MELCOR2.2冷水入侵和熔融物喷出模型在MCCI计算中的应用

Application of Water Ingress and Melt Eruption Models with MELCOR2.2 in MCCI Computation

堆芯熔融物-混凝土相互作用(MCCI)产生的大量不凝气体导致安全壳压力快速升高,威胁安全壳的完整性。最新版本MELCOR2.2程序增加了冷水入侵和熔融物喷出模型以完善堆芯熔融物-混凝土相互作用现象的模拟。本文建立了大功率非能动压水堆堆腔几何模型,针对程序中添加的冷水入侵和熔融物喷出模型进行了应用分析。结果表明:在混凝土的消融过程中,冷水入侵和熔融物喷出模型的开启对熔融物和水接触面之间的硬质壳层有一定的影响;硬质壳层的反复形成和裂解加快了水的汽化,减弱了混凝土的消融速度;堆腔熔融物上部和侧部硬质壳层形成后,熔融物向下传热加强,混凝土的消融速度增加。新增模型能从细节上模拟堆芯熔融物-混凝土相互作用现象,为压水堆核电厂严重事故安全审评提供可靠技术保障。

The massive non-condensable gases from molten core-concrete interaction(MCCI)cause the containment pressure acceleration,which would threaten the containment integrity.In order to improve the simulation of MCCI progress,the models of water ingress and melt eruption were added into the current released MELCOR version 2.2.In this paper,the cavity geometer of large power passive PWR was modeled,and the application of water ingress and melt eruption added currently was analyzed.The analysis results show that during MCCI progress,the active of the water ingress and melt eruption models influences the crust layer formed on the face between the melt debris and the water pool.The repeated formation and decomposation of crust layer accelerate the vaporization of the water,and decrease the ablation rate of the concrete.After the formation of the crust layer on the top and side of the melt debris,the downward transferred heat is enhanced,thus this trend increases the concrete ablation rate.The currently added models have the capability to simulate the MCCI in detail,therefore,it provides reliable technical security for severe accident safety review with PWR NPP.