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Journal Articles

Structural, magnetic, transport, and thermoelectric properties of the pseudobrookite AlTi$$_{2}$$O$$_{5}$$-Ti$$_{3}$$O$$_{5}$$ system

Takahama, Ryusei*; Ishii, Toi*; Indo, Daigo*; Arizono, Mitsutoshi*; Terakura, Chieko*; Tokura, Yoshinori*; Takeshita, Nao*; Noda, Masaaki*; Kuwahara, Hideki*; Saiki, Takuo*; et al.

Physical Review Materials (Internet), 4(7), p.074401_1 - 074401_11, 2020/07

 Times Cited Count:6 Percentile:40.97(Materials Science, Multidisciplinary)

Journal Articles

Fine dispersion of Pt$$_{4-5}$$ subnanoclusters and Pt single atoms over porous carbon supports and their structural analyses with X-ray absorption spectroscopy

Itoi, Hiroyuki*; Nishihara, Hirotomo*; Kobayashi, Shunsuke*; Ittisanronnachai, S.*; Ishii, Takafumi*; Berenguer, R.*; Ito, Masashi*; Matsumura, Daiju; Kyotani, Takashi*

Journal of Physical Chemistry C, 121(14), p.7892 - 7902, 2017/04

 Times Cited Count:30 Percentile:72.07(Chemistry, Physical)

Journal Articles

Extended steady-state and high-beta regimes of net-current free heliotron plasmas in the Large Helical Device

Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Muto, Takashi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.

Nuclear Fusion, 47(10), p.S668 - S676, 2007/10

 Times Cited Count:34 Percentile:73.8(Physics, Fluids & Plasmas)

The performance of net-current free heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fuelling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an internal diffusion barrier (IDB) by a combination of efficient pumping of the local island divertor function and core fuelling by pellet injection has realized a super dense core as high as 5$$times$$10$$^{20}$$ m$$^{-3}$$, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5% and a discharge duration of 54 min with a total input energy of 1.6 GJ (490 kW on average) are also highlighted. The progress of LHD experiments in these two years is overviewed by highlighting IDB, high-beta and long pulse.

Journal Articles

Extended steady-state and high-beta regimes of net-current free heliotron plasmas in the large helical device

Motojima, Osamu*; Yamada, Hiroshi*; Komori, Akio*; Oyabu, Nobuyoshi*; Kaneko, Osamu*; Kawahata, Kazuo*; Mito, Toshiyuki*; Muto, Takashi*; Ida, Katsumi*; Imagawa, Shinsaku*; et al.

Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 12 Pages, 2007/03

The performance of net-current free Heliotron plasmas has been developed by findings of innovative operational scenarios in conjunction with an upgrade of the heating power and the pumping/fueling capability in the Large Helical Device (LHD). Consequently, the operational regime has been extended, in particular, with regard to high density, long pulse length and high beta. Diversified studies in LHD have elucidated the advantages of net-current free heliotron plasmas. In particular, an Internal Diffusion Barrier (IDB) by combination of efficient pumping of the local island divertor function and core fueling by pellet injection has realized a super dense core as high as 5$$times$$10$$^{20}$$m$$^{-3}$$, which stimulates an attractive super dense core reactor. Achievements of a volume averaged beta of 4.5 % and a discharge duration of 54-min. with a total input energy of 1.6 GJ (490 kW in average) are also highlighted. The progress of LHD experiments in these two years is overviewed with highlighting IDB, high $$beta$$ and long pulse.

Oral presentation

Study of radiolysis of HONTA extractant for MA/Ln separation

Toigawa, Tomohiro; Suzuki, Hideya; Ban, Yasutoshi; Ishii, Sho; Matsumura, Tatsuro

no journal, , 

Degradation of extractants and generation of radiolytic products are considered as problem for feasibility of the minor actinides separation process. In this study, degradation amount of hexaoctyl-nitrilotriacetamide (HONTA), which is a candidate extaractant for MA/Ln separation, and its products yields were obtained by using $$gamma$$-rays emitted from Co-60. Our results showed the cleavage sites in HONTA radiolysis and suggest that the mechanism for HONTA radiolysis is differ depending on the absorbed dose.

Oral presentation

Radiolysis of HONTA extractant for MA/RE separation

Toigawa, Tomohiro; Suzuki, Hideya; Ban, Yasutoshi; Ishii, Sho*; Matsumura, Tatsuro

no journal, , 

R&D on partitioning process of the minor actinides (MA) from high level liquid waste (HLLW) were carried out for reduction of the strain on the radioactive wastes disposal. In this study, degradation amount of hexaoctyl-nitrilotriacetamide (HONTA), which is a candidate extaractant for MA/RE separation, and its products yields were obtained by using $$gamma$$-rays emitted from Co-60. Our results showed the cleavage sites in HONTA radiolysis and suggest that the mechanism for HONTA radiolysis is differ depending on the absorbed dose.

Oral presentation

$$gamma$$ radiolysis of an extractant for minor actinides, Hexaoctyl-nitrilotriacetamide (HONTA), in dodecane diluent

Toigawa, Tomohiro; Suzuki, Hideya; Ban, Yasutoshi; Ishii, Sho*; Matsumura, Tatsuro

no journal, , 

Radiolytic stability of an extractant, N,N,N',N',N'',N''-hexaoctyl-nitrilotriacetamide (HONTA), for separation between minor actinides and rare-earth elements were investigated by using $$gamma$$-ray emitting from cobalt-60. Degradation amount of HONTA and its products yields were obtained by gas chromatographic analysis. Our results showed the cleavage sites in HONTA radiolysis and suggested that the radiolysis of HONTA was ruled by different mechanism depending on the absorbed dose.

Oral presentation

Current status of R&D on minor actinide separation process with CHON Extractants in JAEA

Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; et al.

no journal, , 

To continue the utilization of the nuclear fission energy, the management of the high-level radioactive waste is one of the most important issues to be solved. Partitioning and Transmutation technology is expected to be effective to mitigate the burden of the HLW disposal by reducing the radiological toxicity and heat generation. JAEA has been conducting R&D on the MA separation process to remove of MA from HLW and supply the recovered MA to the transmutation system such as ADS. The MA separation process contains three steps. For An(III)+RE recovery process, we developed TDdDGA which has very high performance to recover of MA from high level waste. HONTA and ADAAM were developed for An(III)/RE separation process and Am/Cm separation process respectively. All extractants satisfy CHON principle to minimization of the secondary waste from the process. The separation performances of the flowsheets were evaluated by continuous extraction tests using simulated and genuine high level liquid waste.

Oral presentation

Current status of R&D on reprocessing and minor actinide separation process with CHON ligands in JAEA

Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; et al.

no journal, , 

PUREX process was established for industrial scale reprocessing plant. TRUEX and the 4 group separation were developed for partitioning of minor actinides from HLW, and demonstrated using genuine HLW. Although the extractants for the processes have excellent performance, the molecules contain phosphorus which could be cause for the secondary waste from the solvent extraction processes. To minimize the radioactive waste, we have conducted research and development of the new reprocessing and MA separation processes using innovative extractants in accord with CHON principle. The extractants for reprocessing process are monoamides as alternative extractants for TBP. For An(III)+RE recovery process, we developed TDdDGA. HONTA and ADAAM were developed for An(III)/RE separation process and Am/Cm separation process respectively. The separation performances of the flowsheets were evaluated by continuous extraction tests using simulated and genuine spent fuel and high level liquid waste.

Oral presentation

Influence of $$gamma$$-radiolysis of MA separation agent of HONTA on extraction performance

Toigawa, Tomohiro; Suzuki, Hideya; Ban, Yasutoshi; Ishii, Sho*; Matsumura, Tatsuro

no journal, , 

To evaluate the radiolytic stability of a novel tetradentate extractant of N, N, N', N', N", N"-hexaoctyl-nitrilotriacetamide (HONTA), batch extractions of lanthanide (Ln) elements were performed by using $$gamma$$-irradiated HONTA extraction solvents. The distribution ratios decreased exponentially with increasing the absorbed dose, and no difference between Ln could be observed. These indicate that the degradation products of HONTA did not act as Ln extractants, and the decay of Ln extraction were caused by degradation of HONTA.

Oral presentation

Influence of $$gamma$$-radiolysis of a minor actinide extractnt on lanthanides extraction

Toigawa, Tomohiro; Suzuki, Hideya; Ishii, Sho*; Tsutsui, Nao; Ban, Yasutoshi; Matsumura, Tatsuro

no journal, , 

To evaluate the radiolytic stability of an extractant agents for minor actinides such as N, N, N', N', N", N"-hexaoctyl-nitrilotriacetamide (HONTA), batch extractions of lanthanide (Ln) elements were performed by using $$gamma$$-irradiated extraction solvents. The distribution ratios decreased exponentially with increasing the absorbed dose, and no initial decrease could be observed.

Oral presentation

Solvent extraction process for reprocessing and minor actinides separation using CHON ligands

Matsumura, Tatsuro; Ban, Yasutoshi; Suzuki, Hideya; Tsubata, Yasuhiro; Hotoku, Shinobu; Tsutsui, Nao; Suzuki, Asuka; Toigawa, Tomohiro; Kurosawa, Tatsuya*; Shibata, Mitsunobu*; et al.

no journal, , 

PUREX process was established for industrial scale reprocessing plant. TRUEX and the 4 group separation were developed for partitioning of minor actinides from high level liquid waste from reprocessing process, and demonstrated by the continuous extraction test using genuine high level liquid waste. Although the extractants for reprocessing and MA separation processes, such as tri-n-butyl phosphate (TBP), n-octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide (CMPO) and diisodecylphosphoric acid (DIDPA), have excellent performance for recovery of U, Pu or MA, the molecules contain phosphorus which could be cause for the secondary waste from the solvent extraction processes. To minimize the radioactive waste from nuclear fuel cycle, we have conducted research and development of the new reprocessing and MA separation processes using innovative extractants in accord with CHON principle.

Oral presentation

Research and development of the "SELECT process" for actinide separation, 1; Concept

Matsumura, Tatsuro; Ban, Yasutoshi; Hotoku, Shinobu; Suzuki, Hideya; Tsubata, Yasuhiro; Tsutsui, Nao; Morita, Keisuke; Toigawa, Tomohiro; Shibata, Mitsunobu*; Kurosawa, Tatsuya*; et al.

no journal, , 

no abstracts in English

Oral presentation

Research and development of the "SELECT process" for Actinide separation

Matsumura, Tatsuro; Ban, Yasutoshi; Hotoku, Shinobu; Suzuki, Hideya; Tsubata, Yasuhiro; Tsutsui, Nao; Morita, Keisuke; Toigawa, Tomohiro; Shibata, Mitsunobu*; Kurosawa, Tatsuya*; et al.

no journal, , 

no abstracts in English

Oral presentation

Research and development of the "SELECT process" for actinide separation

Matsumura, Tatsuro; Ban, Yasutoshi; Hotoku, Shinobu; Suzuki, Hideya; Tsubata, Yasuhiro; Tsutsui, Nao; Morita, Keisuke; Toigawa, Tomohiro; Shibata, Mitsunobu*; Kurosawa, Tatsuya*; et al.

no journal, , 

no abstracts in English

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