Abstract


Enhancing the operator¡Çs ability to cope with emergent situation is very important in keeping the reliability and safety of Nuclear Power Plant (NPP) operation. When a serious fault occurs in NPP, there appear many alarms on the control panel, and the operators are expected to make the right diagnosis by checking the alarms and to make appropriate counteraction to recover the plant status in accordance with their well-trained skills. Since it is a very tough work for operators dealing with so many alarms rightly in emergent situations, there have been many researches on automatic support system to help operators for NPP. However, the introduction of automatic diagnosis will bring about a problem to the operators. It is welcome that the operators need not do anything by themselves since they can get the diagnosis result from the computer. They can be released from the cumbersome work. But there will be another problem:¡É what if the operators cannot understand the diagnosis result by the support system?¡É If the support system tells them just where and what are wrong in the system without any explanation, they will still think why and doubt: ¡ÈIs it really right?¡É Because of the serious consequence by the operators¡Ç mistrust to automatic support system, it should be also equipped with an important function that the operators can confirm to make sure that the given diagnosis result is true. For this purpose, the operator support system should not only ¡Ègive right diagnosis timely¡É but also ¡Èmake explanation for easy understanding¡É for the operators to confirm all the alarms occurred. In order to achieve the both goals of timely diagnosis and understandability, two methodologies are chosen of the diagnosis support system: one is Multilevel Flow Model (MFM) and the other is the concept of Ecological Interface Design. The MFM is a semantic language to describe the structure and work principle of plant process, and it is used to describe the process of NPP in a graphical way. When fault occurs, the alarms of the plant can be related to the causal reasoning algorithms of MFM to find the root cause with the alarm propagation route. And in the procedure of confirmation of the fault cause, the concept of Ecological Interface Design is combined to represent the alarm-related parameters of the plant in a way that can lead the confirmation action of operators to a level of low cognitive workload which cannot achieved fully by MFM itself. Fig.1 Structure of the prototype system A PWR simulator is used as an online data source and an alarm generator is based on it. Alarm analysis and fault display will be made by using the MFM. Operators will get the diagnosis result from the MFM, and they use the relevant display of Ecological Interface to confirm the fault cause. An evaluation experiment of the system will be conducted using an eye tracking equipment.

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