Document: NRC Regulatory Guide
Document ID: 8a2332d3-66ca-40af-84e1-507db8b26559
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:
orsement. As part of an application, an applicant or licensee should describe the measures it has taken to ensure that the design-specific or plant-specific PRA is acceptable for its intended use. The measures may include items such as any self-assessments and peer reviews against the ASME/ANS NLWR PRA standard, as well as any actions taken to address self-assessment and peer review results. When performed prior to the application, the peer review provides findings and observations on PRA completeness and acceptability, including consideration of the scope, level of detail, conformance to a consensus PRA standard, plant representation of the PRA model, the assumptions made in the RG 1.247, Page 57 development of the results, and the uncertainties that impact the analysis. If a peer review has not been performed and the applicant’s justification fails to give the staff adequate confidence in the PRA models, results, and insights, then an in-depth staff review is warranted. An in-depth staff review will assess the applicant’s PRA against the PRA elements and the staff positions described in this RG to determine the PRA’s acceptability. Because key assumptions, logic modeling, and modeling parameters can significantly impact the PRA results and insights, staff review of their acceptability is necessary to ensure that the PRA yields reasonable and acceptable information that can be relied on when making risk- informed regulatory decisions. In general, an acceptable peer review process should identify the necessary steps to compare the PRA against established requirements and criteria (e.g., technical requirements defined in the NLWR PRA standard). As part of this process, the PRA models are compared against the plant design and procedures, if available, to validate that the models reflect the as-designed, as-to-be-built, as-to-be-operated plant, or the as-built and as-operated plant. Additionally, the peer reviewers perform independent walkdowns, if possible, to