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:
ting modes and perform a variety of functions, with each function a well-defined task requiring the proper operation of some subset of system equipment. Although certain QA controls are applied at the component or even piece-part level, safety-significance categorization is most appropriately defined at the system function level. Therefore, the guidance in this regulatory guide is based on determining the safety-significance of system functions, identifying the components and component operational modes required to support high safety-significant functions, and determining the categorization of the components based on this information. The categorization process must also be capable of systematically tracking and documenting system functional boundaries, defined as the point (compo- nent) at which a system operating in a particular mode functionally interfaces with a connected system. The categorization of the safety significance of support functions is generally determined by the categorization of the function being supported, augmented by a quantitative or qualitative evaluation of the support system's aggregate safety significance. Interfacing function categorization should be well documented, traceable, and internally consistent. Licensees who chose to implement GQA programs one system at a time must ensure that support system interfaces are sufficiently well defined and documented that the safety significance of interfacing systems will always be explicitly considered as each system is evaluated. The scope, level of detail, and quality required of the PRA are commensurate with the application for which it is used and commensurate with the role the PRA results play in the integrated decision process. PRAs used to support a GQA application should realistically reflect 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