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
CFR Part: 
CFR Title: 

Content:
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 frequency. The causes of initiating events are typically not addressed; their impact is included in the frequency in an implicit way. b. Review Guidance and Procedures 19.2-55 June 2007 Reviewers should understand the potentially significant human performance issues that might be affected by the application and how these are reflected in the PRA. This understanding requires a review of the approach used to estimate human error probabilities. The HRA can impact the assessment of the change in several ways. First, the change may directly affect the human failure events (HFEs). Second, the HFEs may represent responses to failures of the SSCs impacted by the change. Finally, HFEs unrelated to the change can obscure or exaggerate the impact of the change (depending on their values) by inappropriately increasing or decreasing the value of the accident sequences unaffected by the change. When the change directly impacts the HFEs (e.g., as a result of a procedure change or a change in operating practice), reviewers should ensure that the licensee appropriately modeled the impact; that is, reviewers should ensure that the licensee addressed the following considerations: • Whether new human actions are introduced or whether existing actions are modified or eliminated, • Whether the change affects factors assumed to impact the likelihood of failure (usually called performance shaping factors or PSFs), including the quality of the procedures; the cues available to the operators; the quality of the information (instrumentation) available to the operators; the quality of the human-machine interface; the location of the interface(s); the complexity of the task; the conditions or context within which the operators are responding, including previous failures, previous actions,