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Koma, Yoshikazu; Watanabe, So; Sano, Yuichi; Asakura, Toshihide; Morita, Yasuji
Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 8 Pages, 2008/05
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.
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
(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).
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
and NpO
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. The thermal conductivities of AmO and NpO were evaluated from the measured thermal diffusivities, heat capacities and bulk densities. The thermal conductivity of AmO was smaller than those of the literature values of UO and PuO. On the other hand, the thermal conductivity of NpO from 873 to 1473 K lay between those of UO and PuO. The thermal conductivities of AmO and NpO decreased with increasing temperature in the temperature range investigated.
-UCl meltFukushima, 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.
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 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 concentration feed solution was successfully demonstrated.
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
Matsumura, Tatsuro; Takeshita, Kenji*; Mori, Atsunori*
Proceedings of 3rd International ATALANTE Conference (ATALANTE 2008) (CD-ROM), 4 Pages, 2008/05
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
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
, 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.
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 
-ray irradiation and the 
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
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 5C to 40C. These results indicate that the TPPEN-NIPA gel is applicable to the thermal-swing chromatographic process for the MA recovery.
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.
Nagaoka, Shinichi; Morimoto, Kazuyuki; Kitao, Takahiko; Obu, Tomoyuki; Kanamori, Sadamu; Omori, Eiichi
no journal, ,
40
50% of neptunium (Np) was distributed to product stream in Tokai Reprocessing Plant (TRP) at present. We tried to increase acidity of second extraction cycle within available operating parameter, and by measuring neptunium concentration at outlet stage in second extraction cycle, we verified that 6070% of neptunium was distributed to product stream. Also we warmed up solutions in contactors of second extraction cycle within available operating parameter to make sure oxidation of neptunium on actual process, and we verified that 70% of neptunium was distributed to product stream. We confirmed that increasing acidity and warming up solutions was effective for Pu-U-Np co-extraction on the engineering scale reprocessing facility.
Kurata, Masaki*; Yahagi, Noboru*; Kitawaki, Shinichi; Nakayoshi, Akira; Fukushima, Mineo
no journal, ,
CRIEPI and JAEA are continuing a collaboration study for metal pyro-processing, in which sequential process tests have been performed under practical conditions using 1kg of molten salt baths. Recent results on two kinds of sequential process test are reported. The former is the electro-chemical reduction test of MOX pellet in order to form U-Pu alloy ingots. The latter is the electrolysis test using a combination of U-Pu alloy anode and solid or liquid cadmium cathode to recover U-product or U-Pu-Am alloy product, respectively. Variation in electrode potentials, current efficiency, molten salt composition, Pu- or Am-impurity in the U-product, U/Pu or Am/Pu separation factor in the U-Pu alloy product, and etc. were measured. These tests reproduced practical operating conditions at a scale of 1/1000 that of the actual process.
Nomura, Shigeo; Yamamoto, Ryuichi
no journal, ,
The current LWR cycle composed of PUREX reprocessing and MOX fuel fabrication technologies becomes a matured industrial level. However, advanced fuel cycle will be realized with the mid and long term R&D, focusing the transition period which handles at least three types of spent fuel; LWR-UOX, LWR-MOX, and FBR-MOX to produce mainly advanced reactor fuels for FBR. R&D scheme becomes more complicated, because of such kinds of spent fuels and products, succession of the current industrial technologies, and future social and technological needs. Under these conditions, two types of R&D; evolutionary and revolutionary ones are proposed. The modification and partial replacement of the current technologies can be realized through the evolutionary type R&D. The introduction of new concept and the drastic change of main process are categorized for the revolutionary R&D. Progress of such R&D is implemented by the four stages as a classic linear model. The linear model should be modified and skipped sometime by finding out how to apply the simulation model and the conventional outcomes developed in the past. The engineering demonstration should be implemented especially for the verification of design, performance, and operation including off-normal conditions. Most of JAEA facilities cover the evolutionary type R&D from basic to engineering stage. To implement the revolutionary type R&D, however, these should prepare more flexible testing parameters, new machines and process equipments, depending upon the each progress of candidate technologies.