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:
by using a bounding or demonstrably conservative analysis with defined quantitative screening criteria to demonstrate that the risk from some external events is sufficiently low to eliminate them from additional consideration. Walkdowns of the plant site and plant buildings are used to confirm the assumptions used for the screening basis. For some risk-informed applications, the validity of the assumptions used to screen out a hazard from the base PRA may need to be examined and confirmed by the staff, based on related application-specific guidance. Table 7 summarizes the characteristics and attributes needed for the technical elements for screening and conservative analysis. Table 7. Summary of Technical Characteristics and Attributes of Screening and Conservative Analysis of Hazards Element Technical Characteristics and Attributes Screening and Conservative Analysis • All potential hazards that can affect the site identified. • Preliminary screening performed using a defined set of criteria. • Bounding or conservative analysis performed using defined quantitative screening criteria. • Basis for screening confirmed with walkdown. Technical Elements for High Wind, At-Power PRA This section identifies the technical elements for a high wind, at-power PRA. The objective for each technical element is briefly described and the characteristics and attributes needed to achieve the objective are provided in Table 8. The technical elements for a high wind, at-power PRA are: • high wind hazards analysis • high wind fragility analysis • high wind plant response analysis DG-1362, Page 28 Screening methods can often be used to show that the contribution of high winds to CDF and/or LERF/LRF is insignificant. The considerations in this section apply to those high wind phenomena that have not been screened out. The types of high wind events that should be considered in the analysis are site dependent. These can include tornados and their effects, cyclones, hurricanes,