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:
ons for SSCs that are explicitly shown to play no role in SRP 19-B5 unanalyzed modes, it is more difficult to accept reductions for components that do play a role in unanalyzed (e.g., shutdown) modes. For such instances, conservative methods will be considered prudent. To address instances in which a PRA model exists but is considered misleading, caution is indicated. An example would be to down-classify SSCs from a PRA result (i.e., state that a high risk contributor is actually a low contributor), on the basis of panel judgment. It is not acceptable to place on the record both a PRA and a finding that clearly contradicts it. Although the panel is not expected to take the PRA as absolute truth, the test should be whether the record establishes a clear basis for a finding. A technical argument that begins with the misleading PRA result and furnishes supplementary information sufficient to justify a relatively minor change to a PRA result, or a qualified interpretation of a PRA result, is satisfactory. A cursory technical argument leading to a conclusion that qualitatively contradicts a major PRA result is an unsatisfactory record. c. Evaluation Findings The following language (or language equivalent to this) should appear in the safety evaluation report (SER), or exceptions should be noted and explained: • The integrated decisionmaking process is appropriate. Appropriate information was available, suitable issues were raised, the disposition of these issues was systematic and defensible, and the documentation of the findings is traceable and reviewable in principle, so that the basis for conclusions and recommendations is available for scrutiny and review. • The evaluation of risk significance represents appropriate consideration of probabilistic information, traditional engineering evaluations, sensitivity studies, operational experience, engineering judgment, and current regulatory requirements. • The technical information basis was adequate for the scope of