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:
significance of SSCs that support operator actions for emergency and severe accident management. Such systems can include environmental controls, lighting, alarms, communications, and annuncia- tors. Determination of the categorization of such systems should include consideration of whether the loss of such systems could cause short-term or long-term problems, whether a system failure coincident with an accident is likely, and whether personnel could reasonably compensate for the loss of these support systems. 2.1.3 Identification of Components that Support Functions QA controls are applied at the component level while PRA basic events often represent groups of components. For example, a diesel failure basic event in the PRA can represent a large number of plant equipment parts, including such items as the diesel motor, oil pump, oil cooling fan, motor generator. Other components are not included in PRA basic events because their reliability is assumed to be high enough that their failure probability would have a negligible impact on the CDF and LERF. Therefore, 0 1.176-10 once the high safety-significant functions in a system for which GQA is being implemented have been identified, the plant equipment required to support the high safety-significant functions must be identified independently of the PRA basic event definitions. An efficient format to identify this component versus system function is a matrix that lists and cross- references the high safety-significant system functions to all the components needed to support each function at the level of equipment specificity at which changes in the application of QA controls will be pursued. Although a matrix is not necessary, well-organized information to support the final deliberations and to provide a traceable record for future licensee evaluations and for NRC inspections should cover all high safety-significant system functions, all system components that support the high safety-significant functions, and all