Optimization Research on Reactor Control System Under Mode-C Operation Control Mode

At present, the main operating control modes used in pressurized water reactor (PWR) nuclear power plants in service are Mode-A, Mode-G, and MSHIM mode, each with its own characteristics. In recent years, China National Nuclear Corporation Limited has proposed a new Mode-C operating control mode during the research and development of the advanced Hualong nuclear power plant (NPP). This Mode-C mode integrates the advantages of Mode-A, Mode-G and MSHIM mode. Reactivity compensation and power distribution control for load-following operation are automatically completed by the reactor power control system, achieving load-following without boron adjustment, which significantly reduces the operator's burden. For base load operation, only one control rod group is inserted into the core to complete the nuclear power plant control tasks, avoiding the reduction in safety margin and certain economic losses caused by the long-term insertion of a large number of control rods in the MSHIM mode during base load operation. This paper, based on the characteristics of Mode-C operating control mode and the design requirement of reduced condenser steam dump capacity for advanced Hualong NPP, discusses the control strategies and optimization research on the reactor control system under the new operating control mode and design requirements. The research results lay the foundation for the practical engineering application of the reactor control system under Mode-C.