Document: NRC Regulatory Guide
Document ID: cde52d5a-adf9-49be-9d1f-59449dfca895
Document Type: regulatory_guide
Title: TRIAL - Acceptability of Probabilistic Risk Assessment Results for Non-Light Water Reactor Risk-Informed Activities
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2123/ML21235A008.pdf
Revision Date: 2023-05
Chapter: 
Section ID: RG-1.247
CFR Part: 
CFR Title: 

Content:
s, CC-I may be acceptable for some requirements. The requirements in an ASME/ANS PRA standard are either process related or technical. Process-related requirements address the process for development, application, maintenance and upgrade, and peer review of a PRA and its results (including resolution of the F&Os) used in support of an application. The technical requirements address the elements of the PRA and what is necessary to acceptably perform that element. For process-related requirements, the purpose is generally straightforward, and the requirement is either met or not met. For the technical requirements, it is not always as straightforward. Many of the technical requirements in an ASME/ANS PRA consensus standard are applied more than once in developing the PRA model. For example, the requirements for systems analysis in an internal events, at-power PRA apply to all systems modeled, and certain data requirements apply to all parameters for which estimates are provided. If the requirement has been met for the majority of the systems or parameter estimates, and any mistakes or oversights are identified as isolated instances, the staff may consider the requirement to be met. If, however, there is a systematic failure to address the requirement (e.g., component boundaries have not been defined anywhere), then the requirement has not been met. In either case, instances of noncompliance with the requirements in an ASME/ANS PRA standard are to be (1) rectified or demonstrated not to be relevant to the application and (2) documented accordingly. Further, the technical requirements may be defined at two different levels: (1) high-level requirements (HLRs) and (2) supporting requirements (SRs). HLRs are defined for each PRA element and are intended to achieve the objective of the PRA element. HLRs are defined in general terms, should be met regardless of the CC, and accommodate different approaches. SRs are defined for each HLR and are the minimum requirements needed