堆芯熔融物在下腔室内冷却模型研究及缓解集热效应的对策

Study on Cooling Model for Debris in Lower Plenum and Countermeasures for Prevention of Focusing Effect

从能量守恒方程出发,选取较为现实的实验公式和经验公式,建立了一个完整的堆芯熔融物在下腔室内冷却的计算模型。为了验证本模型的合理性,以AP600和AP1000反应堆为例进行了计算分析,并将计算结果与文献例题进行了比较。重点分析了堆芯熔融物单位体积释热量以及集热效应对堆芯熔融物冷却的影响。针对集热效应,提出了将压力容器下封头的半球形状改为旋转抛物线形状的对策。结果表明,下封头形状的改变能显著改变堆芯熔融物的热流密度分布,缓解集热效应。

From the basic energy conservation equations and experimental or empirical correlations, an intact model is constructed for the thermal calculation of the core debris in the lower plenum. For verification of this model, the results of two calculations for AP600 and AP 1000 plants are compared with those presented in relevant literature. The analysis highlights on the impact of the decay heat power density and the focusing effect. In order to mitigate the focusing effect, it is proposed in this paper to change the lower head profile from hemisphere to parabola. The results show that this change of lower head profile can change the heat flux distribution of the debris, and mitigate the focusing effect.