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Yamamoto, Tomohiko; Okamura, Shigeki; Hirayama, Tomoyuki*; Morobishi, Ryota*; Endo, Naoki*; Adachi, Yoshihiko*
Yukuatsu Gijutsu, 63(12), p.22 - 26, 2024/11
JAEA is currently conducting research and development of a three-dimensional seismic isolation system as a measure to improve earthquake resistance in the research and development for the practical application of sodium-cooled fast reactors in the future. This paper presents an overview of the high-velocity oil damper, one of the components of the three-dimensional seismic isolation system that is currently being researched and developed.
Nasu, Mitsunori*; Yanai, Hiroshi*; Hirayama, Naoki*; Adachi, Hironori*; Kakizawa, Yu*; Shirase, Yuto*; Nishiyama, Hiromichi*; Kawamoto, Teppei*; Inukai, Junji*; Shinohara, Takenao; et al.
Journal of Power Sources, 530, p.231251_1 - 231251_11, 2022/05
Times Cited Count：44 Percentile：89.29(Chemistry, Physical)Okamura, Hiroyuki; Hirayama, Naoki*
Analytical Sciences, 37(1), p.119 - 130, 2021/01
Times Cited Count：49 Percentile：65.89(Chemistry, Analytical)This review summarizes recent progress in solvent extraction of rare earth elements (REEs) using an ionic liquid (IL) as the extraction solvent. These IL extraction systems are advantageous owing to the affinity of ILs for both charged and neutral hydrophobic species, in contrast to conventional organic solvent extraction systems. Herein, REE extraction studies using ILs are detailed and classified based on the type of extraction system. In IL extraction systems, the extracted complexes are often different from those in organic solvent systems, and the REE extraction and separation efficiencies are often significantly enhanced. Synergistic IL extraction is an effective approach to improving the extractability and separability of REEs. The development of novel task-specific ionic liquids (TSILs) suitable for IL extraction systems is also effective for REE separation.
Okamura, Hiroyuki; Mizuno, Masayoshi*; Hirayama, Naoki*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*
Industrial & Engineering Chemistry Research, 59(1), p.329 - 340, 2020/01
Times Cited Count：15 Percentile：41.20(Engineering, Chemical)The synergistic ionic-liquid extraction and extraction equilibrium of lanthanoid(III) (Ln(III)) ions have been investigated using 2-thenoyltrifluoroacetone (Htta) and trioctylphosphine oxide (TOPO) in the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([C
mim][Tf
N]). The selective synergistic effect for heavier Ln(III) ions was found using a combination of Htta and TOPO in [Cmim][TfN], leading to enhanced separability among Ln(III) ions. The extracted Ln(III) species and the extraction constants in the Htta-TOPO system were determined by three-dimensional extraction equilibrium analysis. The selective synergism for heavier Ln(III) ions in the Htta-TOPO system was ascribed to the formation of hydrophobic, charged adducts, such as Ln(tta)(TOPO)
and Ln(tta)(TOPO)
, in [Cmim][TfN].
Wang, H.*; Otsu, Hideaki*; Chiga, Nobuyuki*; Kawase, Shoichiro*; Takeuchi, Satoshi*; Sumikama, Toshiyuki*; Koyama, Shumpei*; Sakurai, Hiroyoshi*; Watanabe, Yukinobu*; Nakayama, Shinsuke; et al.
Communications Physics (Internet), 2(1), p.78_1 - 78_6, 2019/07
Times Cited Count：10 Percentile：53.52(Physics, Multidisciplinary)Searching for effective pathways for the production of proton- and neutron-rich isotopes through an optimal combination of reaction mechanism and energy is one of the main driving forces behind experimental and theoretical nuclear reaction studies as well as for practical applications in nuclear transmutation of radioactive waste. We report on a study on incomplete fusion induced by deuteron, which contains one proton and one neutron with a weak binding energy and is easily broken up. This reaction study was achieved by measuring directly the cross sections for both proton and deuteron for 
Pd at 50 MeV/u via inverse kinematics technique. The results provide direct experimental evidence for the onset of a cross-section enhancement at high energy, indicating the potential of incomplete fusion induced by loosely-bound nuclei for creating proton-rich isotopes and nuclear transmutation of radioactive waste.
Kunieda, Satoshi; Iwamoto, Osamu; Iwamoto, Nobuyuki; Minato, Futoshi; Okamoto, Tsutomu; Sato, Tatsuhiko; Nakashima, Hiroshi; Iwamoto, Yosuke; Iwamoto, Hiroki; Kitatani, Fumito; et al.
JAEA-Conf 2016-004, p.41 - 46, 2016/09
Neutron- and proton-induced cross-section data are required in a wide energy range beyond 20 MeV, for the design of accelerator applications. New evaluations are performed with recent knowledge in the optical and pre-equilibrium model calculations. We also evaluated cross-sections for p+
Li and p+
Be which have been highly requested from a medical field. The present high-energy nuclear data library, JENDL-4.0/HE, includes evaluated cross-sections for incident neutrons and protons up to 200 MeV (for about 130 nuclei). We overview substantial features of the library, i.e., (1) systematic evaluation with CCONE code, (2) challenges for evaluations of light nuclei and (3) inheritance of JENDL-4.0 and JENDL/HE-2007. In this talk, we also focus on the results of benchmark calculation for neutronics to show performance of the present library.
Okamura, Hiroyuki; Ikeda, Atsushi*; Saito, Takumi*; Aoyagi, Noboru; Naganawa, Hirochika; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Shimojo, Kojiro
Analytical Chemistry, 84(21), p.9332 - 9339, 2012/11
Times Cited Count：24 Percentile：60.80(Chemistry, Analytical)Okamura, Hiroyuki; Sakae, Hiroki*; Kidani, Keiji*; Hirayama, Naoki*; Aoyagi, Noboru; Saito, Takumi*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*
Polyhedron, 31(1), p.748 - 753, 2012/01
Times Cited Count：30 Percentile：87.38(Chemistry, Inorganic & Nuclear)Okamura, Hiroyuki; Hirayama, Naoki*; Morita, Kotaro*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*
Analytical Sciences, 26(5), p.607 - 611, 2010/05
Times Cited Count：56 Percentile：84.14(Chemistry, Analytical)
-diketone fragments on an ionic liquid extraction systemShimojo, Kojiro; Okamura, Hiroyuki; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Naganawa, Hirochika
Dalton Transactions, 2009(25), p.4850 - 4852, 2009/07
A novel extractant -diketone-substituted diaza-18-crown-6 demonstrated very efficient extraction of Sr due to an intramolecular synergistic effect on the ionic liquid extraction system and recovery of Sr from the ionic liquid was successfully achieved under acidic conditions.
; Sakamoto, Yukio; Tanaka, Shunichi; ; Fukahori, Tokio; ; Sasamoto, Nobuo; Tanaka, Susumu; Nakamura, Takashi*; Shin, Kazuo*; et al.
JAERI-Data/Code 94-012, 90 Pages, 1994/09
JAERI-Data-Code-94-012.pdf:2.26MB
no abstracts in English
Okamura, Hiroyuki; Shimojo, Kojiro; Ikeda, Atsushi; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Naganawa, Hirochika
no journal, ,
no abstracts in English
-diketone fragmentsOkamura, Hiroyuki; Shimojo, Kojiro; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Naganawa, Hirochika
no journal, ,
no abstracts in English
-diketone fragmentsShimojo, Kojiro; Okamura, Hiroyuki; Ikeda, Atsushi; Saito, Takumi*; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Naganawa, Hirochika
no journal, ,
no abstracts in English
Okamura, Hiroyuki; Shimojo, Kojiro; Hirayama, Naoki*; Imura, Hisanori*; Naganawa, Hirochika
no journal, ,
no abstracts in English
Okamura, Hiroyuki; Shimojo, Kojiro; Hirayama, Naoki*; Umetani, Shigeo*; Imura, Hisanori*; Naganawa, Hirochika
no journal, ,
no abstracts in English
Eguchi, Ayano; Morita, Kotaro*; Okamura, Hiroyuki; Hirayama, Naoki*
no journal, ,
In chelate extraction of metal ions into conventional organic solvents, the metals are generally extracted as uncharged complexes. Moreover, coordinatively saturated (unhydrated) complexes are preferable as extracted species. In ionic liquid (IL) chelate extraction, on the contrary, also charged species or coordinatively unsaturated (hydrated) species can be extracted. In this study, we investigated the IL chelate extraction behavior of trivalent metal ions, Fe(III), Al(III), Ga(III) and In(III), into 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imides ([C
mim][TfN], n = 2, 4, 8) using 8-quinolinol (HQ
) and 2-mercaptopyridine 
-oxide (HSPyO) as bidentate ligands. In the case of HQ, only uncharged M
Q
was extracted into chloroform, whereas coordinatively unsaturated cationic complex [MQ
] was also extracted into ILs by ion exchange. In the case of HSPyO, it was implied that uncharged M(SPyO) was extracted into both chloroform and ILs. Therefore, the extracted species depends on the ligands in ILs.
-oxideEguchi, Ayano; Morita, Kotaro*; Okamura, Hiroyuki; Hirayama, Naoki*
no journal, ,
2-Mercaptopyridine -oxide (HSPyO) is a bidentate ligand with a hard O-donor and a soft S-donor. This ligand is expected to be effective in an ionic liquid (IL) chelate extraction because of its high solubility in ILs. In this study, we investigated the IL chelate extraction behavior of Al(III), Ga(III), and In(III) into ILs, 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imides ([Cmim][TfN], n = 2, 4, 8), using HSPyO as an extractant. The extraction selectivity order was In(III) 
Ga(III), whereas Al(III) was not extracted. Therefore, HSPyO was favorable for the extraction of soft In(III). The extractability order for solvents was ILs chloroform in the Ga(III) extraction, indicating that ILs exhibit high extraction performance. In addition, it was implied that the extracted species were the neutral complexes, M(SPyO), for all metals.
Okamura, Hiroyuki; Shimojo, Kojiro; Hirayama, Naoki*; Imura, Hisanori*; Naganawa, Hirochika
no journal, ,
no abstracts in English
Okamura, Hiroyuki; Hirayama, Naoki*; Shimojo, Kojiro; Naganawa, Hirochika; Imura, Hisanori*
no journal, ,
no abstracts in English
