Document: NRC Regulatory Guide
Document ID: acab976c-e936-49be-8c59-865767973599
Document Type: regulatory_guide
Title: Guidance for a Technology-Inclusive Content of Application Methodology to Inform the Licensing Basis and Content of Applications for Licenses, Certifications, and Approvals for Non-Light-Water Reactors (Rev. 1)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML2319/ML23194A194.pdf
Revision Date: 2023-09
Chapter: 
Section ID: RG-1.253
CFR Part: 
CFR Title: 

Content:
of meeting the NRC regulatory positions in Section C of Regulatory Guide (RG) 1.247 (for trial use), “Acceptability of Probabilistic Risk Assessment Results for Non-Light-Water Reactor Risk-Informed Activities” (Ref. B-3). Specifically, Regulatory Position C.1 of RG 1.247 and its subsections provide guidance in the following four areas that are collectively assessed to determine the acceptability of a PRA: 1. Scope of a PRA: The scope of a PRA is defined in terms of (1) the metrics used to characterize risk, (2) the radiological sources that may contribute to risk, (3) the plant operating states (POSs) for which the risk is to be evaluated, and (4) the causes of initiating events (hazard groups) that can potentially challenge and disrupt the normal operation of the plant and, if not prevented or mitigated, would eventually result in a radioactive release. The scope of a PRA that supports a CP application is determined by its intended uses for representing the as-designed, as-to-be-built, and as-to-be-operated plant. 2. Level of detail of a PRA: The level of detail of a PRA is defined in terms of the resolution of the modeling used to represent the behavior and operations of the plant. A minimal level of detail is necessary to ensure that the impacts of designed-in dependencies (e.g., support system DG-1404, Revision 1, App. B, Page 2 dependencies, functional dependencies, and dependencies on operator actions) are correctly represented. This minimal level of detail is implicit in the elements comprising the PRA and their associated characteristics and attributes. 3. Elements of a PRA: The PRA elements are defined in terms of the fundamental technical analyses used to develop and quantify the PRA model for its intended purpose (e.g., determination of a specific risk metric). The characteristics and attributes of the PRA elements define specific criteria for successfully performing those technical analyses and achieving a defined objective. 4. Plant representation