熔融物堆芯冷却滞留特性研究

以模块式小型堆ACP100为分析对象，建立MELCOR程序严重事故分析模型，分析了堆芯衰变热依次经过吊篮、压力容器壁面然后进入堆腔注水系统（CIS）的传热行为。采用燃料棒失效模型评价燃料组件坍塌行为，并通过ANSYS程序蠕变断裂模型评价堆芯下板失效行为。分析结果表明，严重事故后堆芯中心燃料组件坍塌形成堆芯熔融池，堆芯周围燃料组件保持完整结构状态，堆芯下板支撑堆芯熔融池和未坍塌的燃料组件且未发生蠕变断裂失效；CIS冷却压力容器外壁面并导出堆芯衰变热，最终实现熔融物堆芯滞留，避免下封头内形成熔融池。 

Research on Debris In-Core Cooling and Retention Characteristics

The severe accident analysis model of the small modular reactor ACP100 is built using MELCOR code, and the core heat removed process through the barrel and wall of reactor pressure vessel (RPV) is analyzed by the cavity injection system (CIS). The collapse behavior of the fuel assemblies is estimated by the fuel rod degradation model, and the failure behavior of the lower core plate is estimated by ANSYS program. The results show that the fuel assemblies in the core center melt and collapse to form the core melting pool, while the structure of the fuel assemblies surrounding the core melting pool remains intact, and the core lower plate supports the core melting pool and un-collapsed fuel assemblies all the time, and no creep rupture phenomenon occurs; the core heat can be removed by CIS and the debris in-vessel retention successfully avoids the formation of molten pool in the lower head.