Document: NRC Regulatory Guide
Document ID: a5ee4c78-1135-4bb6-8d54-e974a3402f87
Document Type: regulatory_guide
Title: An Approach for Plant-Specific, Risk-Informed Decisionmaking: Graded Quality Assurance
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1221/ML12216A017.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.176
CFR Part: 
CFR Title: 

Content:
ct the actual design, construction, operational practices, and operational experience of the plant and its operator. Furthermore, all calculations using the PRA model should be performed correctly and in a manner that is consistent with accepted practices. The licensee must demonstrate that the PRA and the calculations are of sufficient quality to support a decision on the acceptability of the proposed change. A well organized and documented safety- significance categorization process, sensitivity and bounding studies performed with the PRA, and implementation of a robust monitoring and feedback program can provide reasonable assurance that implementation of GQA should result in an insignificant change in risk. Consequently, NRC staff evaluation of the quality of the PRA may be directed toward a finding that the quality is sufficient for assigning SSCs into broad safety-significant catego- ries for consideration in an integrated decisionmaking process. All operational modes and internal and external events should be included in the evaluation of the safety significance of systems, functions, and components. PRA models and results for core damage and large early release frequency for internal initiating events at full power should be used to support the categorization process. Licensees may use qualitative studies of other initiating events and operational modes that identify and characterize scenarios that are believed to be important, but without expending significant resources in quantifying the frequencies of 1.176-7 the scenarios. Seismic margin analysis and fire- induced vulnerability evaluations (FIVE) done to support the individual plant examination of external events (IPEEE) analyses and shutdown risk configura- tion control evaluations are examples of qualitative studies that have been developed. Evaluations based on quantitative external and shutdown studies may also be used. If importance measures from quantitative studies are combined with measures