Evaluating heat pipe technologies for nuclear cooling: from terrestrial spent fuel pools to space-based reactors

Abstract This paper investigates the feasibility and performance of heat pipe technology for Spent Fuel Pool cooling in nuclear power plants. While traditional single-phase indirect cooling via a separated cooling circuit enhances safety by preventing potential pool drainage, it is limited by lower heat transfer rates. Two-phase heat transfer offers significantly higher capacity via latent heat but introduces complexities such as “geysering” and flow instabilities. This study describes amongst the technical basics of heat pipes a systematic design cycle – incorporating hand calculations, 1 D system modeling, and experimental validation ranging from small-scale tests to full-scale loop heat pipe setups – to design reliable thermosiphon and loop heat pipe configurations. Results indicate that while thermosiphon heat pipes encounter stability issues at the low temperature differences typical of terrestrial Spent Fuel Pool applications, loop heat pipes provide much more stable and controllable heat removal. The paper concludes that while heat pipes face regulatory and technical restrictions for low-temperature nuclear Spent Fuel Pool cooling applications, they are exceptionally well-suited for extraterrestrial reactor cooling. In space environments, higher temperature gradients stabilize heat pipe behavior, and the technology provides inherent redundancy against micro-meteorite strikes.