Document: NUREG-0800
Document ID: 7916b088-fb90-4163-84fe-027bd315bcc5
Document Type: srp
Title: REVIEW OF RISK INFORMATION USED TO SUPPORT PERMANENT PLANT-
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0717/ML071700658.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19.2
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CFR Title: 

Content:
g attributes that correlate with CCF potential and that affect the application. • Where applicable, the licensee's performance monitoring program addresses a phased implementation approach to reduce the potential for increased incidence of CCFs attributable to the proposed change. A.8 Modeling of Human Performance a. Areas of Review The results of a PRA, and therefore the input it provides to risk-informed decisionmaking, can be very strongly influenced by the modeling of human performance. Plant safety depends significantly on human performance, so it is essential that the PRA treat it carefully. However, the modeling of human performance, typically referred to as human reliability analysis (HRA), is a relatively difficult area; significant variations in approach continue to be encountered, and these can yield significantly different estimates of human error probabilities (HEPs) for what appears to be similar human failure events. The particular values used for HEPs can significantly influence results of the assessment of the impact of a proposed change. In addition to the quantification issue, there are questions related to what kind of human actions can appropriately be credited in the context of a particular regulatory finding. As an example, suppose that PRA results appear to support relaxation of requirements for a component based on the argument that even if the component fails, its failure can be recovered with high probability by operator actions outside the control room. The issues of concern here are whether the modeling of the operator action and the evaluation of the failure probability is appropriate, and whether this kind of credit is the sort of compensating measure that is intended by staff guidance to support justification of a relaxation. One further issue involves the impact of human performance that is not explicitly modeled, but is implicit in certain parameter values. An example is the influence of human performance on initiating event