熔融物液柱碎化模型对先进压水堆堆外蒸汽爆炸计算的影响分析

Effect of Corium Jet Fragmentation Model on Ex-vessel Steam Explosion Calculation for Advanced PWR

在堆外蒸汽爆炸计算中,液柱碎化模型影响着熔融物液滴生成速率、液滴直径、液滴分布、液滴凝固和气泡比例等粗混合参数和现象,从而影响了蒸汽爆炸的冲击载荷。本文基于MC3D V3.8程序,采用不同的液柱碎化模型(CONST模型和KHF模型)对先进压水堆堆外蒸汽爆炸进行计算分析,探讨了CONST和KHF模型对蒸汽爆炸计算的影响。结果表明,两种模型计算的粗混合状态类似;在熔融物触底时刻,爆炸性准则几乎相同,此时触发爆炸得到的冲击载荷差别很小,表明该时刻触发爆炸时不同液柱碎化模型对爆炸冲击计算的影响较小;在本文所定义的工况下,先进压水堆堆坑墙体承受的最高压力约为20 MPa,最大冲量小于0.2 MPa·s。

In the ex-vessel steam explosion calculation,the corium jet fragmentation model affects the premixing parameters and phenomena such as generation rate and size of corium drops,the distribution of corium drops,corium drop solidification,void fraction and so on,and then has influence on the strength of steam explosion.Different corium jet fragmentation models（CONST model and KHF model）were used to calculate the ex-vessel steam explosion for advanced PWR based on MC3DV3.8code in order to discuss the effect of corium jet fragmentation model on ex-vessel steam explosion calculation.It is shown that these two models give similar premixing conditions.At the time of melt bottom contact,explosion criteria of these two models are almost the same,so the strength of explosion triggering has a little difference,which indicates that these two models have a little influence on steam explosion calculation if the time of corium bottom contact is chosen as triggering time for advanced PWR.On the defined conditionfor advanced PWR,the maximum pressure near cavity wall is 20 MPa in approximation and the maximum impulse on cavity wall is smaller than 0.2 MPa·s.