Document: NRC Regulatory Guide
Document ID: c7a40fcc-fc9d-4eb2-ad86-f9f5b0f04c82
Document Type: regulatory_guide
Title: Plant-Specific, Risk-Informed Decisionmaking:  Technical Specifications (Rev. 2)
Source: NRC Regulatory Guide Division 1
Source URL: https://www.nrc.gov/docs/ML1920/ML19206A489.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-1.177
CFR Part: 
CFR Title: 

Content:
or systems for which TS changes are being considered, plant-specific data should be evaluated, and assurance should be obtained that the data used are consistent with the plant experience. The use of other than plant-specific data should be justified. When a generic analysis uses a representative plant model, the incorporation of generic data from similar plants is acceptable. The generic data should bound the specific plants under consideration, not an average plant. A-2.1 Care in Using Plant-Specific Data When using plant-specific data to update input parameters of the PRA during a TS change evaluation (in addition to those used during the latest update of the PRA), care should be taken to ensure that such data are consistently used both for the base case, where existing TS requirements apply, and the change case, where TS changes are incorporated. This provides assurance that the increase in the risk measure obtained is associated with the TS change only and not with the use of plant-specific data in aspects of plant operation. This situation typically arises when recent plant-specific data are evaluated and reduced values of the parameters are obtained. Use of the reduced values may negate the risk increase from the TS change and may give an erroneous impression that the TS change has reduced the risk. When the base case is also updated, such difficulties are avoided. Sensitivity and uncertainty analyses should also be performed using the same set of input data. A-2.2 Considerations When Generic Data Are Used When using generic data for the TS parameters in evaluating TS changes, the focus should be on justifying small changes that do not strongly depend on the data parameters. The reasons why generic data are being used and why generic data apply to plant-specific evaluations should be presented. In many cases, because of limited experience, the use of plant-specific data may result in very optimistic values justifying the use of generic data. DG-1287,