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
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CFR Title: 

Content:
the basis of an evaluation of the significance of the hypotheses associated with the modes that exceed the guidelines. • Completeness Uncertainty: Reviewers should determine whether the licensee has adequately addressed the limitations in the PRA scope and other completeness issues, either by limiting the scope of the application or by demonstrating that the impact of the unanalyzed portion of the risk on both the base case risk and on the change in risk is bounded or can be neglected. Section III.2.2.2 of this SRP chapter discusses this further. III.2.2.5.3 Cumulative and Synergistic Effects from all Applications In evaluating the licensee's submittal, reviewers should consider the effects of the proposed changes in light of previously submitted changes implemented by the licensee. Optimally, the PRA used for the current application should already model the effects of past applications. However, qualitative and synergistic effects are sometimes difficult to model in the PRA. Therefore, a review of changes in risk (both quantifiable and non-quantifiable) from previously submitted changes to the plant's design and operation would provide a means to account for the cumulative and synergistic effects of these changes. For all previous changes, reviewers should consider the following factors: • The calculated change in risk for each application (CDF and LERF) and the plant elements (SSCs, procedures, etc.) affected by each change, • Qualitative arguments used to justify the change (if any) and the plant elements affected by those arguments, SRP 19-23 • Compensatory measures or other commitments used to help justify the change (if any) and the plant elements affected, • A summary of the results from the monitoring programs (where applicable) and a discussion on how these results have been factored into the PRA or into the current application, • The plant risk profile to ensure that the accumulation of changes has not created dominant risk contributors. If the