Design, fabrication, and comparative analysis of prototype high-temperature heat pipes charged with sodium for heat pipe cooled reactor NUSTER-100

Heat pipe cooled reactors utilize high-temperature heat pipes for core heat removal, offering advantages such as simple structures, no moving parts, passiveness, etc. However, the fabrication and thermal testing of high-temperature heat pipes designed for reactor applications remain limited. This study aims to develop and evaluate high-temperature heat pipes tailored to reactor requirements. Ten high-temperature heat pipes with varying structural designs were fabricated and tested. The results indicate that the maximum thermal load capacity of these heat pipes reaches 10.1 kW, meeting reactor specifications. In terms of the wick, with a smaller pore size at the boundary, the heat transfer performance can be improved. A high-temperature heat pipe with concentric gaps demonstrated a 17.4 % higher heat transfer power than those with eccentric gaps, while using a support block instead of a support ring resulted in a 24.2 % decrease in thermal power. Although a bend with a 30°angle and a 300 mm radius minimally impacted the isothermal performance of high-temperature heat pipe (△T ≤ 4.2 °C), it led to earlier onset of overheating. Experimental validation of high-temperature heat pipe failures, including oxidation and rupture, was conducted. These findings establish a foundation for further development of high-temperature heat pipes and their integration into heat pipe cooled reactors.