approach to regulatory requirements. Using such a categorization approach, however, it is still necessary to understand the potential or bounding impact of the proposed change and to assess the risk impact through appropriate sensitivity studies. In either the detailed quantification approach or the risk categorization approach, risk results should be derived from analyses of appropriate quality. Subsection III.2.2.4 and Appendix A to this SRP section present guidelines to help reviewers evaluate PRA quality as a function of the application. Finally, Appendix C to this SRP section discusses review issues related to the determination of risk contribution and component