Study on flushing phenomena by microwave heating

Yamaki, Tatsunori*; Kaneko, Akiko*; Abe, Yutaka*; Segawa, Tomoomi ; Kawaguchi, Koichi  ; Yamada, Yoshikazu ; Suzuki, Masahiro ; Fujii, Kanichi*

To use recovered uranium and plutonium as raw material of nuclear fuel, reprocessing solution (uranium and plutonium mixed nitrate solution) of the spent nuclear fuel is converted to uranium and plutonium mixed oxide (MOX) powder. Microwave heating direct denitration method is one of such methods to convert nitrate solution to MOX powder. The cylindrical denitration vessel can be expected to realize high-speed and high-capacity processing against traditional shallow vessel. Flushing and overflow phenomena of solution have been confirmed in cylindrical vessel. The research was conducted in order to clarify mechanism of the flushing and overflow phenomena during microwave heating. It was found that there was tendency of flushing in the case of short vessel diameter and high initial water level when magnetron power was constant. It was confirmed that the liquid temperature just before flushing was superheat.