Improvement and Optimization of HPR SG Level Control Based on Multiple Nuclear Power Plants’ Historical Data

Steam generator level control is one of the most important control systems in PWR nuclear power plant. Based on the historical data of commissioning and start-up of a GEN-II nuclear power plant, abnormality of SG level control is the main reason for nuclear power plant reactor trip, accounting for the largest proportion, reaching about 50%. In order to improve the safety of SG level control of GEN-III nuclear power plants, HPR has set up the auxiliary function of SG level control for operators(hereinafter referred to as OAF function). According to the simulation test results, based on the historical data comparison and transient analysis of multiple nuclear power plants, and according to the flow characteristics of low load control valves and full load control valves, project team put forward three OAF logic optimization schemes, which enabled the application range of SG OAF to be extended to the full power operation range, guaranty the safety of SG level control, and eliminated the possible hidden risks of reactor trip in advance. In A GEN-III Finnish nuclear power plant which was not modified according to the proposed scheme of this paper, during the SG level test of 25% power platform, the SG level rose, which finally triggered the reactor trip caused by high SG level. The subsequent treatment scheme of the Finnish nuclear power plant is consistent with the optimization scheme of this paper. This paper mainly introduces the principle of SG level OAF function, the discovery process of SG level control defect of a GEN-III nuclear power plant in China, the treatment scheme, and the final implementation effect in HPR nuclear power plant.