反应堆压力容器下腔室交混特性的数值模拟方法研究

Investigation of Numerical Simulation Method on Mixing Characteristic in Lower Plenum of Reactor Pressure Vessel

摘要: 反应堆冷却剂系统蒸汽管道发生破口事故后，硼溶液在反应堆压力容器下腔室的对流交混特性对于反应堆安全分析及事故后缓解与抑制策略制定均有重要作用。本文基于实验结果分析了反应堆压力容器下腔室的交混特性及浓度扩散过程，采用数值模拟方法结合实验数据比较了几种主要模型计算结果的准确性与可靠性。分析结果表明，压力容器下腔室的交混特性呈现出外围扩散特征，温度梯度法与组分输运模型具备描述浓度梯度扩散过程的能力，但在细节分布上仍存在进一步改善与优化的空间。

Abstract: When main steam line break accident occurs in the reactor coolant system, the convection and mixing characteristics of borated water have a great influence on the establishment of reactor safety analysis and mitigation strategies. In this paper, the mixing characteristics and diffusion process of coolant in the lower plenum were discussed based on experimental results. Several prediction models were compared with experimental data to verify the accuracy and reliability. The analytical results show that coolant mixing in the lower plenum tends to have the periphery diffusion process. The temperature gradient model and species transport model both have the ability to predict coolant mixing phenomena, but there shall be a further improvement and optimization in detail for both models.