冷却剂锂内空隙对空间堆停堆及启动过程传热影响

Effect of Void in Lithium Coolant on Heat Transfer of Space Reactor Cooldown and Startup Processes

为分析液态金属冷却空间堆在轨再启动的安全特性,基于单一(固/液)单元数值求解方法分析研究了冷却剂收缩空隙对空间堆冷却剂锂凝固及熔化过程传热的影响。结果表明,壁面空隙的形成与存在减小了固液界面的熔化速率,而中心空隙对熔化及凝固过程的影响不大。同时,壁面空隙的存在,使得在熔化过程中壁面温度有一持续的升高,对于锂冷却剂,壁面温度远小于空间堆系统结构材料PWC-11的熔化温度,使得在空间堆系统启动和再启动过程基本不会形成热斑。

To analyze the safety characteristics of liquid metal cooled space reactor restarting in orbit, the effects of shrinkage void on both lithium coolant freezing and melting processes were investigated using a numerical scheme, which was based on a single （solid/liquid） cell approach. Results show that void formation at the wall appre-ciably reduces the solid-liquid interface melting velocity, and the center void has little effect on the freezing and melting processes. Meanwhile, the wall void causes a substantial rise in the wall temperature during melting process. H o w e v e r, in the case of Li, the maximum wall temperature is much lower than the melting temperature of P W C - 11, which is used as the structure material in the space reactor system. Hence, it is con-cluded that a formation of hot spots is unlikely during the startup or restarting of the space reactor system.