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Murakami, Tsuyoshi*; Hayashi, Hirokazu
Journal of Nuclear Materials, 558, p.153330_1 - 153330_7, 2022/01
Times Cited Count:0 Percentile:0.01(Materials Science, Multidisciplinary)Excess amounts of dissolution agents, CdCl and ZrCl, are required to dissolve transuranium (TRU: Pu and minor actinides) nitrides into LiCl-KCl melts at the chemical dissolution step, which is the first step in the reprocessing of used nitride fuels. We propose an electrochemical process where the remaining Zr and Cd are recovered from the melts to be recycled as dissolution agents for the chemical dissolution step, leaving TRU in the melts. Since the initial concentration ratio of CdCl/ZrCl remaining in the melts would depend on the condition of the chemical dissolution step and would vary during the proposed electrochemical recovery process, electrochemical behaviors of Zr and Cd were investigated in LiCl-KCl melts with various concentration ratios of CdCl/ZrCl at 723 K to confirm the basic feasibility of the proposed process. Potentiostatic electrolysis was performed using a liquid Cd cathode at -1.05 V (vs. Ag/AgCl), which was a more positive potential than the redox potentials of TRU on the liquid Cd electrode. The obtained results showed that the current efficiency for recovering Zr and Cd from the melts was as high as 100% regardless of the CdCl/ZrCl concentration ratio in the melts.
Kato, Tetsuya*; Inoue, Tadashi*; Iwai, Takashi; Arai, Yasuo
Journal of Nuclear Materials, 357(1-3), p.105 - 114, 2006/10
Times Cited Count:107 Percentile:98.82(Materials Science, Multidisciplinary)Electrorefining in the molten LiCl-KCl eutectic salt containing actinides(An) and rare-earths(RE) was conducted to recover up to 10 wt% An into liquid Cd cathode, which is much higher than the solubility of An in liquid Cd at the experimental temperature. In the saturated Cd cathode, An and RE were recovered to form a compound of the PuCd lattice, MCd. The separation factors of RE against Pu were defined as (RE/Pu in the Cd cathode)/(RE/Pu in the salt) and calculated for the saturated Cd alloy including MCd. The separation factors for the Cd cathodes were a little larger than the equilibrium values.
Hayashi, Hirokazu; Minato, Kazuo
Journal of Physics and Chemistry of Solids, 66(2-4), p.422 - 426, 2005/02
Times Cited Count:34 Percentile:75.63(Chemistry, Multidisciplinary)Stability of lanthanide sesquioxides (LnO; Ln=La, Nd, Gd) in LiCl-KCl eutectic melt is studied. Some lanthanide oxides have been pointed out to form oxide chlorides (LnOCl) in the chloride melts, according to the reaction, LnO + 2Cl = 2LnOCl +O. Equilibrium of the reaction for Ln = La, Nd, Gd in LiCl-KCl eutectic melt were studied. Entire LaO and a part of NdO converted to LaOCl and NdOCl respectively, though GdO remained with a trace amount of GdOCl for 2wt % of LnO in LiCl-KCl eutectic melt. The equilibrium depends on the free energies of formation of the solid compounds, LnO and LnOCl, and that of oxide ion (O) in the melt. We derive the chemical potential of the oxide ion from the equilibrium using the reported thermochemical data of LnO and LnOCl.
Shirai, Osamu; Uozumi, Koichi*; Iwai, Takashi; Arai, Yasuo
Journal of Applied Electrochemistry, 34(3), p.323 - 330, 2004/03
Times Cited Count:28 Percentile:52.34(Electrochemistry)The electrode reactions of the Np/Np couple at liquid Cd and Bi electrodes were investigated by cyclic voltammetry at 723, 773 and 823 K in LiCl-KCl eutectic melt. It was found that the diffusion of Np in the salt phase was a rate-determining step in the cathodic reaction when the concentration of NpCl was less than about 1 wt.% and the liquid Cd or Bi phase was not saturated with Np. The redox potentials of the Np/Np couple at liquid Cd electrode at 723, 773 and 823 K were observed more positively than those at Mo electrode by 0.158, 0.140 and 0.126 V, respectively. The potential shift would result from a lowering of activity of Np in Cd phase according to the alloy formation of NpCd at 723 K and NpCd at 773 and 823 K. The redox potentials of the Np/Np couple at liquid Bi electrode at 723, 773 and 823 K were more positive than those at Mo electrode by 0.427, 0.419 and 0.410 V, respectively, which would be attributable to a lowering of activity of Np in Bi phase according to the formation of NpBi.
Shirai, Osamu; Uozumi, Koichi*; Iwai, Takashi; Arai, Yasuo
Journal of Nuclear Science and Technology, 39(Suppl.3), p.745 - 748, 2002/11
no abstracts in English
Iizuka, Masatoshi*; Uozumi, Koichi*; Inoue, Tadashi*; Iwai, Takashi; Shirai, Osamu; Arai, Yasuo
Journal of Nuclear Materials, 299(1), p.32 - 42, 2001/10
Times Cited Count:76 Percentile:97.53(Materials Science, Multidisciplinary)no abstracts in English
Shirai, Osamu; Iizuka, Masatoshi*; Iwai, Takashi; Arai, Yasuo
Journal of Applied Electrochemistry, 31(9), p.1055 - 1060, 2001/09
Times Cited Count:22 Percentile:47.09(Electrochemistry)no abstracts in English
Shirai, Osamu; Iizuka, Masatoshi*; Iwai, Takashi; Suzuki, Yasufumi; Arai, Yasuo
Journal of Nuclear Science and Technology, 37(8), p.676 - 681, 2000/08
no abstracts in English
Shirai, Osamu; Iwai, Takashi; Shiozawa, Kenichi; Suzuki, Yasufumi; Sakamura, Y.*; Inoue, Tadashi*
Journal of Nuclear Materials, 277(2-3), p.226 - 230, 2000/02
Times Cited Count:24 Percentile:80.77(Materials Science, Multidisciplinary)no abstracts in English
Iizuka, Masatoshi*; Uozumi, Koichi*; Inoue, Tadashi*; Iwai, Takashi; Shirai, Osamu; Arai, Yasuo
Proceedings of 6th International Exchange Meeting on Actinide and Fission Product Partitioning and Transmutation (CD-ROM), p.327 - 341, 2000/00
no abstracts in English
Sakamura, Y.*; Inoue, Tadashi*; Shirai, Osamu; Iwai, Takashi; Arai, Yasuo; Suzuki, Yasufumi
Proc. of the Int. Conf. on Future Nuclear Systems (GLOBAL'99)(CD-ROM), 8 Pages, 1999/00
no abstracts in English
; H.Shimotake*
New Mater.New Processes, 2, p.283 - 288, 1983/00
no abstracts in English
; *
Yoyuen, 23(2), p.117 - 134, 1980/00
no abstracts in English
;
Nihon Genshiryoku Gakkai-Shi, 5(3), p.210 - 218, 1963/00
no abstracts in English
Murakami, Tsuyoshi*; Iizuka, Masatoshi*; Hayashi, Hirokazu
no journal, ,
no abstracts in English
Ibe, Junya*; Aso, Megumi*; Takahatake, Yoko; Watanabe, So; Watanabe, Masayuki; Matsuura, Haruaki*
no journal, ,
Since waste salt generated from pyro-reprocessing test which contains uranium can easily capture moisture and corrode equipment, further treatment technology for decontamination. Oxides are added as oxygen donor in the melts, and then uranium is separated from the salt as precipitates. In the next step, melt bath components are evaporated by a vacuum distillation. First, LiCl-KCl eutectic and NaCl-2CsCl salts were used as melt baths, lithium oxide was used as a precipitant, and cerium chloride was used as uranium surrogate for testing the precipitation process. Next, a distillation line has been constructed and the best condition for distillation has been searched. Amount of the precipitates increased with increasing the amount of oxide, and recovery ratio of cerium must potentially depend on solubility of oxychloride into the bath salts. It is considered that oxychloride was formed by the similarity in EXAFS oscillation and X-ray diffraction patterns.