意外事故下控制鼓和安全鼓对空间核反应堆反应性影响研究

Research on the Effects of Control Drum and Safety Drum on the Reactivity of Space Nuclear Reactors in Accidents

摘要: 空间核反应堆电源是未来太空探索能源的必然选择，近几年逐渐成为全球研究的热点。意外事故工况下的临界状况对空间核反应堆的性能和安全至关重要。本文针对TOPAZ-II热离子反应堆，对意外事故工况下反应堆反应性无法满足安全要求的问题，提出了优化方法。研究结果表明：在反射层脱落的事故下，只旋转控制鼓可以使TOPAZ-II处于临界安全状态；在水和湿沙浸入的事故下，keff增长非常快，旋转控制鼓和安全鼓都无法有效降低反应性，反应堆无法达到临界安全状态。针对该问题对控制鼓和安全鼓进行优化。优化的内容为同时改变鼓内含硼组件的厚度和¹⁰B的富集度，计算每次改变下k_eff的值，得到k_eff与含硼组件厚度和10B富集度之间的关系拟合曲线。根据得到的拟合曲线，建立一套满足安全需求的优化方法。该优化方法可为未来空间反应堆设计提供参考价值。

Abstract: Space nuclear reactor power supply is an inevitable choice for future space exploration energy, and has gradually become a global research hotpot in recent years. The critical conditions under accidental conditions are crucial for the performance and safety of space nuclear reactors. Aiming at the TOPAZ-II thermionic reactor, this study presents an optimization method for the problem that the reactor reactivity can not meet the safety requirements under accident conditions. The results show that only rotating control drum can make TOPAZ-II in a critical safety state under the accident of reflector falling off; in the event of water and wet sand immersion, keff grows very fast, neither the rotary control drum nor the safety drum can effectively reduce the reactivity, and the reactor cannot reach a critical safety state. To solve this problem, optimize the control drum and safety drum. The content of optimization is to change the thickness of boron components contained in the drum and the enrichment degree of ¹⁰B at the same time, calculate the k_eff value under each change, and obtain the fitting curve of the relationship between k_eff and the thickness of boron components and the enrichment degree of 10B. According to the fitting curve, establish a set of optimization methods to meet the safety requirements. This optimization method can provide reference value for future space reactor design.