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:
sequently, 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 depending on the application, each of the technical elements and its attributes should be addressed. 1.4 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 that represents the as-built and as-operated plant to the extent needed to support the application. Consequently, the base PRA is maintained and upgraded, where necessary, to ensure it 3 The glossary in this RG provides a definition of the term current good practice. DG-1362, Page 36 represents the as-built and as-operated plant. However, for some applications, the plant may only be in the DC or COL stage of licensing, at which point the plant may not have been built or is not yet operational. At these licensing stages, the base PRA model is intended to reflect the as-designed plant. A PRA application is a documented analysis based in part or whole on a plant-specific PRA that is used to assist in decision making with regard to the design, licensing, procurement, construction, operation, or maintenance of a nuclear power plant. In the context of regulatory activities, a PRA application includes the use of PRA results to support decisions related to any regulated activity regardless of whether the NRC or the licensee makes the decision. Therefore, a process for developing, maintaining, and upgrading an acceptable base PRA is established. This process involves identifying and using plant information to develop and modify the base PRA, including changes to the plant that necessitate changes to the base PRA. The licensee will consider the cumulative impact of those plant changes or PRA model