Development of an Integrated Decision Support System to Aid Cognitive Activities of Operators

The main control room (MCR) operators in a nuclear power plant (NPP) have a supervisory role for information gathering, planning, and decision making. Such operation tasks in MCRs are very complex and mentally taxing activities. In safety-critical systems, especially in NPPs, human error is recognized as a serious cause of accidents. Since the 1980s, human error in NPPs has been a considerable concern. In an analysis of the abstracts from 180 significant events reported to have occurred in the United States, it was found that 48% of the incidents were attributed to human-factor failures [1]. In order to prevent human error, many endeavors have been made to improve MCR interface designs and to develop support systems that allow more convenient MCR operation and maintenance. The design of instrumentation and control (I&C) systems for various plant systems is rapidly moving toward full digitalization, with an increased proportion of automation [2]. In addition, as the processing and information presentation capabilities of modern computers increase, the trend is toward the application of modern computer techniques to the design of advanced MCRs for NPPs [3]. By adapting modern computer techniques, advanced MCRs (modernized MCRs) have been much simplified, and now use large display panels (LDPs) and LCD displays instead of analogue indicators, hand switches, and alarm tiles. Furthermore, these computerized systems are aimed to improve operator performance by filtering or integrating the raw process data, interpreting the plant state, prioritizing goals, and providing advice. They also help the operator focus attention on the most relevant data and highest priority problems, and they dynamically adapt the proposed response plans to changing situations. Computerized support of operational performance is needed to assist the operator, particularly in coping with plant anomalies, so that any failures of complex dynamic processes can be managed as quickly as possible with minimal adverse consequences [3]. In NPPs, one of the most serious issues when adapting automated or support systems is whether the operator or the system should be the final decision maker. Should an automated system or support system fail to respond correctly, an operator who detects that failure should be able to override the system’s decision. Considering the operator’s oversight role in such cases, authority for some tasks should be retained by the operator. This problem is called As digital and computer technologies have grown, human-machine interfaces (HMIs) have evolved. In safety-critical systems, especially in nuclear power plants (NPPs), HMIs are important for reducing operational costs, the number of necessary operators, and the probability of accident occurrence. Efforts have been made to improve main control room (MCR) interface design and to develop automated or decision support systems to ensure convenient operation and maintenance. In this paper, an integrated decision support system to aid operator cognitive processes is proposed for advanced MCRs of future NPPs. This work suggests the design concept of a decision support system which accounts for an operator’s cognitive processes. The proposed system supports not only a particular task, but also the entire operation process based on a human cognitive process model. In this paper, the operator’s operation processes are analyzed according to a human cognitive process model and appropriate support systems that support each cognitive process activity are suggested.