Heat pipe cooled reactors, which use heat pipes rather than fluid flow for passive cooling, are an excellent candidate for micro nuclear power sources. Heat pipes provide excellent built-in redundancy and safety margin. However, a heat pipe failure is quite likely over the reactor lifetime, which is one of the essential design basis accidents in the reactor design. This work analyzes heat pipe failure accidents to investigate the system transient performance and the response of a heat pipe cooled reactor. Single heat pipe failure and cascading heat pipe failure are simulated and analyzed by establishing a transient analysis code, including a point reactor kinetics model, a core thermal-mechanical model, and a heat pipe model. The simulation shows that in the single heat pipe failure accident, the peak monolith temperature at the failed channel increases and is only 8 K lower than the fuel center temperature. In the cascading heat pipe failure accident, the temperatures in each channel suddenly increase over a short period and rise to the maximum at 22,900 s as the heat losses increase and the core power decreases. The sensitivity of the external convection for residual heat removal is also analyzed. For small external convection coefficients less than 100 W/m²K, increasing the external convection coefficient significantly reduces the maximum temperatures. By contrast, for external convection coefficient greater than 500 W/m²K, increasing external convection coefficient still reduces the core peak temperature, but the effect is weak.

热管冷却反应堆使用热管而不是流体流进行被动冷却，是微型核动力源的理想选择。热管提供出色的内置冗余和安全裕度。然而，在反应堆的整个寿期内，热管失效的可能性很大，这是反应堆设计中必不可少的设计基准事故之一。这项工作分析了热管故障事故，以研究系统瞬态性能和热管冷却反应堆的响应。通过建立瞬态分析程序，包括点反应堆动力学模型、堆芯热力学模型和热管模型，对单热管失效和级联热管失效进行了模拟分析。仿真表明，在单热管失效事故中，故障通道处的峰值整体温度增加，仅比燃料中心温度低 8 K。在级联热管失效事故中，随着热损失的增加和核心功率的降低，每个通道的温度在短时间内突然升高，并在22,900 s时达到最大值。还分析了外部对流去除余热的敏感性。对于小于 100 W/m 的小外部对流系数² K，增加外部对流系数会显着降低最高温度。相比之下，当外部对流系数大于500 W/m ² K时，增加外部对流系数仍会降低核心峰值温度，但效果较弱。