Investigating the effect of task complexities on the response time of human operators to perform the emergency tasks of nuclear power plants

For many decades, since the reliable performance of human operators is decisive for securing the safety of large process control systems, proceduralized tasks have been widely used to enhance their performance. For this reason, TACOM measure has been developed to quantify the complexity of proceduralized tasks to be conducted by operating personnel working in nuclear power plants (NPPs), because it is strongly expected that complicated tasks could directly result in the degradation of human performance. This expectation seems to be supported by comparing two kinds of human performance data (response time data and subjective workload scores) obtained from the simulated emergency situations of domestic NPPs with the associated TACOM scores. In addition, the results of previous studies make it possible to assume that the performance of human operators would be comparable if they have to accomplish a series of proceduralized tasks having similar levels of task complexities. In this study, in order to scrutinize the appropriateness of this assumption, response time data originated from domestic as well as overseas NPPs were compared with the associated TACOM scores. As a result, it was observed that TACOM scores are important to explain the changes of response time data collected from both the domestic and the overseas NPPs. Therefore, although additional studies are indispensable, this result is meant to show that the performance of human operators would be largely affected by the levels of task complexities, which can be properly quantified by TACOM measure.