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根据聚变-裂变混合堆概念堆型的燃料区水冷设计,通过FLUENT建模和模拟计算,比较了均匀流量和按燃料单元发热量比例分配流量两种冷却剂布置方案。数值计算结果表明,这两种布置方案中燃料单元之间的导热很小,除燃料单元1中冷却管道外,其余的冷却管道带走的热量几乎等于相应燃料单元的发热量,在用系统分析程序等效建模时,不必重新确定冷却管道的热构件;对后一种布置方案燃料区的最高温度更低,温度分布更均匀,但温度展平效果并不明显。计算了堆外自然循环系统在假设的失水事故(LOCA)中的导热能力。结果表明,如果不采用自然循环系统,停堆后520s发生堆芯熔化;但是如果采用自然循环系统,停堆后1000s,燃料区的最高温度只达到584.4°C,不会发生堆芯熔化。

Optimization of coolant arrangement for fusion-fission hybrid reactor and analysis of ex-core nature circulation

The simulation and numerical computation with FLUENT code are conducted for the fuel zone of fusion-fission hybrid reactor. Two coolant flowing arrangement schemes, uniform flow, and proportional flow based on the gross heat of each fuel cell, are compared for optimization. The results of the numerical computation show that the heat conduction between adjacent fuel cells is weak and the heat is carried away by the coolant in the duct, and it is almost completely equal to the heat produced by corresponding fuel cell except the fuel cell 1. Then the value of heat structure of the coolant duct is the gross heat of each fuel cell that means there is no need to remodel the fuel zone with system analysis program. The fuel zone has lower maximum temperature and more even temperature distribution in the case of proportional flow compared with uniform flow, but the effect of flattening temperature is not obvious. The capacity of heat transfer of ex-core nature circulation in the imaginary LOCA is also evaluated. The results show that the reactor core will be melted within 520s after shut-down without the nature circulation and the maximum temperature in the fuel region will be only elevated to 584.4°C within 1000s after shut-down if with the nature circulation.