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:
mation 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 improvements, as needed, on the results of the PRA and applications being performed between any periodic update of the PRA; changes that would impact risk-informed decisions are addressed in the context of the application or implemented prior to the application. The process is performed such that the plant information identified and used in the base PRA reflects the as-designed, as-built, and as-operated plant and is as realistic as possible in assessing the risk. The information sources include the applicable design, operation, maintenance, and engineering characteristics of the plant. For those SSCs and human actions used in the development of the base PRA, the following information is identified, integrated, and used in the base PRA: • plant design information reflecting the normal and emergency configurations of the plant • plant operational information with regard to plant procedures and practices • plant test and maintenance procedures and practices • engineering aspects of the plant design Further, plant walkdowns are conducted to ensure that information sources being used actually reflect the plant’s as-built and as-operated condition. In some cases, corroborating information obtained from the documented information sources for the plant and other information may only be gained by direct observations. It is recognized that at the design and initial licensing stages, plant walkdowns are not possible. Table 14 describes the technical characteristics and attributes needed to for the above types of information. DG-1362, Page 37 Table 14. Summary of Technical Characteristics and Attributes for Information Sources Used in the Base PRA Development Type of Information Characteristics and attributes (See Note) Design • The safety functions required to