Inappropriate communications within operational teams can lead to serious
consequences of a system since it can cause lack of exchange of important information to
perform the task to secure the safety of the system in nuclear power plants (NPPs). For that
reason, we studied the communication characteristics of operating teams to provide
insights to prevent inappropriate communications. However, existing studies on the
communication characteristics seem to have problem since they have characterized team
communications from a single perspective. According that, we have developed an
evaluation method to characterize team communications using social network techniques
which can evaluate them from various perspectives which are group cohesiveness,
frequency of communications, degree of hierarchy, and communication contents. In
addition, we suggested some kinds of specific communication characteristics of operating
teams that can reduce the occurrence of inappropriate communications. Eight verbal
protocol data which are audio-visual recorded under emergency training sessions by main
control room (MCR) operating teams are used. As a result of the study, there was negative
relationship between group cohesiveness and the ratio of inappropriate communications
and there is no relationship between frequency of communications and inappropriate
communications. In addition, the degree of hierarchy to electric operators and supervisory
reactor operators was negatively related to the ratio of inappropriate communications.
Moreover, some kinds of specific communication contents are related to the ratio of
inappropriate communications. Consequently, we can evaluate communications
characteristics of operating teams in NPPs and suggest specific characteristics to provide
useful insights to prevent inappropriate communications.