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:
and should be modeled in detail using a PRA. This latter type of hazard is commonly referred to as an “other hazard,” and Regulatory Position C.1.3.14 provides additional guidance on modeling such hazards. A list of hazards and their potential impacts that should be considered include, but may not be limited to, those items listed in Tables B-1 and B-2. Table B-1 provides a list of hazards consistent with those in Table HS-2 of the American Society of Mechanical Engineers (ASME)/American Nuclear Society (ANS) advanced nonlight-water reactor PRA standard, ASME/ANS RA-S-1.4-2021, “Probabilistic Risk Assessment Standard for Advanced Non-Light Water Reactor Nuclear Power Plants” (Ref. 1). Table B-1 also provides a general description of direct and indirect impacts of each hazard within a hazard group that should be considered during the development of a PRA. The genesis of this list of hazards can be traced back to NUREG/CR-2300, “PRA Procedures Guide: A Guide to the Performance of Probabilistic Risk Assessments for Nuclear Power Plants,” issued January 1983 (Ref. 2), and earlier nuclear power plant PRA studies. This list of hazards has evolved and expanded over the past several decades based on insights and lessons learned from other PRA-related programs and applications such as licensees’ responses to Generic Letter 88-20, Supplement 4, “Individual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities—10 CFR 50.54(f),” dated June 28, 1991 (Ref. 3). Table B-2 lists hazard causes and potential conditions to consider during the process of determining what risk a given hazard poses to a facility. The taxonomy of these hazard groups and the hazards within those groups are relevant to applications only. RG 1.247, Appendix B, Page B-2 Table B-1. List of Hazards Hazard Hazard Group Direct or Secondary Impact of Hazard Animals Animals Land-based or airborne animals that cause damage to plant equipment, such as loss of offsite