Development and Application of Cooling Characteristic Analysis Code for Molten Debris Bed
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摘要: 为分析压水堆严重事故后期形成碎片床的冷却特性，开发了熔融物碎片床冷却特性分析程序。以一维六方程的两相流模型为基础，应用多孔介质流动沸腾传热模型描述碎片床内两相流动传热物理过程，采用控制容积积分法、半隐式、一阶迎风格式对方程进行离散、求解。应用TUTU、COOLOCE、STYX实验结果，从两相流动及干涸热流密度（DHF）2个方面对模型进行验证，发现Hu&Theofanous模型和Reed模型对于粒径相对较大的碎片床的两相流动预测结果较好，而Lipinski模型对小颗粒碎片床的低压DHF的预测精度较高。利用程序对压水堆严重事故条件下熔融物碎片床的冷却能力进行预测，在1 MW/m3颗粒释热率、顶部水池淹没条件下，碎片床可被冷却高度为0.56 m；采用自然循环驱动底部注水冷却方式，碎片床可被冷却高度升至0.85 m。
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关键词:
- 严重事故 /
- 碎片床 /
- 多孔介质 /
- 沸腾传热 /
- 干涸热流密度（DHF）
Abstract: To analyze the cooling characteristics of debris bed formed in the late stage of severe accident in pressurized water reactor, an analysis code for molten debris bed cooling was developed. Based on the one-dimensional six-equation two-phase flow model, the physical process of two-phase flow and heat transfer in the debris bed was described by using the porous medium flow boiling heat transfer model, and the equations were discretized and solved by using the controlled volume integral method, semi-implicit method and first-order upwind scheme. The results of TUTU, COOLOCE and STYX experiments were used to validate the model from aspects: two-phase flow and dry-out heat flux (DHF). It was found that Hu&Theofanous model and Reed model had better prediction results for the two-phase flow of debris bed with relatively large particle size, while Lipinski model had higher prediction accuracy for the low-pressure DHF of small particle debris bed. The cooling capacity of molten debris bed in severe accident of PWR was predicted by the code. At a particle heat release rate of 1 MW/m3, the cooling height of debris bed was 0.56 m under top-flooding condition; and the height increased to 0.85 m by using bottom-flooding driven by natural circulation.-
Key words:
- Severe accident /
- Debris bed /
- Porous media /
- Boiling heat transfer /
- Dry-out heat flux (DHF)
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图 5 程序计算结果同TUTU实验结果对比情况（ε=0.39，Dp=3.18 mm，H=0.46 m）
Figure 5. Comparison between Calculated Results and TUTU Experimental Results (ε=0.39, Dp=3.18 mm, H=0.46 m)
图 6 程序计算结果同TUTU实验结果对比情况（ε=0.38，Dp=6.35 mm，H=0.46 m）
Figure 6. Comparison between Calculated Results and TUTU Experimental Results (ε=0.38, Dp=6.35 mm, H=0.46 m)
图 7 程序计算结果同COOLOCE实验结果对比情况（ε=0.38，Dp=0.9 mm，H=0.27 m）
Figure 7. Comparison between Calculated Results and COOLOCE Experimental Results (ε=0.38, Dp=0.9 mm, H=0.27 m)
图 8 程序计算结果同STYX实验结果对比情况（ε=0.37，Dp=0.8 mm，H=0.27 m）
Figure 8. Comparison between Calculated Results and STYX Experimental Results (ε=0.37, Dp=0.8 mm, H=0.27 m)
图 10 顶部水池淹没冷却条件下碎片床高度达到干涸时颗粒温度随时间变化情况
Figure 10. Variation of Particle Temperature with Time When the Height of Debris Bed Meets Dry-out under Top-flooding Condition
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