Guidance for the Review of Changes to Human Actions (NUREG-1764, Rev. 1)

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Publication Information

Manuscript Completed: January 2005
Date Published: September 2007

Prepared by:
J.C. Higgins and J.M. O'Hara
Energy Sciences and Technology Department
Brookhaven National Laboratory
Upton, NY 11973-5000

P.M. Lewis, J.J. Persensky, J.P. Bongarra, S.E. Cooper, and G.W. Parry
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Prepared for:
Division of Risk Assessment and Special Projects
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

The U.S. Nuclear Regulatory Commission (NRC) reviews changes in human actions, such as those that are credited in nuclear power plant safety analyses. This document provides guidance for reviewing those changes. In this document, the terms “human action” and “operator action” are used synonymously because most of the types of actions discussed are performed by operations staff. The evaluation method uses a two-phased approach. The first phase is a screening analysis of the licensee’s proposed modification and the affected human actions to assess their risk-importance. A graded, risk-informed approach is used to determine the appropriate level of human factors engineering review. This approach can be accomplished for licensee submittals that are either risk-informed or non-risk-informed. For risk-informed submittals, the first phase has four steps: (1) use of Regulatory Guide (RG) 1.174 to determine the risk-importance of the entire plant change or modification that involves the human action, (2) quantification of the risk-importance of the human action itself, (3) qualitative evaluation of the human action, and (4) integrated assessment to determine the appropriate level of human factors engineering review. For non-risk informed submittals, a similar process is used which includes the use of generic risk information to determine the safety significance of the HA in place of the first two steps used in a risk-informed submittal.

The proposed human actions are assigned to one of three risk levels (high, medium, and low) as a result of Phase 1. The level of human factors engineering review in the second phase corresponds to these risk levels. In the second phase, human actions are reviewed using standard human factors engineering criteria to ensure the appropriate conditions are in place so that the change in human action does not significantly increase the potential for risk. Human actions in the high risk level receive a detailed human factors engineering review, while those in the medium risk level undergo a less detailed review, commensurate with their risk. For human actions in the low risk level, there is a minimal human factors engineering review or none. The NRC's review of licensee submittals that involve changes to human actions is an iterative process. The final results of the human factors engineering review provide input to integrated decision-making and a safety evaluation report.

This revision (Rev. 1) contains relatively minor changes and clarifications in the text (virtually all of them in Chapter 2). Appendix B lists the most significant changes.