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Toigawa, Tomohiro; Tsubata, Yasuhiro; Kai, Takeshi; Furuta, Takuya; Kumagai, Yuta; Matsumura, Tatsuro
Solvent Extraction and Ion Exchange, 39(1), p.74 - 89, 2021/00
Times Cited Count：2 Percentile：7.60(Chemistry, Multidisciplinary)Absorbed-dose estimation is essential for evaluation of the radiation feasibility of minor-actinide-separation processes. We propose a dose-evaluation method based on radiation permeability, with comparisons of heterogeneous structures seen in the solvent-extraction process, such as emulsions forming in the mixture of the organic and aqueous phases. A demonstration of radiation-energy-transfer simulation is performed with a focus on the minor-actinide-recovery process from high-level liquid waste with the aid of the Monte Carlo radiation-transport code PHITS. The simulation results indicate that the dose absorbed by the extraction solvent from alpha ray depends upon the emulsion structure, and that from beta and gamma ray depends upon the mixer-settler-apparatus size. Non-negligible contributions of well-permeable gamma rays were indicated in terms of the plant operation of the minor-actinide-separation process.
Toigawa, Tomohiro; Murayama, Rin*; Kumagai, Yuta; Yamashita, Shinichi*; Suzuki, Hideya; Ban, Yasutoshi; Matsumura, Tatsuro
UTNL-R-0501, p.24 - 25, 2020/12
This report summarizes the results obtained in FY2019 at Electron Linac Facility of University of Tokyo. The radiolysis process of a diglycolamide extractant, which is expected to be used in the separation process of minor actinides (MA), in dodecane and octanol solutions was investigated by pulse radiolysis. As a result, it was suggested that by adding alcohol, the decomposition process of the diglycolamide extractant was different from the decomposition processes in the single solvent of dodecane considered that the decomposition occurred via a radical cation species of the extractant.
Suzuki, Hideya; Tsubata, Yasuhiro; Kurosawa, Tatsuya*; Sagawa, Hiroshi*; Matsumura, Tatsuro
Journal of Nuclear Science and Technology, 54(11), p.1163 - 1167, 2017/11
Times Cited Count：31 Percentile：93.51(Nuclear Science & Technology)A highly practical diamide-type extractant, which is an alkyl diamide amine with 2-ethylhexyl alkyl chains (ADAAM(EH)), was investigated for mutual separation of Am(III) and Cm(III). ADAAM(EH) is a multidentate ligand with one soft N-donor atom and two hard O-donor atoms in its central frame. This tridentate arrangement of donor atoms provides selective binding to Am(III) compared to that with Cm(III) in highly acidic media, resulting in separation factors of up to 5.5. A continuous liquid-liquid extraction and stripping test was conducted using a multistage countercurrent mixer-settler extractor with ADAAM(EH) in n-dodecane. In this test, separation of Am(III) and Cm(III) was achieved with very high yield.
Matsumura, Tatsuro; Takeshita, Kenji*
ACS Symposium Series, 933, p.261 - 273, 2006/07
Three TPEN isomers with different positon of nitrogen donor in pyridyl groups, t2pen, t3pen and t4pen, were synthesized and the extraction separation of Am(III) and Eu(III) with these ligands and a fatty acid, decanoic acid, was investigated. All isomers were similar in the complexation in the aqueous phase, such as the protonation and the formation of metal complex, however, they showed different extraction behavior of Am and Eu. The synergistic extraction effect for Am was observed for t2pen and the high separation factor about 100 was measured, when 1:2. The value is comparable to that for the extraction system with a famous nitrogen-donor extractant, BTP. On the other hand, the extractability of other isomers was very low and no separation of Am and Eu was observed. Only t2pen, in which nitrogen donor in pyridyl groups is positioned in the vicinity of the skeletal structure (N-C-C-N structure) of ligand, is available for the extraction separation of Am.
Mirvaliev, R.*; Watanabe, Masayuki; Matsumura, Tatsuro; Tachimori, Shoichi*; Takeshita, Kenji*
Journal of Nuclear Science and Technology, 41(11), p.1122 - 1124, 2004/11
Times Cited Count：21 Percentile：77.13(Nuclear Science & Technology)Transmutation is a technology aimed to reduce HLW from reprocessing process. Minor actinides in the HLW will be converted to short-lived nuclides. However, lanthanides in HLW adversely affects on the efficiency of the transmutation. It is well known that separating An(III) and Ln(III) is very difficult because of their similarity of chemical properties. Therefore, the separation is one of the essential subjects to establish the transmutation technology. Considerable efforts have been devoted to the development of new extractants for the separation. N,N,N',N'-tetrakis(2-methylpyridyl)ethylenediamine (TPEN) demonstrates 100-fold preference for Am(III) over Ln(III) between stability constants with the ions in the aqueous phase. We have reported that Am(III) was selectively extracted from the aqueous phase containing Ln(III) by TPEN in nitrobenzene system and synergistic system with TPEN and D2EHPA in octanol. This work presents our recent results that Am(III) is separated from Eu(III) by a synergistic extraction system with TPEN and decanoic acid diluted with 1-octanol.
Wei, Y.*; Hoshi, Harutaka*; Kumagai, Mikio*; Asakura, Toshihide; Uchiyama, Gunzo*
Journal of Nuclear Science and Technology, 39(Suppl.3), p.761 - 764, 2002/11
To separate long-lived minor actinides and specific fission products such as Zr and Mo from nitrate acidic high-level liquid waste, we studied an advanced partitioning process by extraction chromatography using minimal organic solvent and compact equipment. In this work, we synthesized several new type of nitrogen donor ligands, 2,6-bi-(5,6-dialkyl-1,2,4-triazine-3-yl)-pyridine (R-BTP) with different alkyl groups and prepared novel silica-based extraction-resins by impregnating these ligands into the SiO
-P support with a diameter of 50 
m. The adsorption performance of 
Am and Ln (III) from nitrate solution was investigated. It was found that the adsorption behavior depends strongly on the alkyl group in R-BTP. 
Bu-BTP/SiO-P and Hex-BTP/SiO-P showed high absorbability and selectivity for Am (III) over Ln (III). The separation factor is about 10
for Am/Ce and near 10
for Am/Eu-Gd, respectively. Effective Am (III) separation form Ln (III) by extraction chromatography using R-BTP/SiO-P extraction-resins is expected.
Miyazaki, Yasunori; Toigawa, Tomohiro; Gejo, Tatsuo*; Kumaki, Fumitoshi*; Adachi, Junichi*; Nagasaka, Masanari*
no journal, ,
Nakamura, Hirofumi; Kihara, Yoshiyuki; Koyama, Shinichi; Tanaka, Kosuke; Katsuyama, Kozo; Soga, Tomonori; Maeda, Shigetaka; Takeuchi, Masayuki
no journal, ,
