Space nuclear reactor power (SNRP) using a gas-cooled reactor (GCR) and a closed Brayton cycle (CBC) is the ideal choice for future high-power space missions. To investigate the safety characteristics and develop the control strategies for gas-cooled SNRP, transient models for GCR, energy conversion unit, pipes, heat exchangers, pump and heat pipe radiator are established and a system analysis code is developed in this paper. Then, analyses of several operation conditions are performed using this code. In full-power steady-state operation, the core hot spot of 1293 K occurs near the upper part of the core. If 0.4 $ reactivity is introduced into the core, the maximum temperature that the fuel can reach is 2059 K, which is 914 K lower than the fuel melting point. The system finally has the ability to achieve a new steady-state with a higher reactor power. When the GCR is shut down in an emergency, the residual heat of the reactor can be removed through the conduction of the core and radiation heat transfer. The results indicate that the designed GCR is inherently safe owing to its negative reactivity feedback and passive decay heat removal. This paper may provide valuable references for safety design and analysis of the gas-cooled SNRP coupled with CBC.

使用气冷反应堆 (GCR) 和闭合布雷顿循环 (CBC) 的空间核反应堆功率 (SNRP) 是未来高功率空间任务的理想选择。为了研究气冷SNRP的安全特性并制定控制策略，本文建立了GCR、能量转换单元、管道、热交换器、泵和热管散热器的瞬态模型，并开发了系统分析代码。然后，使用此代码执行几个操作条件的分析。在全功率稳态操作中，1293 K 的核心热点出现在核心上部附近。如果将0.4$反应性引入堆芯，燃料所能达到的最高温度为2059 K，比燃料熔点低914 K。该系统最终能够以更高的反应堆功率实现新的稳态。当GCR紧急停堆时，反应堆的余热可以通过堆芯传导和辐射传热的方式带走。结果表明，设计的 GCR 由于其负反应性反馈和被动衰变热去除而具有本质安全性。本文可为气冷SNRP与CBC耦合的安全设计和分析提供有价值的参考。