Application of computer-based operator instruction system to plant diagnosis on fission product transport and release in nuclear power plants

A computer-based operator instruction system (COINS) for diagnosing fission product (FP) transport and release in nuclear power plants (NPPs) is applied to plant diagnosis in combination with the computational code ''SACHET'', which evaluates the dynamic FP inventories in the multiple compartment system of pressurized water reactor (PWR) plants. The COINS can be described in the most general way as a computer-based information processing system which takes in plant data, processes it, and displays the result to the NPP's operating crew. Our major concern for the COINS is, however, not to evaluate general plant dynamics, but to monitor the distribution of the whole radioactive materials such as FP, and to diagnose the plant state in the view of FP transport during the NPP's lifetime. An algorithm of the stochastic approximation for the adaptive pattern classification of the dynamic distributed parameter system is introduced in the COINS software, where a nonlinear functional of the set of monitored data and the system parameters is used. By the use of the COINS, it becomes possible to understand PWR plant states precisely in the view of FP transport and release during normal operation, to identify the occurrenses of the unusual events clearly, and to forecast the potential hazards reasonably. (author)