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:
cope PRA is used to support the proposed RI-IST program, supplemental information (deterministic and qualitative) should be considered during the integrated decisionmaking process. Regulatory Position C.2.2.3.2 provides more specific considerations to address this condition. For the PRA to be useful in the development of an RI-IST program, the PRA model should be developed to the component level for the systems, including nonsafety systems, considered important for the prevention of core damage and release of radioactivity. A PRA used for an RI-IST program should be performed correctly and in a manner that is consistent with accepted practices. The PRA should reflect the actual design, construction, operating practices, and operating experience of the plant. The acceptability of the PRA used for an RI-IST program should be commensurate with the role it plays in determining test intervals or test methods and with the role the integrated decisionmaking panel plays in compensating for the limitations of the PRA. RG 1.174 further discusses the requirements of PRA acceptability. 2.2.3.2 Categorization of Components The categorization of components is important in the implementation of the RI-IST program because it is an efficient and risk-informed way of providing insights in the areas in which certain requirements can be relaxed with assurance of continued adequate protection. Thus, categorization of components, in addition to the engineering evaluation described in Regulatory Position C.2.2 and the calculation of change in overall plant risk described in Regulatory Position C.2.2.3.3, will provide significant input to the determination of whether the IST program is acceptable or not. The establishment of the safety significance of components by using PRA-determined importance is valuable for the following reasons: RG 1.175, Page 14 a. When performed with a series of sensitivity evaluations, the use of PRA to determine importance can identify potential risk outliers by