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:
on the use of any NDMs. The ASME/ANS Level 1/LERF PRA standard provides requirements for (1) the establishment of a peer review process, and (2) PRA peer review team qualifications and documentation. A peer review methodology (i.e., process) is documented in the industry-developed peer review guidance documents. As stated earlier, the peer review is to be performed against established national consensus PRA standards (e.g., the ASME/ANS Level 1/LERF PRA standard, as endorsed by the NRC with exceptions and clarifications). If different criteria are used than those in established national consensus PRA standard, then it should be demonstrated that these different criteria are consistent with the established national consensus PRA standards endorsed by the NRC with exceptions and clarifications. A peer review may be performed on the base PRA model or on a PRA upgrade, which may involve use of an NDM, or in the form of an independent assessment reviewing the closure of findings from a peer review. The following sections provide guidance on each of these scenarios. Peer Review of a Base PRA Model The peer review process includes a documented procedure used to direct the peer review team’s evaluation of the acceptability of a base PRA. The review process compares the base PRA against established criteria (e.g., technical requirements defined in a national consensus PRA standard that conforms to the PRA characteristics and attributes such as those provided in regulatory position C.1.2). In addition to reviewing the methods used in the base PRA, the peer review determines whether the methods were applied correctly. The base PRA models are compared against the plant design and procedures to validate that they reflect the as-designed, or the as-built and as-operated plant. Independent walkdowns are performed to confirm PRA inputs, especially for external hazard PRAs. Assumptions are reviewed to determine if they are appropriate and to assess their impact on the base PRA