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:
-IST program with respect to the changes in CDF and LERF, as discussed in Sections C.2.4 and C.2.5 of RG 1.174. In addition, the PRA can provide a baseline risk profile of the plant, and the extent of analysis of the baseline CDF and LERF depends on the proposed change in CDF and LERF. When the PRA is not full scope, the licensee should address the significance of the out-of-scope items, as discussed in Regulatory Positions C.2.5 of RG 1.174 and C.2.2.3.1 of this guide. RG 1.175, Page 16 2.2.3.3.1 Modeling the Impact of Changes resulting from the Proposed Risk-Informed Inservice Testing Program In order for the PRA to support the decision appropriately, the proposed RI-IST program should have a functional mapping between the components associated with the RI-IST program and the PRA basic event probability quantification. Part of the basis for the acceptability of the proposed RI-IST program is a quantitative demonstration using a PRA that established risk measures are not significantly increased by the proposed changes to the IST for selected components. To establish this demonstration, the PRA should include models that appropriately account for the change in reliability of the components as a function of the RI-IST program implementation. In general, this will include not only changes to the test interval but also the effects of testing method modifications. Enhanced testing might be shown to improve or maintain component reliability, even if the interval is extended. That is, a better test might compensate for a longer interval between tests. Licensees that apply for substantial increases in test intervals are should address this area; that is, as appropriate, licensees should consider improvements in testing that would compensate for the increased intervals under consideration. As discussed in Section 5 of NUREG/CR-6141, “Handbook of Methods for Risk-Based Analyses of Technical Specifications,” issued December 1994 (Ref. 20), the total failure probability of