Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
igned or as-built and as- operated plant, which, in turn, indicates that the PRA reflects the current design and operating practices and experience, where appropriate; (2) the PRA logic model has been developed in a manner consistent with industry good practice (see the Glossary for this RG) and that it correctly reflects the dependencies amongst systems, components, and operator actions; and (3) the probabilities and frequencies used are estimated consistently with the definitions of the corresponding events in the PRA logic model. For the second aspect, the current state-of-practice in PRA technology is that there are issues for which there is no consensus on methods of analysis. Furthermore, PRAs are models that rely on certain approximations and judgements to make the models tractable and certain assumptions that address uncertainties related to modeling specific issues. Regulatory position C.3.3.2 of this RG, RG 1.174 and, in more detail, NUREG-1855 provides guidance on how to address and treat the uncertainties associated with a PRA. In accordance with that guidance, the impact of these assumptions and approximations on the results of interest to the application should be understood. Assessment that the PRA Model is Technically Correct When using risk insights based on a PRA model, the licensee or the applicant ensures that the PRA model, or at least those portions of it needed to provide the results, is technically correct as discussed above. The licensee is to demonstrate that the PRA model represents the current plant design and configuration and represents current operating practices and operating experience to the extent required to support the application. This demonstration can be achieved through a PRA configuration control plan that includes provisions for updating the model periodically to reflect changes that impact the significant accident sequences. The various national consensus PRA standards and industry documents that provide guidance on the