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:
is revision include expanding the discussions on uncertainties, including aggregation of risk results, consistent with NUREG-1855, “Guidance on the Treatment of Uncertainties Associated with PRAs in Risk-Informed Decisionmaking” (Ref. 7), updating the risk acceptance guideline figures, and incorporating discussions related to application of this guide to new reactors. Background The Commission directed the staff in the Staff Requirements Memorandum (SRM) on SECY-11- 0014, “Staff Requirements – SECY-11-0014 – Use of Containment Accident Pressure in Analyzing Emergency Core Cooling System and Containment Heat Removal System Pump Performance in Postulated Accidents” (Ref. 8), and the SRM on SECY-15-0168, “Staff Requirements – SECY-15-0168 – Recommendations on Issues Related to Implementation of a Risk Management Regulatory Framework” (Ref. 9), to revise the defense-in-depth guidance using precise language to assure the defense-in-depth philosophy is interpreted and implemented consistently. Both the NRC and the nuclear industry recognize that PRA has evolved to the point that it can be used increasingly as a tool in regulatory decisionmaking. In August 1995, the NRC issued a final Commission policy statement on the use of PRA methods in nuclear regulatory activities titled, “Use of Probabilistic Risk Assessment Methods in Nuclear Activities: Final Policy Statement” (Ref. 10), which adopted the following policy: • The use of PRA technology should be increased in all regulatory matters to the extent supported by the state-of-the-art in PRA methods and data and in a manner that complements the NRC’s deterministic approach and supports the NRC’s traditional defense-in-depth philosophy. • PRA and associated analyses (e.g., sensitivity studies, uncertainty analyses, and importance measures) should be used in regulatory matters, where practical within the bounds of the state-of-the-art, to reduce unnecessary conservatism associated with current