An investigation of functional model and text presentation for explanation display of counter operation procedure in an emergency situation of plants

In a plant such as nuclear power plants (NPPs), the operators basically take recovery actions following suitable emergency operating procedures (EOPs). If an unexpected event occurs, they are asked to plan and decide the recovery actions by themselves without EOPs. The goal of this study is to support the decision of operators to take suitable counter operations. This study investigates the design of explanation display of counter operation procedures, generated by the technique developed in our previous studies to make action planning, and their generation processes. Because operators feel mental pressure and the cognitive capability of them may deteriorate by the pressure and limited allowance time for taking counter actions in an emergency situation, the explanation display should be designed considering the cognitive characteristics. The explanation display includes a P&ID diagram as the main part, a simple functional model, and text explanations for detailed information to support the understanding of both the candidates of counter operation procedures and their generation processes. The functional model expresses the functions of components and their relations and makes operators understand easily the roles of the components of a plant. A simple and easy understandable functional model based on Multilevel Flow Modeling (MFM) is displayed in this study considering the current education and training of operators for nuclear power plants. In addition, simplified text explanations considering the way of thinking of human in the explanation of complex causal relations are used to display concrete information.