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:
ility of engineered safety features. To evaluate this factor, the licensee should first determine whether the proposed licensing basis change necessitates compensatory measures. If not, this should be stated as the reason this factor is met. If compensatory measures are needed to support the proposed licensing basis change, the licensee should determine the extent to which programmatic activities, as compared to design features, are being relied upon. The intent of this factor is not to preclude the use of programs as compensatory measures but to ensure that reliance on programmatic activities as compensatory measures for a reduction in the capability of a design feature is not excessive. A proposed licensing basis change that does not affect how safety functions are performed or reduce the reliability or availability of the SSCs that perform those functions would meet this defense-in-depth factor. However, a licensee could contemplate a change where a reduction in the capability of those SSCs is compensated in some manner by reliance on plant programs (i.e., programmatic activities). In such a case, the licensee should assess whether the proposed licensing basis change would increase the need for programmatic activities to compensate for the lack of engineered features. If the proposed licensing basis change requires reliance on new programmatic activities or additional reliance on existing programmatic activities as a substitute for reliance on a design feature, the licensee should justify that the proposed reliance on the programmatic activities in place of design features is not excessive. Reliance on a programmatic activity as a compensatory measure might be considered excessive when a program is substituted for an engineered means of performing a safety function or when the failure of the programmatic activity could prevent an engineered safety feature from performing its intended function. The NRC also recognizes that compensatory measures are sometimes