Comparing the subjective task difficulty of human operators with task description levels

Without the loss of generality, it is reasonable to say that an operating procedure consists of many steps including detailed descriptions that provide necessary information in conducting the required tasks safely and effectively. In this regard, since it is widely perceived that procedures are effective for reducing the occurrence of human performance related problems, the use of procedures is very popular in large process control systems including nuclear power plants (NPPs), commercial airplanes and railway systems. However, the secure of an operational safety by using an operating procedure can be accomplished only if human operators are able to effectively obtain necessary information from it. In other words, it is hard to expect the reduction of human performance related problems, if task descriptions are so ambiguous or incomplete that human operators feel an undue difficulty in identifying 'what have to be done' and 'how to do it' from procedures. Unfortunately, it seems that a systematic method that can be used to distinguish the proper level of task descriptions is rare. For this reason, Park et al. developed a decision chart that could be helpful for characterizing the level of task descriptions. In this study, in order to ensure the appropriateness of the suggested decision chart, more detailed investigations were conducted with the support of human operators who are working as the operating personnel of NPPs