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:
vided a qualification to resolve the concern. ASME/ANS RA-S-1.4-2021 includes the following risk assessment technical requirements: • Plant Operating State Analysis • Initiating Event Analysis • Event Sequence Analysis • Success Criteria Development • Systems Analysis • Human Reliability Analysis • Data Analysis • Internal Flood PRA • Internal Fire PRA • Seismic PRA • Hazards Screening Analysis • High Wind PRA • External Flooding • Other Hazards PRA • Event Sequence Quantification 1 Because the PRA consensus standards use the terms “requirement,” “require,” and other similar mandatory language, the staff’s endorsement, including staff exceptions, mirrors this language. However, the use of this language in this RG does not imply that this RG imposes any regulatory requirement or suggest that these standards are the only way to meet the statutory and regulatory requirements. RG 1.247, Appendix A, Page A-2 • Mechanistic Source Term Analysis • Radiological Consequence Analysis • Risk Integration The NRC understands that the nonmandatory appendices (NMAs) provided in ASME/ANS RA- S-1.4-2021 are not requirements. Rather, based on discussions with the JCNRM, the NRC understands that the JCNRM’s underlying purpose for providing the NMA notes and commentary was to help ensure that PRA analysts are apprised of certain known characteristics, challenges, and issues associated with the NLWR PRA model. While some of the discussion includes “primer-like” information, the language should not be viewed as prescriptive. The analyst should not interpret NMAs as limiting flexibility in the conduct of the technical analyses, or in the application of expert and engineering judgement. A broad range of tools, techniques, implicit/explicit analysis, and judgement may be required to address the diverse modeling required. With respect to the NMAs that provide notes on specific supporting requirements (SRs), the NRC understands that the