Document: NRC Regulatory Guide
Document ID: 22ccfd5e-c5d8-4615-a02c-32369aa9f533
Document Type: regulatory_guide
Title: Acceptability of Probabilistic Risk Assessment Results for Risk-Informed Activities (Rev. 3)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1930/ML19308B636.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.200
CFR Part: 
CFR Title: 

Content:
o characterize risk, (2) the plant operating states (POSs) for which the risk is to be evaluated, and (3) 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 core damage and/or a large release. The scope of a base PRA is determined by its intended use for representing the as-built and as-operated plant. Regulatory position C.1.1 provides guidance with respect to a full-scope Level 1 and Level 2 PRA. • Technical elements of a base PRA: The PRA technical elements are defined in terms of the fundamental technical analyses needed to develop and quantify the base PRA model for its intended purpose (e.g., determination of a specific risk metric). The characteristics and attributes of the PRA technical elements define specific requirements that should be met to successfully perform those technical analyses and achieve a defined objective. Regulatory position C.1.2 provides guidance on the technical elements of a full-scope Level 1 and Level 2 PRA. • Level of detail of a base PRA: The level of detail of a base 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 dependencies, functional dependencies, and dependencies on operator actions) are correctly captured. This minimal level of detail is implicit in the technical elements comprising the base PRA and their associated characteristics and attributes. Regulatory position C.1.3 provides guidance on the level of detail for a base PRA. • Plant representation and PRA configuration control: Plant representation is defined in terms of how closely the base PRA represents the plant as it is actually built and operated. In general, PRA results used to support an application must be derived from a base PRA model