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:
At-Power Operating Mode Index No Issue Position Resolution estimates should be conservative. Ensuring the fragility estimate is conservative may require the development of a more realistic estimate to compare against, which arguably makes the CC I requirement more of a CC II requirement and effectively defeats the purpose of establishing a CC I requirement. Therefore, besides the action verb, the main distinction between CC I and CC II should be the “refinement” of fragilities (conservative or bounding for CC I and realistic for CC II). fragilities for the failure modes of interest identified in SFR-E2 using plant-specific data, and ENSURE that they are realistic. or JUSTIFY (e.g., through the calculation of seismic CDF and LERF per HLR-SPR- E) the use of generic fragility data (e.g., fragility test data, generic seismic qualification test data, and earthquake experience data) or conservative assumptions for the SSCs as being conservative appropriate for the plant and not significant to the overall results. SFR-E3 For CC II: calculated seismic fragility should be realistic. The requirement to ensure is unnecessary as this effectively a function of a peer review. The addition of showing no difference in insights or masking of risk helps ensure the use of generic fragility or conservative assumptions is acceptable at CC II. Qualification CALCULATE realistic seismic fragilities for the failure modes of interest identified in SFR-E2 using plant-specific data, and ENSURE that they are realistic. or JUSTIFY (e.g., through the calculation of seismic CDF and LERF per HLR-SPR-E) the use of generic fragility data (e.g., fragility test data, generic seismic qualification test data, and earthquake experience data) or conservative assumptions for any SSCs by showing no differences in insights or masking of risk as being appropriate for the plant. SFR-E4 -------------------- No objection -------------------- SFR-E5 The SR (CC I and II) refers to SPR-B6 for identification