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:
nd Information Requests” (Ref. 44), nor does the NRC staff intend to use the guidance to affect the issue finality of an approval under 10 CFR Part 52, “Licenses, Certifications, and Approvals for Nuclear Power Plants.” The staff also does not intend to use the guidance to support NRC staff actions in a manner that constitutes forward fitting as that term is defined and described in Management Directive 8.4. If a licensee believes that the NRC is using this RG in a manner inconsistent with the discussion in this Implementation section, then the licensee may file a backfitting or forward fitting appeal with the NRC in accordance with the process in Management Directive 8.4. DG-1362, Page 54 GLOSSARY as-built and as- operated These terms refer to the representation in a PRA model of the current plant design, configuration, procedures, and performance data (e.g., component failure rates). as-designed, as-to- be-built, and as-to- be-operated The term as-designed refers to the PRA used to model the plant configuration in the DC or COL stage, in which the plant is not yet built or operated and, therefore, this PRA reflects the plant as it is intended to be built (i.e., as-to-be- built) and as it is intended to be operated (i.e., as-to-be-operated). assumption An assumption is a decision or judgment that is made in the development of a model, implementation of a method, or conducting an analysis in development of a PRA model for modeling convenience or because of lack of information or state-of-knowledge. An assumption is considered to be credible when it has a sound technical basis and the technical basis would receive broad acceptance within the relevant technical community. However, an assumption may be related to scope or level of detail and is made for modeling convenience in the knowledge that a more detailed model would produce different results. base PRA The base PRA is the PRA from which results or insights are derived or that is modified and/or manipulated