核电站重要厂用水系统两阶段关阀方案分析

核电站重要厂用水系统负责把设备冷却水系统收集的热量输送至最终热阱（一般为大海），该系统必须长期安全、稳定运行。为便于核电站重要厂用水系统的设计和优化，以某核电厂为例，利用PIPENET软件对水力瞬态的计算功能，对其重要厂用水系统停泵后水锤过程进行建模模拟计算，分析泵后止回阀在不同的两阶段关阀方案下的液柱分离、阀后压力以及水泵机组倒流百分比等问题。经多方案比选后，提出止回阀两阶段关阀推荐方案：阀门快关时间为4 s，缓关时间为7 s。模拟结果表明，该方案既显著降低了泵的反转率，又保证了水锤产生的压力低于设计压力。

Analysis of Two-Stage Valve Shutdown Scheme in Essential Service Water System of a Nuclear Power Plant

The essential service water system of a nuclear power plant is the DC water heat transport system from the auxiliaries cooling water system to the sea, whose long-term safe and stable operation must be ensured. The pump-stop water hammer of the essential service water system of a nuclear power plant is simulated with transient calculation function of PIPENET software for system design and optimization. The issues of liquid column separation, outlet pressure and pump backflow are analyzed for the check valve downstream from the pump through the simulation. An optimized scheme of shutdown durations of 4 s and 7 s for the quick and the slow stages respectively is obtained through the scheme comparison. The simulation results show that the scheme can not only significantly reduce the reverse rotation of pump, but also ensure the water hammer pressure lower than the designed value.