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:
gn criteria. The proposed licensing basis change should not affect meeting the intent of the plant’s design criteria referenced in the licensing basis. The evaluation of the proposed licensing basis change should demonstrate that the change does not significantly compromise meeting the intent of the plant’s design criteria thereby significantly reducing the effectiveness of one or more layers of defense. To evaluate this factor, the licensee should consider the current licensing basis of the plant and determine how the proposed licensing basis change would meet the intent of the plant’s design criteria and, for plants licensed under 10 CFR Part 52, meet the intent of the severe accident design features. In doing so, the licensee should demonstrate a full understanding of any impacts that the proposed licensing basis change might have on the design criteria or severe accident design features of the plant. It is recognized that, in general, the consideration of applicable regulations under the first principle of risk- informed regulation might fully address this defense-in-depth evaluation factor. Also, it is not the intent of this factor that changes to the plant’s design criteria or severe accident design features cannot be requested. For some hazards and for some licensees, defense-in-depth might be defined in the plant’s licensing basis. For example, the fire protection program for licensed nuclear power plants requires that fire protection defense-in-depth, which is scenario-based, be maintained. Any proposed licensing basis change should be evaluated against any plant-specific licensing basis defense-in-depth requirements in addition to the guidance presented herein. In addition, for plants licensed under 10 CFR Part 52, this factor should also address 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