一回路动态排气剩余空气体积标准值提升后冷却剂流动特性研究

针对动态排气后提升一回路剩余空气体积标准值的改进方案，提出含高溶解度空气的冷却剂在主泵启动瞬态下的压力预测方法和是否释放为两相分离流动的判断方法，对一回路及其辅助系统进行热工水力建模，空气体积标准值提升为24标准立方米（1标准立方米=1.293 kg）后，对主泵启动的瞬态过程进行了仿真，得到了一回路主要节点压力变化规律；结合冷却剂中气体溶解-释放模型，得到饱和氮气溶解度、氧气溶解度变化规律。结果表明，主泵启动瞬态过程中，一回路主要节点压力均在机组运行正常范围内，一回路中溶解的氮气、氧气不会释放成为两相流动。因此，就流动特性而言，空气体积标准值提升到24标准立方米可行。 

Study on Coolant Flow Characteristics for Residual Air Criteria Improvement of Primary Loop Dynamic Venting

According to the improvement proposal for the residual air criteria of the primary loop dynamic venting, the pressure prediction method for the main primary nodes and the judgment method for the two-phase coolant flow are investigated. The thermo-hydraulics model for the primary loop and its auxiliary systems are proposed. When the residual air criteria is raised to 24 normal cubic meters, the startup transient process of reactor coolant pumps are simulated with the models, to obtain the pressure of the main nodes in the primary loop. Based on the gas resolution and released model, the change trend of nitrogen saturation solubility and oxygen saturation solubility are obtained. The results indicate that the pressures of the main nodes are within the normal operation limit; the nitrogen and oxygen cannot release from the coolant and cannot form a two-phase flow. Therefore, in terms of the coolant flow characteristics, the improvement for the residual air criteria to 24 normal cubic meters is feasible.