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:
ufficient safety margins are maintained. An acceptable set of guidelines for making that assessment is summarized below. Other equivalent decision guidelines are acceptable. • Codes and standards or alternatives approved for use by the NRC are met. " Safety analysis acceptance criteria in the licensing basis (e.g., Final Safety Analysis Report (FSAR) and supporting analyses) are met, or proposed revisions provide sufficient margin to account for analysis and data uncertainty. 2.2.2 Guidelines for Defense in Depth and Safety Margins Defense in depth and safety margins are expected to be addressed generally by considering the following GQA program aspects. * The GQA process will not result in changes to the plant configuration. Therefore, no existing plant barriers will be removed. Additionally, existing system redundancy, diversity, and independence will be maintained. " The GQA process will not result in changes to the technical requirements (e.g., design bases or operational parameters) associated with SSCs. " The resulting QA provisions will provide the necessary level of assurance that low safety- significant, safety-related and high safety- significant, non-safety-related SSCs remain capable of performing their safety function. The core damage frequency (CDF) and large early release frequency (LERF) figures of merit do not fully cover long-term containment overpressure protection. Functions credited in the PRA for long-term overpressure protection, but which do not contain any SSCs with CDF or LERF based importance measures above the guideline values, should be identified and the safety significance explicitly assigned. For example, the containment spray systems for PWRs may not contribute to the prevention or mitigation of core damage or large early release. An important factor to ensure that defense-in- depth and safety margin considerations are not degraded during the implementation of GQA is control of potential common mode failures. As discussed in