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Arai, Takahiro*; Ito, Daiyu*; Hirasawa, Izumi*; Miyazaki, Yasunori; Takeuchi, Masayuki
Chemical Engineering & Technology, 41(6), p.1199 - 1204, 2018/06
Times Cited Count：4 Percentile：14.16(Engineering, Chemical)In reprocessing process, spent nuclear fuel is dissolved by HNO
. Mo and Zr in the acidic solution react to form zirconium molybdate hydrate (ZMH). ZMH adheres to the inner-surface of reprocessing equipment, giving a great influence on stable operation. Conventional anti-encrustation is achieved by cleaning the surface of the reprocessing equipment by high pressure water and dissolving wall deposits by acid or alkaline solution. However, the former increases radioactive waste volume, and the latter contributes to corrosion of the metal surface. In this study, encrustation mechanism of ZMH crystal was investigated based on the deposited mass on the solid surface. Observing the deposition process, it was clarified that ZMH fine crystal growth is accelerated and agglomerated, followed by the rapid deposition. Total deposited mass decreased not only by lowering initial ratio of Mo and Zr concentration under the range of 1.0 
Mo/Zr 2.0, but also by lowering HNO concentration.
Takeuchi, Masayuki; Yano, Kimihiko; Shibata, Atsuhiro; Sambommatsu, Yuji*; Nakamura, Kazuhito*; Chikazawa, Takahiro*; Hirasawa, Izumi*
Journal of Nuclear Science and Technology, 53(4), p.521 - 528, 2016/04
Times Cited Count：3 Percentile：25.07(Nuclear Science & Technology)Nakahara, Masaumi; Nomura, Kazunori; Washiya, Tadahiro; Chikazawa, Takahiro*; Hirasawa, Izumi*
Journal of Nuclear Science and Technology, 48(3), p.322 - 329, 2011/03
Times Cited Count：8 Percentile：50.73(Nuclear Science & Technology)The purification behavior of uranyl nitrate hexahydrate was investigated to evaluate the decontamination performance of liquid and solid impurities using a dissolver solution of mixed oxide fuel in batch experiments by the sweating and the melt filtration processes. Liquid impurities such as Eu were effectively removed by the sweating method, but solid impurities such as Pu, Cs and Ba were affected a little in the batch experiments. On the other hand, the decontamination factor of Ba increased with 0.45 and 5.0 
m filters in the melt filtration process. Although the decontamination factors of Pu and Cs did not change with 5.0 m filter, it increased approximately two-fold with 0.45 m filter. The particle size of Cs
Pu(NO)
is a little small and might pass through the 5.0 m filter in the melt filtration process.
Nakahara, Masaumi; Nomura, Kazunori; Washiya, Tadahiro; Chikazawa, Takahiro*; Hirasawa, Izumi*
Radiochimica Acta, 98(6), p.315 - 320, 2010/06
Times Cited Count：7 Percentile：42.89(Chemistry, Inorganic & Nuclear)In order to examine the decontamination behavior of the Pu and fission products in the U crystallization process, experiments were carried out using mixed oxide fuel dissolver solution. It is confirmed that Eu was decontaminated by washing the uranyl nitrate hexahydrate crystals. However, the decontamination factors of Ba and Cs were low because they precipitated as Ba(NO) and CsPu(NO) after the U crystallization, respectively. The decontamination factor of Cs tends to decrease with increasing HNO and Pu concentrations in the mother liquor because of the generation of CsPu(NO).
Nakahara, Masaumi; Nomura, Kazunori; Washiya, Tadahiro; Chikazawa, Takahiro*; Hirasawa, Izumi*
Journal of Alloys and Compounds, 489(2), p.659 - 662, 2010/01
Times Cited Count：2 Percentile：18.44(Chemistry, Physical)Characterization of Cs and Pu(IV) nitrate complex was examined to separation from the UNH crystal. This complex is obtained as a precipitate by mixing dissolver solution of MOX fuel and CsNO solution, which was identified to dicesium tetravalent plutonium hexanitrate, CsPu(NO) by concentration analysis and XRD. The precipitate has a tendency to be generated at high HNO condition. Thermal analysis shows that the precipitate is stable below 245 
C, and a weight loss of about 10.29% is observed at 245 C. This result corresponds to the decomposition of CsPu(NO) to CsPuO(NO)
. According to these properties, the UNH crystal can be melted at 60 C to 100 C, and separated from the Pu(IV) and Cs complex by a filtration. A new technology of crystal purification method aimed at higher decontamination of UNH crystal in the U crystallization process is proposed.
Yano, Kimihiko; Nakahara, Masaumi; Nakamura, Masahiro; Shibata, Atsuhiro; Nomura, Kazunori; Nakamura, Kazuhito*; Tayama, Toshimitsu; Washiya, Tadahiro; Chikazawa, Takahiro*; Kikuchi, Toshiaki*; et al.
Proceedings of International Conference on Advanced Nuclear Fuel Cycle; Sustainable Options & Industrial Perspectives (Global 2009) (CD-ROM), p.143 - 150, 2009/09
Koizumi, Masumichi; Honda, Yutaka*; Yumoto, Ryozo; ; ; ; Hirasawa, Masayoshi; Yagi, Takao
PNC TN841 79-38, 250 Pages, 1979/06
no abstracts in English
Nakahara, Masaumi; Nomura, Kazunori; Washiya, Tadahiro; Chikazawa, Takahiro*; Hirasawa, Izumi*
no journal, ,
For developing the crystal purification for UNH crystal obtained from crystallization process, crystal purification experiments were conducted with dissolver solution of MOX fuel. Sweating experiments were carried out for purification of liquid impurity, melting operation was attempted for separation of solid impurity. Basic data about development of the crystal purification process were obtained in our experiments.
Hirasawa, Izumi*; Chikazawa, Takahiro*; Washiya, Tadahiro
no journal, ,
no abstracts in English
Washiya, Tadahiro; Yano, Kimihiko; Chikazawa, Takahiro*; Hirasawa, Izumi*
no journal, ,
no abstracts in English
Washiya, Tadahiro; Chikazawa, Takahiro*; Hirasawa, Izumi*
no journal, ,
no abstracts in English
Nakahara, Masaumi; Nomura, Kazunori; Washiya, Tadahiro; Chikazawa, Takahiro*; Hirasawa, Izumi*
no journal, ,
Concerning the purification technology of UNH crystallization, crystallization purification experiments was carried out with the dissolver solution of irradiated fast reactor core fuel. Sweating operation was attempted for separation of liquid impurities from the UNH crystal, and melt filtration operation was applied to decontamination of solid impurities to U in the crystal. Basic data was obtained for the research and development on crystal purification in the crystallization process.
Hirasawa, Izumi*; Chikazawa, Takahiro*; Washiya, Tadahiro
no journal, ,
no abstracts in English
Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.
no journal, ,
no abstracts in English
Hyodo, Toshio*; Fukaya, Yuki; Takahashi, Toshio*; Fujinami, Masanori*; Wada, Ken*; Mochizuki, Izumi*; Shidara, Tetsuo*; Kawasuso, Atsuo; Maekawa, Masaki; Shirasawa, Tetsuro*
no journal, ,
no abstracts in English
Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; Furukawa, Kazuro*; et al.
no journal, ,
no abstracts in English
Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.
no journal, ,
no abstracts in English
Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.
no journal, ,
no abstracts in English
Wada, Ken*; Mochizuki, Izumi*; Hyodo, Toshio*; Kosuge, Takashi*; Saito, Yuki*; Nigorikawa, Kazuyuki*; Shidara, Tetsuo*; Osawa, Satoshi*; Ikeda, Mitsuo*; Shirakawa, Akihiro*; et al.
no journal, ,
no abstracts in English
Takeuchi, Masayuki; Koizumi, Tsutomu; Ikeda, Shoki*; Cho, R.*; Hirasawa, Izumi*
no journal, ,
no abstracts in English
