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Fujita, Shunya*; Abe, Yutaka*; Kaneko, Akiko*; Yuasa, Tomohisa*; Segawa, Tomoomi; Kato, Yoshiyuki; Kawaguchi, Koichi; Ishii, Katsunori
Proceedings of 11th Korea-Japan Symposium on Nuclear Thermal Hydraulics and Safety (NTHAS-11) (Internet), 7 Pages, 2018/11
Mixed uranium oxide and plutonium oxide powder is produced from uranyl nitrate and plutonium nitrate mixed solution by the microwave heating denitration method in the spent fuel reprocessing process. Since the microwave heating method is accompanied by a boiling phenomenon, it is necessary to fully grasp the operating conditions in order to avoid flashing and spilling in the mass production of denitrification technology for the future. In this research, it was clarified that the heat transfer coefficient became lower as the dielectric constant increased. The dominant factor of the blowing up phenomena is supposed to be generation of the innumerable bubble rather than bubble's growth.
Kobayashi, Shohei*; Abe, Yutaka*; Kaneko, Akiko*; Fujiwara, Kota*; Futsuta, Akihiro*; Segawa, Tomoomi; Kawaguchi, Koichi; Ishii, Katsunori
no journal, ,
In the reprocessing process in the nuclear fuel cycle, a solution of plutonium nitrate and uranyl nitrate is converted into a mixed oxide by microwave heating denitration method. The objective of this study is to clarify the mechanism of the flashing phenomenon and to clarify the effect of the microwave heating characteristics of a high dielectric constant solution on the flashing phenomenon. Microwave heating experiments were conducted using KCl aqueous solution, which is the high dielectric constant solution simulating the reprocessing solution. It was clarified that the growth rate of bubbles in the KCl aqueous solution decreased with the time of microwave heating compared with distilled water. It is thought that in the KCl aqueous solution, the heating efficiency at the center of the solution is lower than that in the surroundings, and the growth rate of bubbles is reduced so that the flashing phenomenon does not easily occur in the high dielectric constant solution.