Document: NUREG-0800
Document ID: ac43f632-9db1-4857-9f56-bfba45965456
Document Type: srp
Title: * These are modifications to a plant’s design, operations, or other activities that require NRC approval. These modifica
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0232/ML023250195.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19
CFR Part: 
CFR Title: 

Content:
increase in risk with nonquantifiable but expected improvements in safety. In addition, the reviewer should ensure that the scope of the proposed changes is commensurate with, and fully supported by, the results of the analyses. That is, the scope of the change should be dependent on the degree of completeness of, level of detail of, and confidence in, the analyses. As an example, if the application concerned changing the treatment of SSCs according to their safety significance, a more detailed PRA model would allow a more detailed categorization into high or low significance than would a less detailed PRA model. Consequently, it would be expected that more SSCs could be characterized as low safety significant in the former case than the latter. It should be noted that both PRAs in this example may be stated to have sufficient quality for supporting the results as they were used in the decision. In this sense, quality can be thought of as a measure of the confidence in the results. SRP 19-25 To ensure that the important assumptions used in the engineering analysis to justify the LB change remain valid, the integrated decisionmaking process should ensure that the licensee maintains an appropriate set of programmatic activities (e.g., IST, QA, ISI, maintenance, monitoring) for important elements of the plant response capability. In addition, performance of compensating SSCs should be ensured (through programmatic activities) when these SSCs are used to help justify the relaxation of requirements for other SSCs. The process used by licensees to integrate traditional and probabilistic engineering evaluations for risk-informed decisionmaking is expected to be well-defined, systematic, and scrutable. Appendix B to this SRP chapter presents review guidance and staff expectations for the licensee’s integrated decisionmaking process. In evaluating the acceptability of a proposed change, reviewers should also address the following factors: • The cumulative impact of