Journal of Nuclear Fuel Cycle and Waste Technology

This study investigates the design and thermal optimization of a microwave reactor crucible system developed for treating radioactive carbon-bearing spent activated carbon. To enhance thermal efficiency and uniformity, six technical improvements were examined: optimized insulation placement, integration of internal heating elements, installation of a stainless steel central reflector, partial replacement of quartz with SUS 304, operation under vacuum (100–300 Torr), and crucible rotation. Each parameter was systematically tested under controlled experimental conditions, with performance evaluated by heating rate, power consumption, and thermal uniformity. The results showed that insulation on the crucible's outer wall provided the highest energy retention, while the central reflector most effectively improved heating uniformity. Partial use of SUS 304 reduced crucible manufacturing costs by over 50% and enhanced mechanical durability. Vacuum conditions marginally suppressed convective heat loss, and crucible rotation minimized local overheating. The integrated strategy yielded a 10–30% improvement in thermal efficiency, demonstrating its practical value in high-temperature microwave applications. This study proposes a scalable framework that may be applied to a wide range of high-temperature microwave systems, especially in the field of radioactive waste treatment.

Keywords

Radioactive spent activated carbon, Microwave heating, Crucible design optimization, Insulation, Reflector, Heating element