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:
in terms of both scope and how well the risk and the change in risk is assessed. Conversely, emphasis on the various aspects of the PRA can be reduced if a proposed change to the LB results in a risk decrease or a change that is very small, or if the decision could be based mostly on traditional engineering arguments, or if compensating measures are proposed such that it can be convincingly argued that the change is very small. A PRA used in risk-informed regulation should be performed correctly, in a manner that is consistent with accepted practices. RG 1.200 describes one acceptable approach for determining whether the acceptability of the base PRA, in total or the parts that are used to support an application, is sufficient to provide confidence in the results, such that the PRA can be used in regulatory decisionmaking for light-water reactors. Specifically, RG 1.200 provides guidance for the following: • an acceptable PRA • the NRC’s position on PRA consensus standards and industry PRA peer review program documents, • demonstration that the baseline PRA (in total or specific parts) used in regulatory applications is acceptable, and • documentation of the acceptability of the PRA to support a regulatory submittal. Other approaches may also be acceptable, but may increase the scope of the staff review or result in a lower priority based on the availability of staff resources. RG 1.200 endorses an ASME/ANS standard that addresses the base PRA for CDF and LERF for internal and external hazard groups at-power. Other standards for low power and shutdown modes of operation and Level 2 PRAs, for example, are under development. This RG is intended for a variety of applications, consequently the scope, level of detail, conformance with the technical elements, and plant representation may vary. The PRA should realistically reflect the actual design, construction, operational practices, and operational experience of the plant and its owner. This should include