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Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori
no journal, ,
The microwave heating denitration method is used in the spent fuel reprocessing process of the nuclear fuel cycle. Since the microwave heating method is accompanied by a transient boiling phenomenon, it is necessary to grasp the operating conditions and to clarify the mechanism of flashing and spilling in order to avoid it. In this study, by assuming the flashing model for the purpose of the clarification of the flashing mechanism by microwave heating, the flashing mechanism of instantaneous generation and growth is considered by calculating the generation frequency and volume of bubble from the visualization result at flushing. The mechanism of flashing phenomenon during microwave heating is thought that the significant flushing phenomenon occurs by the process that a large amount of nanobubbles are generated at a solid-fluid interface in a overheated liquid phase, the bubble group grows exponentially and collapses, and its internal pressure releases.
Kobayashi, Shohei*; Abe, Yutaka*; Kaneko, Akiko*; Fujiwara, Kota*; Futsuta, Akihiro*; Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori
no journal, ,
The microwave heating denitration method is used in the nuclear fuel cycle. To clarify the mechanism of flashing phenomena during microwave heating, it was focused on the frequency of bubble nucleation in heterogeneous nucleation and considered the bubbles generated in the solution. From the visualization observation results, it was verified that a new bubble was generated below the single bubble. The bubbles generated at the gas-liquid interface are considered to be caused by heterogeneous nucleation. Moreover, the calculation results revealed that bubbles were generated at a large contact angle. It is suggested that many bubbles are generated at the gas-liquid interface, and many bubbles generated by heterogeneous nucleation in the superheated liquid phase influence the generation of flashing.