Document: NUREG-0800
Document ID: ac43f632-9db1-4857-9f56-bfba45965456
Document Type: srp
Title: * These are modifications to a plant’s design, operations, or other activities that require NRC approval. These modifica
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML0232/ML023250195.pdf
Revision Date: 2023-06
Chapter: 19
Section ID: 19
CFR Part: 
CFR Title: 

Content:
res 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 questions: • 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 SRP 19-A17 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, etc.; the time available to perform the task; the quality of the training (type and frequency) on the specific event; the crew interactions and their potential for recovery from errors; and the stress on the operators, • Whether the human action dependency analysis is affected, • Whether the application introduces or modifies dependencies between plant instrumentation and human actions, • whether the screening analysis is affected. When HFEs represent responses to failures of the SSCs impacted by the change, reviewers may want to focus their resources on these