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Journal Articles

Extraction chromatography for Am and Cm recovery in engineering scale

Koma, Yoshikazu; Watanabe, So; Sano, Yuichi; Asakura, Toshihide; Morita, Yasuji

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 8 Pages, 2008/05

Journal Articles

Oxygen potentials of transuranium oxides

Otobe, Haruyoshi; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 4 Pages, 2008/05

The oxygen potentials of cubic zirconia containing Pu and americia have been measured by the electromotive force (EMF) method with a zirconia solid-electrolyte. The oxygen potentials of these oxides were reviewed. The phase relations, microstructure, equilibrium state of these oxides were discussed, referring to the isothermal curve of the oxygen potentials. It was found that the oxygen potentials are sensitive to the phase transitions. Moreover, the study on the microstructure around an element incorporated in oxide fuels as well as its phase is necessary to predict the effect of the element on the oxygen potentials of oxide fuels.

Journal Articles

Extraction and flow sheet studies for U and Pu separation by N,N-di(2-ethyl)hexylbutanamide

Ban, Yasutoshi; Hagiya, Hiromichi; Sato, Makoto; Asakura, Toshihide; Morita, Yasuji

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 4 Pages, 2008/05

Since N,N-dialkylamide (monoamide) compounds extract tetravalent and hexavalent actinides, they have been proposed as alternative extractants to TBP. In the present work, numerical calculations for estimating separation performance of N,N-di(2-ethyl)hexyl-butanamide (D2EHBA) for U(VI) and Pu(IV) were carried out. A flow sheet was obtained which separate more than 99.9% of Pu(IV) from U(VI) by adjusting nitric acid concentration. Extraction properties of D2EHBA for macro concentrations of U (0.63-1.22 mol/dm$$^{3}$$(M)) and Pu (6.3 mM) were studied in a batch manner. D2EHBA diluted to 1.5 M by n-dodecane extracted up to 0.8 M of U(VI) without forming precipitation and third phase. Distribution ratios of Pu(IV) were relatively high compared with the ones obtained at tracer concentrations of Pu(IV).

Journal Articles

Thermal conductivities of minor actinide oxides for advanced fuel

Nishi, Tsuyoshi; Ito, Akinori; Takano, Masahide; Akabori, Mitsuo; Arai, Yasuo; Minato, Kazuo

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 6 Pages, 2008/05

The thermal diffusivities of americium oxide and neptunium dioxide were determined by a laser flash method. It was found that the thermal diffusivities of AmO$$_{2-x}$$ and NpO$$_{2}$$ decreased with increasing temperature. It was also found that the decrease in O/Am ratio during the thermal diffusivity measurements under vacuum resulted in a slight decrease in thermal diffusivity of AmO$$_{2-x}$$. The thermal conductivities of AmO$$_{2-x}$$ and NpO$$_{2}$$ were evaluated from the measured thermal diffusivities, heat capacities and bulk densities. The thermal conductivity of AmO$$_{2-x}$$ was smaller than those of the literature values of UO$$_{2}$$ and PuO$$_{2}$$. On the other hand, the thermal conductivity of NpO$$_{2}$$ from 873 to 1473 K lay between those of UO$$_{2}$$ and PuO$$_{2}$$. The thermal conductivities of AmO$$_{2-x}$$ and NpO$$_{2}$$ decreased with increasing temperature in the temperature range investigated.

Journal Articles

Ingot formation using uranium dendrites recovered by electrolysis in LiCl-KCl-PuCl$$_{3}$$-UCl$$_{3}$$ melt

Fukushima, Mineo; Nakayoshi, Akira; Kitawaki, Shinichi; Kurata, Masaki*; Yahagi, Noboru*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 4 Pages, 2008/05

Products on solid cathodes recovered from metal pyrochemical processing were processed to obtain uranium ingot. Studies on process conditions for uranium forming, assay recovered uranium products and by-products and evaluation of mass balance were carried out. In this tests, it is confirmed that uranium ingots can be obtained with heating the products up to more than melting temperature of metal uranium under normal pressure because adhered salt cover the uranium not to oxidize it during uranium cohering. Volatilization of americium is very small under the condition of high temperature.

Journal Articles

Uranium, plutonium and neptunium co-recovery with irradiated fast reactor MOX fuel by single cycle extraction process

Nakahara, Masaumi; Sano, Yuichi; Nomura, Kazunori; Washiya, Tadahiro; Komaki, Jun

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 5 Pages, 2008/05

Among minor actinides, Np has a possibility to be co-recovered with U and Pu by tri-n-butylphosphate (TBP) according to its extractable valences; Np(IV) and Np(VI). Therefore, the Np valence needs to be adjusted to extractable Np(VI). In this process, partitioning section purification section are deleted, and the flow sheet is designed by single cycle. This works using the dissolver solution of irradiated MOX fuel from fast reactor "JOYO" has been carried out with centrifugal contactors, whose residence time is considerably smaller than that of mixer-settler. The feed solution is adjusted to having high HNO$$_{3}$$ concentration. This condition adjusts the Np valence for its extraction. As expected, about 99% of Np was recovered with U and Pu. Through this series of studies, the U, Pu and Np co-recovery process using high HNO$$_{3}$$ concentration feed solution was successfully demonstrated.

Journal Articles

Dissolution of powdered spent fuel and U crystallization from actual dissolver solution for "NEXT" process development

Nomura, Kazunori; Hinai, Hiroshi; Nakahara, Masaumi; Kaji, Naoya; Kamiya, Masayoshi; Oyama, Koichi; Sano, Yuichi; Washiya, Tadahiro; Komaki, Jun

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 5 Pages, 2008/05

Journal Articles

MA/Ln separation with new ligand, hydrophobic derivatives of TPEN

Matsumura, Tatsuro; Takeshita, Kenji*; Mori, Atsunori*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 4 Pages, 2008/05

JP, 2007-210038   Licensable Patent Information Database   Patent publication (In Japanese)

We are developing a new MA/Ln separation process with derivatives of TPEN (N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine) for P&T technology. TPEN is a hexadentate ligand, which has good selectivity of Am(III) from Ln(III). However, there is a serious problem for the practical application. This is to the dissolution of a slight amount of TPEN (about 10$$^{-4}$$ mol/l) to water. High enrichment of Am(III) will be restricted by the dissolution of TPEN to water. In this study, the hydrophobicity of TPEN is improved by introducing alkyl groups and the selectivity of Am(III) and Eu(III) is examined. We succeeded to synthesize a new hydrophobic derivative of TPEN, TBPEN (N,N,N',N'-tetrakis((5-butoxypyridin-2-yl)-methyl)ethylenediamine. It showed good selectivity and the maximum separation factor, SF$$_{rm Am/Eu}$$, was 91 at pH 3.0. A hydrophobic derivative of TPEN that has potential of application to the MA/Ln separation process was synthesized successfully.

Journal Articles

Extraction separation of Am(III) and Eu(III) with thermosensitive gel introducing TPEN derivatives

Takeshita, Kenji*; Nakano, Yoshio*; Matsumura, Tatsuro; Mori, Atsunori*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 8 Pages, 2008/05

A thermal-swing chromatographic process using a thermosensitive gel copolymerized with NIPA (N-isopropylacrylamide) and TPPEN (N,N,N',N'-tetrakis(4-propenyloxy-2-pyridylmethyl)ethylenediamine) was studied for the separation of Am(III) from Eu(III). Firstly, the radiolysis of the TPPEN-NIPA gel was tested by the $$gamma$$-ray irradiation and the $$alpha$$ nuclide adsorption. The extraction separation of Am(III) was not influenced in the radioactive environment of the proposed process. Next, the TPPEN-NIPA gel was immobilized in porous silica particles and the applicability of the gel-immobilized silica to the proposed process was tested. Am(III) was extracted selectively in the gel-immobilized silica at 5$$^{circ}$$C and the separation factor of Am(III) over Eu(III) was evaluated to be 3.7. The distribution ratio of Am(III) was reduced to less than 1/20 by increasing temperature from 5$$^{circ}$$C to 40$$^{circ}$$C. These results indicate that the TPPEN-NIPA gel is applicable to the thermal-swing chromatographic process for the MA recovery.

Journal Articles

Uranium recovery in LWR reprocessing and plutonium/residual uranium conditioning in FBR reprocessing for the transition from LWR to FBR

Fukasawa, Tetsuo*; Yamashita, Junichi*; Hoshino, Kuniyoshi*; Sasahira, Akira*; Inoue, Tadashi*; Minato, Kazuo; Sato, Seichi*

Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 7 Pages, 2008/05

In order to flexibly manage the transition period from LWR to FBR, the authors investigated the transition scenario and proposed the Flexible Fuel Cycle Initiative (FFCI). In FFCI, LWR spent fuel reprocessing only carries out the removal of about 90% uranium that will be purified and utilized in LWR after re-enrichment. The residual material (40% U, 15% Pu and 45% other nuclides) is transferred to temporary storage and/or FBR spent fuel reprocessing to recover Pu/U followed by FBR fresh fuel fabrication depending on the FBR introduction status. The FFCI has some merits compared with ordinary system that consists of full reprocessing facilities for both LWR and FBR spent fuels, that is smaller LWR reprocessing facility, spent LWR fuel reduction, storage and supply of high proliferation resistant and high Pu density material that can flexibly respond to FBR introduction rate changes. The Pu balance was calculated under several cases, which revealed that the FFCI could supply enough Pu to FBR in any cases.

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