Operator’s cognitive, communicative and operative activities based workload measurement of advanced main control room

• An advanced MMIS in the advanced MCR requires new roles and tasks of operators.
• A new workload evaluation framework is needed for a new MMIS environment.
• This work suggests a new workload measurement approach (COCOA) for an advanced MCR.
• COCOA enables 3-dimensional measurement of cognition, communication and operation.
• COCOA workload evaluation of the reference plant through simulation was performed.

An advanced man–machine interface system (MMIS) with a computer-based procedure system and high-tech control/alarm system is installed in the advanced main control room (MCR) of a nuclear power plant. Accordingly, though the task of the operators has been changed a great deal, owing to a lack of appropriate guidelines on the role allocation or communication method of the operators, operators should follow the operating strategies of conventional MCR and the problem of an unbalanced workload for each operator can be raised. Thus, it is necessary to enhance the operation capability and improve the plant safety by developing guidelines on the role definition and communication of operators in an advanced MCR. To resolve this problem, however, a method for measuring the workload according to the work execution of the operators is needed, but an applicable method is not available. In this research, we propose a COgnitive, Communicative and Operational Activities measurement approach (COCOA) to measure and evaluate the workload of operators in an advanced MCR. This paper presents the taxonomy for additional operation activities of the operators to use the computerized procedures and soft control added to an advanced MCR, which enables an integrated measurement of the operator workload in various dimensions of cognition, communication, and operation. To check the applicability of COCOA, we evaluated the operator workload of an advanced MCR of a reference power plant through simulation training experiments. As a result, the amount of high workload of the shift supervisor (SS) was observed in relation to the computerized procedure system newly introduced into the environment of an advanced MCR, and the overall increase in the workload was also observed owing to the screen operation for the soft control of MMIS. On the basis of these observations, it is necessary to reestablish the role and communication method of MCR operators suitable to the new operational environment and changed work, and develop appropriate operating guidelines.