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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d, broadening the scope of review for technical adequacy. The reviewer, in applying this SRP section, should become familiar with those parts of the PRA identified as supporting the PRA results. III.2 Assessment of the PRA The reviewer should ensure that the parts of the PRA used for the application are of sufficient technical adequacy. The PRA should be technically sound. This means that (1) the PRA model, or the parts of the model relied upon to support the application, represent the as-built and as-operated2 plant, which in turn means that the PRA is up-to-date and reflects the current design and operating practices, (2) the PRA model is developed based on acceptable methods and data, and (3) the probabilities and frequencies are estimated consistent with the definitions of the corresponding events of the logic model. The engineering analyses, assumptions, and approximations used in developing the PRA model should be appropriate and demonstrate the robustness of the conclusions with respect to the uncertainties in the assessment. There are issues for which there is no consensus on analytical models or methods of analysis. Furthermore, PRAs are models, and in that sense the developers of those models rely on certain approximations to make the models manageable and on certain assumptions to address the uncertainties concerning the modeling of certain issues. This is recognized in RGs such as RG 1.174, which gives guidance on how to address the uncertainties by, for instance, performing appropriate sensitivity analyses. This aspect is expected to be addressed in the RGs and associated SRP sections that are applicable to a particular application. III.2.1 Determination that the PRA Model is Current When using risk insights based on a PRA model, the PRA model should reasonably represent the as-built and as-operated plant. “Reasonableness” is judged relative to the application being considered. For NFPA 805 applications, 10 CFR 50.48(c), which incorporates NFPA 805