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
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Content:
is lacking, reviewers should either request additional licensee justification or seek independent analysis. Licensee justification could include the use of alternative plausible models to justify the conclusions (thus addressing the model uncertainty) or the redesign of the change such that the change is not affected by the choice of success criteria. Some mission success criteria can validly be extrapolated between similar plants when a firm basis for the criteria is created at the first plant and when the licensee shows that plant-specific features do not invalidate the comparison. On an application-specific basis, reviewers should determine whether the definition of the system success criteria will be affected by the application-specific elements or by the elements in the same minimal cutset or accident scenario as the application-specific element. Reviewers should ensure that the success criteria are not so optimistic that they underestimate the required number of components (i.e., overestimate the size of the minimal cutset). c. Evaluation Findings In cases where conclusions are sensitive to the mission success criteria, the reviewers should verify that information provided and review activities conducted support findings equivalent to the following: A technical basis has been established for the mission success criteria used in the analysis. Analytical elements of the technical basis have received an appropriate level of configuration control and quality assurance. Where comparison with analogous criteria from other plants is possible, this comparison has been justified. A.6 Use of Appropriate Data a. Areas of Review In risk-informed applications, it is important that the licensee use appropriate SSC failure data. While plant-specific data is preferred, for plants with little operating history the only choice might be the use of generic data. Furthermore, when the impact of the change is being modeled as a modification of parameter values, sufficient