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:
tely adjusting the test intervals of LSSCs to the maximum proposed test interval. Normally, test interval increases will be done stepwise, with gradual extensions permitted, consistent with cumulative performance data for operation at the extended intervals. The actual testing intervals for each component in the RI-IST program should be available at the plant site for inspection. The tests described in the current OM Code assure that components relied on to safely shutdown the reactor, maintain it in a safe shutdown condition, and mitigate the consequences of an accident are RG 1.175, Page 23 able to perform their specified safety function(s) when required by plant conditions. However, enhanced tests, even at an extended test interval, may be more effective for detecting the important failure modes and causes of a component or group of components. HSSCs that are not in the current IST program should be tested, where practical, in accordance with the OM Code, including compliance with all administrative requirements. When OM Code testing is not practical, the licensee should develop alternative test methods to ensure operational readiness and to detect component degradation (i.e., degradation associated with failure modes identified as important in the licensee’s PRA). An acceptable method to extend the test interval for LSSCs is to group like components and stagger their testing equally over the interval identified for a specific component based on the probabilistic analysis and deterministic evaluation of each individual component. Initially, it would be desirable to test at least one component in each group every refueling outage. For example, component grouping should consider valve actuator type for power-operated valves and pump driver type, as applicable. With this method, generic age-related failures can be identified while allowing immediate implementation for some components. For component groups that are insufficient in size to test one component every