Document: NUREG-0800
Document ID: e32f0820-4e33-476e-aa36-4ca8c2c64af0
Document Type: srp
Title: Use of Probabilistic Risk Assessment in Plant-Specific, Risk-Informed Decisionmaking:
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0119/ML011940192.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.0
CFR Part: 
CFR Title: 

Content:
articularly controversial, reviewers should evaluate the relevant success criteria and the basis for each. If the basis is analytical, ii: may be appropriate to evaluate of the code and the input data used. When it is determined that the computer codes used have not received adequate licensee or other industry review, closer examination of the models should also be considered. SRP 19-Al 0 The models, codes, and inputs used to determine mission success criteria should meet QA standards that are consistent with generally accepted methods. Standards should include configuration control of the analysis inputs and results. The standards do not have to be the same as the standards applicable to SAR analysis, but they should be explicit (i.e., engineering calculations and codes should be verified and quality assured) and they should be formalized as part of the licensee's QA program. In cases where the basis for the success criteria 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.