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:
stification • The documentation is sufficient to facilitate independent peer reviews. • The documentation describes the interim results (sufficient to provide traceability and defensibility of the final results) and the final results, insights, and sources of uncertainties. • Walkdown process, where applicable, and results are fully described. 1.3 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. For each given technical element, the level of detail modeled in the base PRA may vary. The detail may vary from the degree to which (1) plant design and operation is modeled, (2) specific plant experience is incorporated into the model, and (3) realism is incorporated into the analyses that reflect the expected plant response. Regardless of the level of detail developed in the base PRA, the technical characteristics and attributes should be addressed. That is, each characteristic and attribute is always addressed, but the degree to which it is addressed may vary. In general, the level of detail for the base PRA is consistent with current good practice.3 The level of detail needed in a PRA that supports a risk-informed decision is dependent on the application. The application may involve using the PRA during different plant “stages” (i.e., design, construction, and operation). Consequently, a PRA used to support a DC may not have the same level of detail as a PRA of a plant that has several years of operating experience. While it is recognized that the level of detail may vary