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:
letion time changes are accompanied by implementation of a configuration risk management program, which requires licensees to examine their plant configuration before voluntarily entering the approved condition. Section C.2.4 of this guide indicates that the application would be given increased NRC management attention when the calculated values of the changes in the risk metrics, and their base values, when appropriate, approach the acceptance guidelines. Therefore, if the risk metrics approach or even slightly exceed the acceptance guidelines, the licensee’s submittal should address the following issues: • an identification of the significant contributors to the risk metrics and assessment of the realism with which they have been evaluated, which is particularly important if some contributors are known to have been assessed conservatively or non-conservatively. • the cumulative impact of previous changes and the trend in CDF (the licensee’s risk management approach), • the cumulative impact of previous changes and the trend in LERF (the licensee’s risk management approach), • the impact of the proposed change on operational complexity, burden on the operating staff, and overall safety practices, • plant-specific performance and other factors (for example, siting factors, inspection findings, performance indicators, and operational events), and Level 3 PRA information, if available, • the benefit of the change in relation to its CDF/LERF increase, • the practicality of accomplishing the change with a smaller CDF/LERF impact, and • the practicality of reducing CDF/LERF when there is reason to believe that the base CDF/LERF are above the guideline values (i.e., 10-4 and 10-5 per reactor year, respectively). 3. Element 3: Define Implementation and Monitoring Program Careful consideration should be given to implementation of the proposed change and the associated performance-monitoring strategies. The primary goal of Element 3 is to ensure that no