Prediction and comparison were conducted on the molten core-concrete interaction in the mixed and stratified pool configurations in a mega kilowatt pressure water reactor plant by using the code MEDICIS modeling methods in the aspects of poolconcrete interface and heat transfer.The results show that the mean pool temperature is close to the molten core solidification temperature,the cavity ablation behaves isotropically,and the final temperature and pressure do not reach the designed values in the mixed pool configuration,while the mean pool temperature is far above the corium solidification temperature,the cavity ablation behaves anisotropically and the lateral ablation prevails,and the final temperature and pressure are very close to the designed values in the stratified pool configuration.Also in the both pool configurations,the concrete basemat is ablated quite slowly,the time of basemat melt-through in the containment may exceed a week for a 4 m thick basemat,the large masses of steam and incondensable CO,CO2 and H2 are produced in the containment,and there exists a risk of gas combustion and detonation which may be a threat to containment integrality.%基于在熔池-混凝土界面结构、对流传热和熔融物层间传热3个方面的MEDICIS程序建模方法,针对百万千瓦级压水堆核电厂在混合与分层两种熔池形态下的假想熔融物与混凝土相互作用(MCCI)事故进行预测和对比分析.结果表明:在混合熔池形态下,熔池平均温度接近熔融物固化温度,混凝土堆腔的侵蚀表现为各向同性,安全壳内最终温度和压力均未达到设计值;在分层熔池形态下,熔池平均温度远高于熔融物固化温度,混凝土堆腔的侵蚀表现为各向异性且径向占优,安全壳内最终温度和压力都非常接近设计值.两种熔池形态下的混凝土地基侵蚀过程都很缓慢,厚度为4 m的地基熔穿时间超过1周;安全壳内产生大量的水蒸气以及不可凝结气体CO、CO2和H2,存在气体燃烧和爆炸风险,对安全壳完整性构成威胁.
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