A nuclear power plant is controlled by an operating team. When an abnormal operating condition occurs during plant start-up or full-power operations, the team has to cope with it. Thus the behavior of the operating team has to be considered when discussing the reliability of nuclear power plant operations. This study develops a method to describe team activities coping with abnormal conditions and determines the characteristics of the team activities when deciding strategies based on the description by this method. As a result, there are 4 types when deciding strategies, such as who makes decisions and whether the team has any communications. Also, the situation that the team is facing changes the way of deciding strategies.