A novel speech-act coding scheme to visualize the intention of crew communications to cope with simulated off-normal conditions of nuclear power plants

•Crew communication is critical input for the safety of complicated systems.•Existing speech-act coding schemes mainly emphasize what was done.•3657 utterances were analyzed in order to identify 45 behavioral task categories.•A novel speech-act coding scheme emphasizes a communication intention. Many researchers have commonly pointed out that the characteristics of crew communications is one of the most important factors affecting the operation safety of complicated process control systems. From this concern, a couple of speech-act coding schemes were developed from the point of view of ‘what was done by crew members?’ In this study, a novel speech-act coding scheme was developed, which allows us to see the contents crew communication from a different angle – ‘what was the communication intention of crew members?’ To this end, the communication contents uttered by MCR operators who were faced with various kinds of simulated off-normal conditions were collected from the full-scope simulator of domestic NPPs. Then, the novel speech-act coding scheme was developed by involving additional yardsticks (such as Means, Acceptance criteria, and Constraints), which are useful for elucidating the nature of communications from a task description perspective. As a result, the novel speech-act coding scheme was proposed, which consists of 45 behavioral task categories and the associated definitions. Although the novel speech-act coding scheme proposed in this study is still a preliminary version, this would be a good starting point to enhance the quality of crew communications through visualizing their communication intentions.