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 changes. This approach assesses the impact of the risk associated with the proposed changes in plant design and operation by considering engineering issues and applying risk insights. Plants should transition at or before their initial fuel load (e.g., following the 10 CFR 52.103(g) finding) from the use of the CDF, large release frequency, and conditional containment failure probability risk metrics and acceptance guidelines used in the design certification and combined license applications to the CDF and LERF risk metrics and acceptance guidelines for risk-informed applications used in this RG. More information can be found in the SRM on SECY-12-0081, “Staff Requirements – Secy-12-0081 – Risk-Informed Regulatory Framework for New Reactors” (Ref. 21). In addition, for plants licensed under 10 CFR Part 52, the deterministic containment performance metric should also be maintained. The designs certified by the NRC under 10 CFR Part 52 implement design features that are in addition to those required by 10 CFR Part 50, particularly features for severe accidents. The requirements for these design features were codified in the Appendixes to 10 CFR Part 52 for each certified design in a section titled “Applicable Regulations.” The certified designs include features to ensure containment performance. Plants licensed under 10 CFR Part 52 should ensure that the containment maintains its role as a reliable, leak-tight barrier for approximately 24 hours following the onset of core damage under the more likely severe accident challenges and, following this 24-hour period, the containment should continue to provide a barrier against the uncontrolled release of fission products. More information can be found in SECY-90-016, “Evolutionary Light-Water Reactor (LWR) Certification Issues and Their Relationship to Current Regulatory Requirements” (Ref. 22), and SECY- 93-087, “Policy, Technical, and Licensing issues Pertaining to Evolutionary and Advanced