Document: NRC Regulatory Guide
Document ID: 47b09be1-4bf8-45f9-a099-7fed871c09bd
Document Type: regulatory_guide
Title: Plant-Specific, Risk-Informed Decisionmaking: Inservice Testing (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2114/ML21140A055.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.175
CFR Part: 
CFR Title: 

Content:
Finality, and Information Requests,” Washington, DC. Appendix A to RG 1.175, Page A-1 APPENDIX A DETAILED GUIDANCE FOR INTEGRATED DECISIONMAKING A-1. Introduction The increased use of probabilistic risk assessment (PRA) in nuclear plant activities, such as in risk-informed (RI)-inservice testing (IST) programs, will require a balanced use of the probabilistic information with the more deterministic engineering information. Some structured process for considering both types of information and making decisions will be needed that will allow improvements to be made in plant effectiveness while maintaining adequate safety levels. This will be particularly important during initial program implementation and also for the subsequent early phases of the program. In some instances, the physical data from the PRA and from the deterministic evaluations may be insufficient to make a clear-cut decision. At times, these two forms of information may even seem to conflict. In such cases, the licensee should assemble the appropriate skilled staff to consider all the available information in its various forms and to supplement this information with engineering judgment to determine the best course of action. The participants involved in this important role have generally been referred to in various industry documents as an “expert panel.” A-2. Basic Categories of Information to be Considered Risk-importance measures may be used together with other available information to determine the relative risk ranking (and thus categorization) of the components included in the evaluation. Results from all these sources are then reviewed before making final decisions about where to focus IST resources. Although the risk ranking of components can be used primarily as the basis for prioritizing IST at a plant, additional considerations need to be addressed (e.g., defense-in-depth, common cause, and the single-failure criterion), which may be more constraining than the risk-based criteria in