Development and Application of Self-diagnosis and Analysis Function of FirmSys

Abstract

AbstractThe digital control system of a nuclear power plant is mainly used in the protection system of nuclear power plants. The reliability and safety of the protection system directly affect the safe and stable operation of nuclear power plants. Self-diagnosis technology is a key character to improve the system fault handling mechanism. A complete self-diagnosis design could find all kinds of faults in the system in a real-time and comprehensive condition. Self-diagnosis refers to the technology that the system self-detects and processes faults or failure events by setting the diagnosis function. Its goal is to detect failure (failure) events as early as possible, support the system for maintenance recovery or failure safety treatment, reduce the operation time of the system in dangerous or degraded mode, and improve the reliability and safety of the system. The system self-diagnosis and analysis function can effectively reduce human errors and shorten the period and frequency of periodic test. In this case, the function is strongly required by system users. However, there is no public literature on this issue in the field of nuclear safety digital I&C in China, due to a wide range of products, the complexity of implementation and the difficulty of evaluating the impact on safety functions involved. The FirmSys is the first nuclear safety digital control and protection system platform developed and applied in China. Based on the requirement analysis of the fault self-diagnosis and analysis function of the FirmSys, and referring to the requirements of IEC60800 and IEC61508 standards, a design scheme, 'on-line self-diagnosis and off-line analysis of fault log’, is proposed in this paper. Furthermore, the factors affecting the function realization from the perspective of safety analysis is also stated, followed by carrying out targeted safety design. For the products that achieve this function, verification, validation and identification are implemented. The FirmSys platform, which realizes the function of fault self-diagnosis and analysis, has been successfully applied in Unit 5&6 of YangJiang NPP, Unit 5&6 of HongYanHe NPP, Unit 5&6 of TianWan NPP and Unit 3&4 of FangChengGang NPP.KeywordsFirmSysSelf-diagnosisReactor protection systemNuclear safety level