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:
failures of SSCs to determine whether licensee-established performance criteria or quality elements need to be changed. If the failure is determined to apply generically to other SSCs,-or the failure represents a potential common cause concern for similar equipment installed in multiple systems, or if an excessive number of failures occurs that exceed licensee-established thresholds, then further licensee evaluations are warranted. An apparent cause determination is warranted to screen the failures in order to ascertain the necessity to perform more in-depth evaluations. The SSC risk-categorization methodology could be affected by the SSC reliability and unavailability assumptions. These assumptions also could affect final categorization decisions to the extent that reliability and unavailability were used as a licensee criterion for determining the safety significance of an SSC that fails or exhibits a declining performance trend. Both the probabilistic and non-probabilistic methods previously used should be re-evaluated when there is significant disparity between the analysis assumptions and the observed data. The GQA 1.176-18 program controls should be evaluated to determine whether they need to be strengthened as a result of the failures. Based upon positive performance monitoring results, the licensee may further evaluate both safety- significance categorization and assignment of QA controls to identify situations in which they may be further relaxed. Such changes would be evaluated and reviewed by the staff as necessary, as discussed in other sections of this guide. When a safety-related SSC has been categorized as low safety significant and, because of events such as plant modifications, reanalysis, or human errors, it is determined that the SSC should now be categorized as high safety significant, the licensee should take appropriate corrective action and evaluate the acceptability of the GQA controls applied to the SSC while categorized as low safety