基于SCDAP/RELAP5耦合堆腔注水的非能动压水堆熔融池冷却分析

采取堆腔注水策略冷却熔融池对缓解严重事故后果、降低安全壳的失效概率具有十分重要的作用。本文采用SCDAP/RELAP5程序,首先以韩国APR1400相关实验结果对堆腔外部注水自然对流冷却能力进行比对分析,然后建立了耦合堆腔注水措施的融熔池冷却的核电厂模型,以非能动压水堆为研究对象,针对冷段大破口失水事故(LBLOCA)始发严重事故序列,分析堆芯熔融进展过程中实施堆腔注水策略后融熔池的冷却特性及堆腔外部注水的自然循环能力。分析结果表明,LBLOCA下,当堆芯出口温度达到923K时,实施堆腔注水后能有效冷却下封头内的熔融池,从而保持压力容器的完整性。

Analysis on Molten Pool Cooling Coupled with Cavity Flooding Based on SCDAP/RELAP5 Code for Passive PWR

Molten pool cooling by cavity flooding strategy plays an important role to mitigate severe accident consequences and decrease the containment failure probability. SCDAP/RELAP5 code was used in this paper. Firstly, the code calculation results were compared with the Korea experiment of APR1400, and the capability for natural circulation cooling analysis with cavity flooding was validated. Then, the model of a passive PWR was built for analyzing molten pool cooling coupled with cavity flooding strategy. For severe accident induced by large break loss of coolant accident (LBLOCA) at cold leg, molten pool cooling characteristics during core damage progression were analyzed. After cavity flooding strategy was implemented, heat removal capability by the natural circulation was also analyzed. The results indicate that molten pool in the lower head can be effectively cooled by cavity flooding after core exit temperature exceeds 923 K during LBLOCA, and the integrity of RPV can be maintained.