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:
hods or techniques. Therefore, to ensure that the PRA represents the risk of the as-designed, as-to-be-built, or as-to-be-operated plant or the current as-built and as-operated plant, depending on the stage of the licensing process, the PRA is maintained and upgraded over time. COL holders should meet all applicable requirements in the ASME/ANS NLWR PRA standard, as endorsed in Appendix A to this RG, when the PRA is updated as required by 10 CFR 50.71(h)(2) and 10 CFR 50.71(h)(3). The characteristics and attributes of an acceptable process for maintaining and upgrading a PRA are as follows: • The process is capable of monitoring PRA inputs and the collection of new information affecting the PRA. • The cumulative impact of pending plant changes is considered. • The process includes maintaining the configuration control of computer codes used to support the PRA. • The process establishes when the PRA model should be updated based on new information or new models, techniques, and tools. • A peer review is performed after the PRA is upgraded. C.2 National Consensus Standards and Industry Programs for Probabilistic Risk Assessment One acceptable approach to demonstrate conformance with the regulatory positions in Section C of this RG is to use a national consensus PRA standard or standards, as endorsed by the NRC staff with exceptions, that address the scope of the PRA. ASME and ANS have issued the ASME/ANS NLWR PRA standard. This standard provides process and technical requirements for a PRA of an NLWR that addresses all radiological sources, all hazards, all POSs, and all levels of PRA analysis (i.e., from initiating event to radiological consequences). National consensus PRA standards establish requirements for what an acceptable PRA should include to satisfy the applicable regulations in 10 CFR Part 50 and 10 CFR Part 52. However, these PRA standards do not address how to meet the requirements for an acceptable PRA. Because the joint ASME and ANS national