Document: NRC Regulatory Guide
Document ID: cde52d5a-adf9-49be-9d1f-59449dfca895
Document Type: regulatory_guide
Title: TRIAL - Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2123/ML21235A008.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.247
CFR Part: 
CFR Title: 

Content:
nt. The current state-of-practice in PRA technology reflects that there are issues where there is no consensus on the method of analysis. However, in the context of risk-informed regulatory decisions, a method or model approach that the NRC has used or accepted for the application is considered to be a consensus method or consensus model. A consensus method or model may have a publicly available, published basis and may have been peer reviewed and widely adopted by an appropriate stakeholder group. Assurance that the PRA and its results used to support an application have been developed and used in a technically correct manner indicates that (1) the PRA model supporting the application represents the as-designed, as-to-be-built, or as-to-be-operated plant or the as-built and as-operated plant. This assurance 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 and it correctly reflects the dependencies among 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 and based on the best information available. The applicant or holder of a license, certification, or permit should demonstrate that the PRA model represents the as-designed, as-to-be-built, and as-to-be-operated plant or the as-built and as-operated plant, as dictated by the application. Demonstrating this can be achieved through (1) the establishment of a PRA configuration control process that includes provisions for updating the model periodically to reflect changes that impact the significant event sequences, and (2) using a national consensus standard, as endorsed by the NRC. Additionally, PRA self-assessments and peer reviews that follow an approved process should be used, as endorsed by the NRC, to demonstrate how the PRA