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:
Technical Requirements for Hazard Screening Analysis Index No. Issue Position Resolution in the pre-operational stages of the plant life cycle. These types of reviews should be performed for any stage of the plant life cycle. HS-B3 through HS-B4 ------------------------ No objection ---------------------------------- HS-B5 When assessing whether a hazard or hazard group cannot physically impact the plant or plant operations, it is necessary to consider a range of magnitudes and frequencies. Without such consideration, lower frequency events with a higher magnitude that might otherwise prove important to the risk results may be excluded. Additionally, the values in RI-A5 referenced in item (f) are presented as reporting values, not screening values. Using the reporting values as screening values could be too permissive in excluding contributors from the PRA as screening using a consequence criterion may not be effectively equivalent to screening using a frequency criterion. Additionally, this Qualification USE SCR-3 in Table 1.10-1 when qualitatively screening out a hazard or hazard group by showing that either: (a) the hazard or hazard group cannot physically impact the plant or plant operations (e.g., it cannot occur close enough to the plant to affect it), taking into account the range of magnitudes and frequencies of the hazard or hazard group; (b) the hazard or hazard group does not result in a plant trip (manual or automatic) or require a plant shutdown; (c) the hazard or hazard group is included in the definition of another hazard; (d) the hazard or hazard group could not result in worse effects to the plant as another hazard that has a significantly higher frequency; (e) the hazard or hazard group is slow in developing and there is demonstrably sufficient time to eliminate the source of the threat or to provide an adequate response; (f) the hazard or hazard group cannot produce a consequence above the value set in RI-A5. RG 1.247, Appendix A, Page A-51 Table