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:
cific point in time (see Section C.2.3 of this RG for additional information on the relationship between RG 1.174 and the ASME/ANS standard). Acceptability of the engineering analyses is determined by assessing the scope, level of detail, supporting technical analyses, and plant representation. • The plant-specific PRA supporting the licensee’s proposals has been demonstrated to be acceptable. • Appropriate consideration of uncertainty is given in the analyses and interpretation of findings, including use of a program of monitoring, feedback, and corrective action to DG-1285, Page 9 address key sources of uncertainty. NUREG-1855 provides acceptable guidance for the treatment of uncertainties in risk-informed decisionmaking. • The use of CDF and LERF as bases for PRA acceptance guidelines is an acceptable approach to address Principle 4. Use of the Commission’s Safety Goal QHOs in lieu of CDF and LERF is acceptable in principle, and licensees may propose their use. However, in practice, implementing such an approach would require an extension to a Level 3 PRA, in which case the methods and assumptions used in the Level 3 analysis, and associated uncertainties, would require additional attention. Guidance on risk metrics for plants licensed under 10 CFR Part 52 is provided later in this section. • Increases in CDF and LERF resulting from proposed licensing basis changes should be limited to small increments. The cumulative effect of such changes, both risk increase and risk decrease (if available), should be tracked and considered in the decision process. For purposes of this guide, a proposed licensing basis change that meets the acceptance guidelines discussed in Section C.2.2.4 of this RG is considered to have met the intent of the policy statement. • The acceptability of proposed licensing basis changes should be evaluated by the licensee in an integrated fashion that ensures that all principles are met. • Data, methods, and assessment criteria