Document: NRC Regulatory Guide
Document ID: 82659041-98b0-4721-b25d-c4fb2ea394d0
Document Type: regulatory_guide
Title: An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions on Plant-Specific Changes to the Licensing Basis (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1635/ML16358A153.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.174
CFR Part: 
CFR Title: 

Content:
ess those design features for the prevention and mitigation of severe accidents that are described and analyzed in accordance with 10 CFR 52.47(a)(23) and 10 CFR 52.79(a)(38). Section DG-1285, Page 23 C.I.19.8 of RG 1.206, “Combined License Applications for Nuclear Power Plants (LWR Edition)” (Ref. 29), provides guidance on implementing these requirements and ties the requirements to the issues and performance goals identified in SECY-90-016 and SECY-93-087, which the Commission approved in their respective SRMs on SECY-90- 016 and SECY-93-087. Also, RG 1.216, “Containment Structural Integrity Evaluation for Internal Pressure Loadings above Design-Basis Pressure” (Ref. 30), provides acceptable methods for an analysis that specifically addresses the issues and performance goals identified in SECY- 90-016 and SECY-93-087 and related SRMs on containment structures in nuclear power plants under severe accident conditions. For this factor, the potential impacts on these severe accident design features should also be evaluated to ensure the intent of these design features continue to be met. Integrated Evaluation of the Defense-in-Depth Evaluation Factors The guidance for evaluation of the seven factors described above should enable the licensee to demonstrate the impact of a proposed licensing basis change on defense-in-depth. The licensee should be able to conclude whether the change maintains consistency of the plant design with the defense-in-depth philosophy by showing that the intent of each factor is still met following the implementation of the proposed licensing basis change. The evaluation should demonstrate the licensee’s understanding of how the change impacts plant design and operation both from risk and traditional engineering perspectives. 2.1.2 Safety Margin The engineering evaluation should assess whether the impact of the proposed licensing basis change is consistent with the principle that sufficient safety margins are maintained. Here also,