Document: NUREG-0800
Document ID: 4f0d611c-d3fb-43e5-ab91-e7f7b4de3511
Document Type: srp
Title: Determining the Technical Adequacy of Probabilistic Risk
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0406/ML040630300.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.1
CFR Part: 
CFR Title: 

Content:
1) the PRA model, or the parts of the model required to support the application, represent the as-built and as-operated plant, which in turn implies that the PRA is up to date and reflects the current design and operating practices, (2) the PRA logic model has been developed in a manner consistent with industry practice and it correctly reflects the dependencies of systems on one another and on operator actions, and (3) the probabilities and frequencies are estimated consistently with the definitions of the corresponding events of the logic model. Second, the engineering analyses, assumptions, and approximations used in developing the PRA model must be appropriate and must demonstrate the robustness of the conclusions with respect to the uncertainties in the analysis. 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. 6 This is recognized in the application-specific regulatory guides such as Regulatory Guide 1.174, which give guidance on how to address the uncertainties by, for instance, performing appropriate sensitivity analyses. This aspect is expected to be addressed in the application-specific regulatory guides and associated SRP chapters. III.2.1 Determination That the PRA Model Is Current When using risk insights based on a PRA model, the PRA model must be up to date and represent the current plant configuration and operating practices. The reviewer should confirm that the licensee has a process for updating and maintaining the PRA model that is consistent with the staff position on the process in the ASME PRA standard. The reviewer should confirm that the PRA has been revised to reflect any significant changes in design or operational practices (including operating procedures), and