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:
pment operating history, work practices, and the implementation of the Maintenance Rule (Title 10 of the Code of Federal Regulations (10 CFR) 50.65, “Requirements for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants”). Systems design considerations should include the potential effect of different design configurations (e.g., piping, valves, and pumps) on planning for an RI-IST, particularly if contemplating future plant modifications or if systems are temporarily taken out of service for maintenance or replacement or repair. A-3. Specific Areas to be Evaluated This section addresses some technical and administrative issues that are particularly important for RI-IST programs: a. The RI-IST application should confirm that proper attention was given to component classifications in systems identified in emergency operating procedures (and other systems) depended upon for operator recovery actions, primary fission product barriers excluded from the PRA because of their inherent reliability (such as the reactor pressure vessel), passive items not modeled in the PRA (such as piping, cable, supports, building or compartment structures such as the spent fuel pool), and systems relied upon to mitigate the effects of external events in cases where the PRA considered only internal events. b. Failure modes modeled by the PRA may not be all-inclusive. Consideration should be given to the failure modes modeled and the potential for the introduction of new failure modes related to the IST application. For example, if valve mispositioning has been assumed to be a low-probability event because of independent verification, and therefore, is not included in the PRA assumptions, any changes to such independent verifications should be evaluated for potential impact on the PRA results. c. The resource information base should include other qualitative or quantitative analyses that shed light on the relative safety importance of components, such as failure modes and