Selecting HLR and SR Standards for PRA Applications Available to Purchase

This white paper provides guidance for mapping risk informed applications to PRA Scope and Technical Adequacy requirements. The discussion considers regulatory guidance contained in SRP 19.1 “Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk Informed Activities” and supplements industry guidance on application mapping contained in Section 3 “Risk Assessment Application Process of the ASME Standard for the PRA for Nuclear Power Plant Applications,” of the ASME PRA Standard with Regulatory Guide 1.200 clarifications. The general processes identified in this paper should also be applicable to mapping applications to any of the forthcoming ANS standard requirements. The aim of this white paper is to help identify which ASME PRA Standard High Level Requirements (HLRs) fall in the scope of a particular “risk informed” application to the NRC that will, in part, justify the requested change with risk metrics. To obtain values for risk metrics, it is necessary to manipulate the plant PRA model. The question becomes what should be changed in the model to represent the “risk informed” topic at hand? Each HLR has a set of supporting requirements (SRs) graded by “Capability Categories.” For many supporting requirements (SRs) under each HLR, there is no difference between the three capability categories. At issue is what features of the model have to conform to Capability Category 2 when Capability Category 2 differs from Capability Category 1.