Exploring Measures of Workload, Situation Awareness, and Task Performance in the Main Control Room

Abstract

Performance based evaluations are commonly completed as part of the human factors verification and validation of control rooms of new builds or substantial modernizations in Nuclear Power Plants. The validation of the Main Control Room system in the nuclear industry entails the assessment of specific performance components such as plant performance, situation awareness, workload, task performance, and anthropometric and physiological factors. This evaluation is expected to take place in realistic contexts, simulating the plant's operation and covering also abnormal and emergency operation situations. There is a vast set of measures to address these human performance components, and the relations among the different concepts and different measures are not clearly defined. The measures used to assess human performance can also vary significantly regarding the type of rater (self-rated, observer-rated, objective ratings), the type of scale (rating scales, correct/incorrect decisions, open answer, acceptability judgments), the moment of rating (online rating, end of scenario, scenario freezes), among others. In this paper we try to analyze these relationships between task performance, workload, and situation awareness. We explored the results of both self-rated, observer-rated, and objective measures. We explored the relations between and within measures, as well as the trends across the different assessments, affected by control room modifications. The results indicate a similar pattern in workload and situation awareness measures through evaluations; that the relations within self-rated measures appear to be clearer than between self-rated and observer-rated measures; and that there seems to be a trend for improved task performance results in the control room throughout the years.