A study on the development of a task complexity measure for emergency operating procedures of nuclear power plants

In this study, a measure called task complexity (TACOM) that can quantify the complexity of tasks stipulated in emergency operating procedures of nuclear power plants is developed. The TACOM measure consists of five sub-measures that can cover remarkable complexity factors: (1) amount of information to be managed by operators, (2) logical entanglement due to the logical sequence of the required actions, (3) amount of actions to be accomplished by operators, (4) amount of system knowledge in recognizing the problem space, and (5) amount of cognitive resources in establishing an appropriate decision criterion. The appropriateness of the TACOM measure is investigated by comparing task performance time data with the associated TACOM scores. As a result, it is observed that there is a significant correlation between TACOM scores and task performance time data. Therefore, it is reasonable to expect that the TACOM measure can be used as a meaningful tool to quantify the complexity of tasks.