【摘要】 研究堆芯熔融物对压力容器壁面的动态烧蚀,对于反应堆冷却剂严重丧失事故(Loss of coolant accident,LOCA)后果的预测以及缓解方案的设计具有重要意义。本文以AP600为研究对象,在假设冷却剂全部丧失事故工况下,采用堆芯熔融物两层结构模型,计算熔池对壁面的加热;建立压力容器壁面的非稳态二维传热模型,并考虑安全壳水池对压力容器外侧的冷却,采用移动边界模型模拟烧蚀引起壁面局部厚度变薄;计算了堆芯熔融物坍塌后15 000 s范围内,压力容器下封头壁面温度和厚度的变化。更多还原

【Abstract】 Background: The study on the transient ablation of the pressure vessel wall,acted by the detained melt core,is very important for damage prediction after occurrence of serious loss of coolant accident(LOCA),and design of accident mitigation scheme.Purpose: This paper attempts to study the ablation process of downward part of pressure vessel of AP600,in condition of losing all coolant.Methods: A two-layer of melt material model was used to simulate the structure of melt core,and the heat flux on the vessel wall was computed.The unsteady 2-D heat conduction model was developed for the downward part of pressure vessel,and water boiling in containment was considered as cooling of outer wall.A moving boundary model was used to simulate the decreasing wall thickness on some point in the ablation process.The variation of wall temperature and thickness with time,from occurrence of the accident,till 3 000s after the accident,was computed in detail.Results and Conclusion: Simulation results shows that heat flux from the molten UO2 on the vessel wall grows up with increasing inclination angle,and heat flux from the molten metal is a little small.Temperature on internal wall grows up rapidly with time,which causes the ablation firstly appearing at interface of the two molten layers,and the ablation zone tends to deepen and widen after that.The heat balance between molten material,vessel wall and containment pool will come 9 000s after occurrence of accident,and temperature and ablation zone would not change after 9 000s.更多还原