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Yamaki, Tatsunori*; Abe, Yutaka*; Kaneko, Akiko*; Segawa, Tomoomi; Kawaguchi, Koichi; Yamada, Yoshikazu; Fujii, Kanichi*
Journal of Nuclear Science and Technology, 52(2), p.241 - 250, 2015/02
Times Cited Count:3 Percentile:24.31(Nuclear Science & Technology)In the Microwave Heating de-nitration method developed in Japan, a mixed solution of uranyl nitrate and plutonium nitrate recovered from the spent fuel in the reprocessing plant is converted directly to mixed oxide (MH-MOX) powder. This MH-MOX powder is utilized to fabricate MOX fuel with UO powder for FBR. The MH method is accompanied with transient boiling phenomena such as overflow and flushing. Toward high-speed and high-capacity conversion by MH-method in the future, it is required to avoid overflow and flushing and to understand optimal design conditions for design and operation. At the first step for these objectives, basic knowledge of transient boiling phenomena by the MH-method has been acquired with using distilled water. It was observed that generation of singular bubble triggered flushing and distilled water just before flushing was superheated by a temperature 10 degrees centigrade higher than boiling temperature. Based on these results, it is clarified that the occurrence criteria of flushing correlate with absorbed power in the water and released power from the water surface.
Nakajima, Kaoru*; Morita, Yosuke*; Kitayama, Takumi*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Tsujimoto, Masahiko*; Isoda, Shoji*; Fujii, Yoshikazu*; Kimura, Kenji*
Nuclear Instruments and Methods in Physics Research B, 332, p.117 - 121, 2014/08
Times Cited Count:7 Percentile:46.03(Instruments & Instrumentation)Fujii, Hiromitsu*; Hara, Kojiro*; Komine, Masashi*; Ozaki, Takuo; Onuki, Toshihiko; Yamamoto, Yoshikazu*
Journal of Nuclear and Radiochemical Sciences, 6(1), p.115 - 118, 2005/07
We studied the association of a Cu tolerant mycobiont, Tremolecia atrata (rusty-rock lichen) with Cu. T. atrata mycobiont cell aggregates, which grew into a sperical shape, rapidly absorbed Cu into their inner and outer parts. The EDS/SEM study showed that Cu was more highly accumulated in the inner part than the outer part of the aggregates. The XANES study revealed that the Cu absorbed by the T. atrata mycobiont was both monovalent and divalent. These results suggested that the T. atrata mycobiont's high tolerance to Cu is attributable to its ability to store Cu(I) inside the cytoplasm and to adsorb Cu(II) on the cell wall.
Maebara, Sunao; Moriyama, Shinichi; Fujii, Tsuneyuki; Okumura, Yoshikazu
no journal, ,
Maebara, Sunao; Moriyama, Shinichi; Fujii, Tsuneyuki; Okumura, Yoshikazu
no journal, ,
no abstracts in English
Yamaki, Tatsunori*; Kaneko, Akiko*; Abe, Yutaka*; Segawa, Tomoomi; Kawaguchi, Koichi; Yamada, Yoshikazu; Suzuki, Masahiro; Fujii, Kanichi*
no journal, ,
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.