Development of a diagnostic expert system for secondary water chemistry

Water chemistry control for the secondary side of the PWR plants is one of the most important tasks for maintaining the reliability of plant equipment and for extending the operating life of the plant. Water chemistry control should be maintained according to the plant chemist' considered judgement which is based on continual experienced observation. Mitsubishi Heavy Industries (MHI) has been developing a comprehensive data management and diagnosis system, which continuously observes the secondary water chemistry data with on-line monitors, immediately diagnosing causes whenever any symptoms of abnormality are detected and does the necessary data management, in order to support plant staff to controll water chemistry. This system has the following three basic functions: data management, diagnosis and simulation. This paper presents the outline of the total system, and then describes in detail the procedure of diagnosis, the structure of the knowledge and its validation process