大型非能动压水堆核电厂安全注射系统旋启式止回阀阻力变化对长期堆芯冷却影响分析

大型非能动压水堆核电厂在发生失水事故(LOCA)后的长期堆芯冷却阶段依靠重力向堆芯注入应急冷却水,其注射管线上设置的旋启式止回阀的阻力可随流量变化,管线的阻力可能将非预期地增加。根据旋启式止回阀阻力特性,为失水事故最佳估算系统分析程序添加相应的计算功能,对压力容器直接注射(DVI)管线双端断裂事故后长期堆芯冷却工况进行了计算分析。结果表明:安全注射管线上旋启式止回阀阻力变化对大型非能动压水堆核电厂LOCA后长期冷却的影响较小;在安全裕量不足的情况下,旋启式止回阀的阻力特性将影响到非能动注射管线的安全注射功能的执行。

Analysis of Influence of Swing Check Valve Resistance Variation in Safety Injection System on Long Term Core Cooling in Large Advanced Passive PWR Nuclear Power Plant

The emergency cooling water is injected into the reactor core by gravity in the large advanced passive PWR nuclear power plant during the long term core cooling (LTCC) following loss of coolant accident (LOCA). The resistances of swing check valves in the safety injection lines vary with flow rate causing unexpected increase in the resistance of safety injection lines. A model according to the swing check valve resistance performance was implemented into the best-estimate LOCA analysis system code in this study. The cases of LTCC following a guillotine double-ended direct vessel injection (DEDVI) line break were analyzed using the improved code. Compared with the previous calculations, it’s found that the swing check valve resistance performance has a little effect on LTCC following a LOCA in the large advanced passive PWR nuclear power plant but is important to the ability of safety injection in some situations with inadequate safety margin.