Testing of the ICMS input data diagnostic system at unit № 1 of Novovoronezh NPP II
A reaL-time input data diagnostic system of the in-core monitoring system (ICMS) was tested for the first time during the commissioning of Unit № 1 at Novovoronezh NPP II. The purpose of the diagnostic systems is to support continuous ICMS input data validity control in connection with the fact that new and upgraded ICMS designs include the performance of safety functions based on local in-core parameters. Tasks are formulated to be solved in the development of the ICMS input data diagnostic system, the structure of the developed system is shown, and the key information on the system operation is provided. There were developed algorithms to define main operating mode of reactor plant and it stationary state for the possibility of functioning in automatic regime. Techniques of estimating the reliability of monitoring channels readings used in diagnose system have been repeatedly verified at ICMS physical tests during commissioning and operation of VVER-1000 power units of different projects. Major system testing results are given, which demonstrate the system to be capable to detect in real time the measuring monitoring channels with invalid readings and to present respective diagnostic data. These results have confirmed that the system is capable to define the measuring monitoring channels with doubtful readings and to give the corresponding diagnostic information. The fulfilled testing has shown, that the developed system can be recommended as project system. It wll allow to raising reliability of functioning ICMS at the expense of automation of some maintenance procedures.