Document: NUREG-0800
Document ID: 51b93b24-7bff-4144-949f-36812854b7aa
Document Type: srp
Title: HUMAN FACTORS ENGINEERING
Source: NUREG-0800
Source URL: https://www.nrc.gov/docs/ML1612/ML16125A114.pdf
Revision Date: 2023-06
Chapter: 18
Section ID: 18.0
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Content:
Even when tasks are performed accurately and on time, high workload causes performance to be “fragile,” in that there may be little or no margin for dealing with added complications. If additional complications are encountered, the workload level may rise to the point where task performance is negatively impacted. Thus it’s important to know that not only is task performance acceptable, but workload levels are not excessive. In addition to workload, there are other factors that impact task performance. For example, failure to properly monitor the plant, or inattention, can also cause tasks to be delayed or overlooked. This condition is sometimes caused by “underload,” i.e., insufficient workload. Insufficient workload is a concern in highly automated plants where the operator’s primary role is monitoring and supervisory control. Operators perform best when workload is neither too high nor too low. Another factor impacting task performance is situation awareness. A crew may not perform a task accurately and on time because they have a misunderstanding of the current plant state. In this case they may not perform the necessary tasks because they do know they need to be done. Poor situation awareness can result from high workload because the workload does not provide staff with the time necessary to maintain accurate situation awareness. High workload, inattention, and poor SA are examples of the factors that can lead to poor task performance and hence should be considered in staffing evaluations. NUREG-7190 provides additional information on analysis methods for these factors. This appendix supplements the guidance in the body of this chapter, NUREG-0711 and NUREG-1791, and is primarily focused on methods to assess workload during the task analysis phase of HFE design. The task analysis results, in turn, support the staffing and qualification analysis. 18.0-32 Revision 3 – December 2016 METHODOLOGY TO ASSESS THE WORKLOAD OF CHALLENGING OPERATIONAL