小型核动力装置抽真空启动过程热力特性及含氧量变化实验研究

Experimental Study on Thermal Characteristics and Oxygen Concentration during Vacuum Refill Startup of Small Nuclear Power Plant

在压水堆核动力装置启动阶段采用抽真空的方式对一回路系统进行抽气除氧,可以控制一回路冷却剂含氧量、减缓材料腐蚀并加快启动速度。为研究小型核动力装置一回路系统的抽真空启动特性,设计并搭建了小型核动力装置抽真空启动实验系统,通过实验获得了回路在抽气、注水、建立汽腔及升温升压过程中的温度、压力以及含氧量变化规律。结果表明:对于小型核动力装置,采用抽真空方法可以实现半小时左右完成抽气及注水过程,且回路冷却剂的溶解氧低于0.1×10^(-6)(质量分数);在抽真空过程中达到的真空度越高,启动过程中回路内冷却剂含氧量越低;通过分析启动过程中不同抽真空压力下的回路冷却剂含氧量,发现在水装量较小的核动力装置中,回路中未溶解的氧占有较大比重,需要进一步对氧气溶解的瞬态过程进行分析。

During the startup stage of PWR nuclear power plant,the primary system is evacuated and deaerated by vacuumizing method.It can control the oxygen concentration of primary coolant,slow down material corrosion and speed up the start-up speed.In order to study the operating characteristics of the primary circuit system of small nuclear power plant during vacuum refill startup,the experimental device was designed and established.The change of temperature,pressure and oxygen concentration parameters were obtained in the process of vacuumizing,water refill,steam chamber establishment,and temperature-pressure increasing.The results show that:for small nuclear power plant,the vacuumizing and water refill process can be completed in about half an hour by vacuumizing method,and the dissolved oxygen of the loop coolant is less than 0.1 ppm;During the vacuumizing process,the higher the vacuum degree in the primary loop,the lower the oxygen concentration of the coolant.By analyzing the oxygen concentration of the circuit coolant under different vacuuming pressures during the start-up process,it is found that in the nuclear power plant with a small quantity of water,the undissolved oxygen in the circuit occupies a large proportion,and further analysis of the transient process of oxygen dissolution is required.