赵鑫海,陈鹏,贺东钰,厉井钢,杨盛智

• 1:中广核研究院有限公司

摘要(Abstract)：

污垢材料在堆芯中迁移和沉积，在包壳表面附着有可能引起传热恶化甚至出现燃料棒局部熔化现象。国内自主开发的压水堆燃料棒分析程序BIRCH暂未考虑潜热，保守假定芯块温度超过熔点3 K完全熔化，导致计算得到的芯块熔化份额非常接近放射物质释放超标验收准则，且存在陡边效应。为解决程序计算过于保守问题，本文采用固定网格等效热容法开发了燃料棒熔化相变导热模型。相比于焓方法，等效热容法仅需对热容进行特殊处理，对整体程序代码改动较小。但传统等效热容法在跨越相变区时易出现数值不稳定性问题，导致计算结果出错。本文首先对等效热容法数值不稳定性产生的原因进行分析，同时基于能量守恒原则建立预测-修正相变求解算法，改进现有等效热容法，并采用不同边界条件解析解、Stefan精确解和焓方法数值解对改进等效热容法进行验证。计算分析结果表明预测-修正相变算法可提升传统等效热容法计算稳定性，且与Stefan精确解数值误差在5%以内，将其应用到污垢传热恶化事故中可提升现有计算结果安全分析裕量。

关键词(KeyWords)： 熔化相变算法;改进等效热容法;BIRCH;陡边效应

Abstract:

Keywords:

基金项目(Foundation): “国家重点研发计划”资助（2019YFB1900702）

作者(Author): 赵鑫海,陈鹏,贺东钰,厉井钢,杨盛智

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