Document: NUREG-0800
Document ID: f60cdc8f-3c25-45c3-a1d3-b0f530961625
Document Type: srp
Title: DETERMINING THE TECHNICAL ADEQUACY OF PROBABILISTIC RISK
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1219/ML12193A107.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.1
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levant documents as endorsed. The capability category needed for each PRA supporting requirement of the applicable PRA standard technical element is dependent on the application. In general, the staff anticipates that current good practice, i.e., Capability Category II of the ASME/ANS Standard, is the level of detail that is adequate for the majority of applications. However, for some applications, Capability Category I may be sufficient for some PRA supporting requirements, whereas for other applications it may be necessary to achieve Capability Category III for specific PRA supporting requirements. The reviewer should focus on the elements that have deviations from, or have discrepancies with, the PRA technical requirements of the endorsed documents. The reviewer should ensure that the deviation or discrepancy is acceptable as compared to the endorsed documents. The reviewer should also determine that the issues have been addressed adequately when the licensee provides reasons as to why the discrepancies are not important, or demonstrated that the discrepancy has no significant impact on the results used in the decision. III.2.3 Assessment of Engineering Analyses, Assumptions, and Approximations Since the standards and industry PRA programs are not (or are not expected to be) prescriptive, there is some freedom on how to model certain issues in the PRA. In dealing with this model uncertainty, different analysts may make different assumptions regarding these issues, yet the issues still meet the PRA standard or have been accepted by the peer review. The choice of a specific assumption or a particular approximation may, however, influence the results of the PRA. The staff should ensure that the conclusions drawn from the PRA are not invalidated by the use of specific assumptions. This is addressed primarily in the application-specific assessment through the use of sensitivity analyses. The staff should review the licensee’s basis for those assumptions and their