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:
ng Program. The purpose of this element is to develop the implementation plan for the IST program. This involves determining both the methods to be used and the frequency of testing. The frequency and method of testing for each component is commensurate with the component’s safety significance. To the extent practicable, the testing methods should address the relevant failure mechanisms that could significantly affect component reliability. In addition, a monitoring and corrective action program is established to ensure that the assumptions upon which the testing strategy has been based continue to be valid, and that no unexpected degradation in performance of the HSSCs and LSSCs occurs as a result of the change to the IST program. Regulatory Position C.3 gives specific guidance for Element 3. Element 4: Submit Proposed Change. The final element involves preparing the documentation to be included in the submittal and the documentation to be maintained by the licensee for later reference, as needed. Regulatory Position C.4 gives guidance on documentation requirements for RI-IST programs. The process is highly iterative. Thus, the final description of the proposed change to the IST program as defined in Element 1 depends on both the analysis performed in Element 2 and the definition of the implementation of the IST program performed in Element 3. The regulatory positions in Section C of this RG provide guidance on each element. Although IST is, by its nature, a monitoring program, the monitoring that Element 3 refers to ensures that the assumptions made about the impact of the changes to the IST program are not invalidated. For example, if the test intervals are based on an allowable margin to failure, the monitoring is performed to make sure that these margins are not eroded. In carrying out this process, the licensee will make a number of decisions based on the best available information. Some of this information will derive from deterministic engineering practice