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Okuma, Ryutaro*; Kofu, Maiko; Asai, Shinichiro*; Avdeev, M.*; Koda, Akihiro*; Okabe, Hirotaka*; Hiraishi, Masatoshi*; Takeshita, Soshi*; Kojima, Kenji*; Kadono, Ryosuke*; et al.
Nature Communications (Internet), 12, p.4382_1 - 4382_7, 2021/07
Times Cited Count：6 Percentile：61.42(Multidisciplinary Sciences)Kofu, Maiko; Watanuki, Ryuta*; Sakakibara, Toshiro*; Kawamura, Seiko; Nakajima, Kenji; Matsuura, Masato*; Ueki, Takeshi*; Akutsu, Kazuhiro*; Yamamuro, Osamu*
Scientific Reports (Internet), 11(1), p.12098_1 - 12098_8, 2021/06
Times Cited Count：5 Percentile：56.02(Multidisciplinary Sciences)Kawakita, Yukinobu; Kikuchi, Tatsuya*; Inamura, Yasuhiro; Tahara, Shuta*; Maruyama, Kenji*; Hanashima, Takayasu*; Nakamura, Mitsutaka; Kiyanagi, Ryoji; Yamauchi, Yasuhiro*; Chiba, Kaori*; et al.
Physica B; Condensed Matter, 551, p.291 - 296, 2018/12
Times Cited Count：11 Percentile：48.06(Physics, Condensed Matter)There are elemental liquid metals with complex structures far from the hard sphere (HS) packing model. Liquid Bi has an asymmetric first peak in the structure factors S(Q). The pair distribution function g(r) exhibits strange distance ratio of 1:2 between the first and the second peaks. Since a HS model with two kinds of radius produces asymmetry of the main peak in S(Q), existence of short-lived covalent bonds was discussed. Contrarily, modulation of the atomic distribution by the Friedel oscillations of shielding electrons around metallic ions was discussed. To examine its bonding nature from viewpoints of dynamic correlation functions, we have measured neutron quasielastic scattering of liquid Bi by using cold disk chopper spectrometer installed at MLF of J-PARC. The van Hove function revealed that the shoulder structure located at a longer side of the first peak in g(r) exhibits a longer relaxation time than the main structures such as the first and second peaks.
Kajimoto, Ryoichi; Nakamura, Mitsutaka; Inamura, Yasuhiro; Kamazawa, Kazuya*; Ikeuchi, Kazuhiko*; Iida, Kazuki*; Ishikado, Motoyuki*; Murai, Naoki; Kira, Hiroshi*; Nakatani, Takeshi; et al.
Journal of Physics; Conference Series, 1021(1), p.012030_1 - 012030_6, 2018/06
Times Cited Count：3 Percentile：88.67(Nuclear Science & Technology)
C level structure by 
-ray spectroscopyHosomi, Kenji; Ma, Y.*; Ajimura, Shuhei*; Aoki, Kanae*; Dairaku, Seishi*; Fu, Y.*; Fujioka, Hiroyuki*; Futatsukawa, Kenta*; Imoto, Wataru*; Kakiguchi, Yutaka*; et al.
Progress of Theoretical and Experimental Physics (Internet), 2015(8), p.081D01_1 - 081D01_8, 2015/08
Times Cited Count：14 Percentile：66.59(Physics, Multidisciplinary)Level structure of the C hypernucleus was precisely determined by means of -ray spectroscopy. We identified four -ray transitions via the 
C
reaction using a germanium detector array, Hyperball2. The spacing of the ground-state doublet 
was measured to be 
(stat)
(syst)keV from the direct 
transition. Excitation energies of the 
and 
states were measured to be 
, keV and 
, keV, respectively. The obtained level energies provide definitive references for the reaction spectroscopy of 
hypernuclei.
Kanai, Akihiko*; Kasada, Ryuta*; Nakajima, Motoki; Hirose, Takanori; Tanigawa, Hisashi; Enoeda, Mikio; Konishi, Satoshi*
Journal of Nuclear Materials, 455(1-3), p.431 - 435, 2014/12
Times Cited Count：0 Percentile：0.01(Materials Science, Multidisciplinary)Iguchi, Masahide; Morimoto, Masaaki; Chida, Yutaka*; Hemmi, Tsutomu; Nakajima, Hideo; Nakahira, Masataka; Koizumi, Norikiyo; Yamamoto, Akio*; Miyake, Takashi*; Sawa, Naoki*
IEEE Transactions on Applied Superconductivity, 24(3), p.3801004_1 - 3801004_4, 2014/06
Times Cited Count：6 Percentile：35.68(Engineering, Electrical & Electronic)no abstracts in English
Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.
Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10
Times Cited Count：10 Percentile：61.16(Nuclear Science & Technology)ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.
Nakajima, Hideo; Hemmi, Tsutomu; Iguchi, Masahide; Nabara, Yoshihiro; Matsui, Kunihiro; Chida, Yutaka; Kajitani, Hideki; Takano, Katsutoshi; Isono, Takaaki; Koizumi, Norikiyo; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03
The ITER organization and 6 Domestic Agencies (DA) have been implementing the construction of ITER superconducting magnet systems. Four DAs have already started full scale construction of Toroidal Field (TF) coil conductors. The qualification of the radial plate manufacture has been completed, and JA and EU are ready for full scale construction. JA has qualified full manufacturing processes of the winding pack with a 1/3 prototype and made 2 full scale mock-ups of the basic segments of TF coil structure to optimize and industrialize the manufacturing process. Preparation and qualification of the full scale construction of the TF coil winding is underway by EU. Procurement of the manufacturing equipment is near completion and qualification of manufacturing processes has already started. The constructions of other components of the ITER magnet systems are also going well towards the main goal of the first plasma in 2020.
Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Takano, Katsutoshi; Tsutsumi, Fumiaki; Chida, Yutaka; Nakajima, Hideo
AIP Conference Proceedings 1435, p.70 - 77, 2012/06
Times Cited Count：2 Percentile：63.67(Physics, Applied)A prediction method for tensile strengths at liquid helium temperature (4K) has been developed in order to rationalize qualification tests of cryogenic structural materials used in large superconducting magnet for a fusion device. This method is to use quadratic curves which are expressed as a function of carbon and nitrogen contents and strengths at room temperature. This study shows results of tensile tests at 4K and confirmation of accuracy of prediction method for tensile strengths at 4K for large forgings and thick hot rolled plates of austenitic stainless steels, which can be used in the actual coil case and radial plates of the ITER toroidal field coils. These products are 316LN having high nitrogen from 0.09 to 0.24% and maximum thickness is 600mm. As the results, it was confirmed that the tensile strengths of these products at 4K can be predicted by using appropriate quadratic curves. And distribution of strengths for each product was estimated.
Iguchi, Masahide; Chida, Yutaka; Takano, Katsutoshi; Kawano, Katsumi; Saito, Toru; Nakajima, Hideo; Koizumi, Norikiyo; Minemura, Toshiyuki*; Ogata, Hiroshige*; Ogawa, Tsuyoshi*; et al.
IEEE Transactions on Applied Superconductivity, 22(3), p.4203305_1 - 4203305_5, 2012/06
Times Cited Count：9 Percentile：47.58(Engineering, Electrical & Electronic)Japan Atomic Energy Agency (JAEA) has responsibility to procure 19 structures for ITER toroidal field (TF) coils as in-kind components. JAEA plans to use materials specified in the material section of "Codes for Fusion Facilities; Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in 2008. Large forged products were produced and their mechanical properties at 4K were evaluated. In addition, the following activities have been performed; (1) to optimize the design of each weld type identified in the manufacturing sequence, (2) to qualify typical welding procedure including repair, (3) to establish welding techniques other than narrow gap TIG welding with FMYJJ1, (4) to demonstrate the manufacturing procedures through manufacture of 1-m mockups and full-scale segments of TFC structure. This paper describes the results of material qualification and industrialization activities of manufacturing processes of ITER TFC structure.
Koizumi, Norikiyo; Matsui, Kunihiro; Hemmi, Tsutomu; Takano, Katsutoshi; Chida, Yutaka; Iguchi, Masahide; Nakajima, Hideo; Shimada, Mamoru*; Osemochi, Koichi*; Makino, Yoshinobu*; et al.
IEEE Transactions on Applied Superconductivity, 22(3), p.4200404_1 - 4200404_4, 2012/06
Times Cited Count：9 Percentile：47.58(Engineering, Electrical & Electronic)JAEA started sub- and full-scale trials to qualify and optimize manufacturing procedure of ITER TF coil from March, 2009. As major outcome of these trials, automatic winding system with accuracy in conductor length measurement of 0.01% has been established and the elongation of the conductor length due to heat treatment was measured to be 0.06%. To confirm validity of these outcomes, the authors carried out winding of a one-third scale dummy double pancake (DP), followed by its insulation and impregnation trial, and, in addition, heat treatment of one-third scale DP with real a TF conductor. The details about these trials are described in the other paper. The authors also performed trial manufacture of full scale RP and CPs for dummy double pancake, which will be made in near future. The full scale RP is manufactured by machining 10 segments in parallel to shorten machining duration and joining each segment by welding. In our trial manufacture of the full scale RP, hot-rolled SS316LN plates are machined to a final dimension, namely without additional material, and these segments are laser-welded. From these trials, manufacturing procedure of a thick hot-roll SS316LN plate is qualified and machining procedure is established, while more optimization may be necessary to achieve the required schedule and cost.
Iguchi, Masahide; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Miyabe, Keisuke*; Tokai, Daisuke*; Niimi, Kenichiro*
Teion Kogaku, 47(3), p.193 - 199, 2012/03
Japan Atomic Energy Agency (JAEA) has conducted qualification and rationalization activities in Japan in order to rationalize manufacturing procedure of ITER Toroidal Field (TF) coil structures. The activities included qualification of structural materials and qualification of welding procedure according to Japan Society of Mechanical Engineers (JSME) code constituted for fusion devices, demonstration of the manufacturing method and procedures through full-scale segments of TF coil structure. From results of these activities, JAEA confirmed applicability of JSME code to actual series TF coil structures as quality control method hence the quality of structural materials and weld joints of Gas Tungsten Arc Welding (GTAW) were satisfied ITER requirement. In addition, JAEA obtained knowledge of welding deformation of actual TF coil structures. This paper describes results of these qualification and development activities for TF coil structure.
Nagamoto, Yoshifumi*; Osemochi, Koichi*; Shimada, Mamoru*; Senda, Ikuo*; Koizumi, Norikiyo; Chida, Yutaka; Iguchi, Masahide; Nakajima, Hideo
Teion Kogaku, 47(3), p.200 - 205, 2012/03
Based on the results of the sub- and full-scale trials, the TF coil and TF coil structure manufacturing procedures were considered. Radial plate (RP) will be manufactured by assembling 10 sets of segments with Laser Beam Welding. Cover plates (CPs) will be manufactured by 3 different methods, depending on their geometry. For Winding pack (WP), winding system to enable to measurement of the conductor length with the accuracy of 0.01% for serial production was designed. Assembling procedure and groove types of narrow gap TIG welding for coil structures were determined. Hereafter, technical improvements will be considered in order to aim for further optimization of manufacturing.
Chida, Yutaka; Iguchi, Masahide; Takano, Katsutoshi; Nakajima, Hideo; Osemochi, Koichi*; Niimi, Kenichiro*; Tokai, Daisuke*; Gallix, R.*
Fusion Engineering and Design, 86(12), p.2900 - 2903, 2011/12
Times Cited Count：10 Percentile：60.88(Nuclear Science & Technology)TF coil structures, which support large electromagnetic force generated in TF coils under the cryogenic temperature (about 4K), are the mega welding structures composed of coil case and support structures made of high strength and high toughness stainless steel. JAEA started the study on welding trials for heavy thickness materials since 2008 and is planning of full scale mock-up model fabrication for main sub-components (1 set of inboard side and 1set of outboard side) in 2010 in order to investigate the technical issues for manufacturing of TF coil structures. This paper introduces the results on welding trials and status of full scale mock-up model fabrication to confirm the validity of welding technology and manufacturing design before fabricating actual products.
Chida, Yutaka; Iguchi, Masahide; Nakajima, Hideo; Osemochi, Koichi*; Niimi, Kenichiro*; Tokai, Daisuke*
Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 5 Pages, 2011/07
The Japan Atomic Energy Agency (JAEA), acting as the Japan Domestic Energy Agency (JADA) in the ITER project, is responsible for the procurement of structures for 19 TF coils (including one spare). TF coil structures, which support large electromagnetic force generated in TF coils under the cryogenic temperature (about 4K), are the mega welding structures composed of coil case and support structures made of high strength and high toughness stainless steel. JAEA started the study on welding trials for heavy thickness materials since 2008 and is demonstrating of full scale mock-up model fabrication for main sub-components in 2010 in order to investigate the technical issues for manufacturing of TF coil structures. This paper introduces the results on welding trials and status of full scale mock-up model fabrication to confirm the validity of welding technology and manufacturing design before fabricating actual products. Enough weld joint performance was obtained with the base metal of JJ1 (high strength and high toughness stainless steel developed in Japan) and SS316LN, and also their combination using JJ1 filler wire (developed in Japan) by narrow gap GTAW process. Welding deformation such as angular distortion between outer plate and side plate of U-shape segment could be controlled and minimized by using effective restraint jig and no defects was observed in the welds by radiographic testing (RT) in trial manufacturing of 1m length. Validity of welding technology and manufacturing design such as fabrication sequence, welding procedure specification (WPS), quality control plan is confirmed during full scale mock-up model fabrication.
Chida, Yutaka; Nakajima, Hideo
FAPIG, (182), p.15 - 20, 2011/02
no abstracts in English
Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; Toi, Kazuo*; Ogawa, Yuichi*; Takenaga, Hidenobu; Takizuka, Tomonori; Yagi, Masatoshi*; Yamada, Hiroshi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 84(1), p.70 - 72, 2008/01
no abstracts in English
Sasao, Mamiko*; Kusama, Yoshinori; Kawano, Yasunori; Kawahata, Kazuo*; Mase, Atsushi*; Sugie, Tatsuo; Fujita, Takaaki; Fukuda, Takeshi*; Fukuyama, Atsushi*; Sakamoto, Yoshiteru; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 83(9), p.779 - 782, 2007/09
This is a report of highlights from 2007 spring meetings of seven Topical Groups (TG) of International Tokamak Physics Activity (ITPA). In each meeting, high priority issues in physics of International Thermonuclear Experimental Reactor (ITER) and other burning plasma experiments have been discussed and investigated. Twenty-seven scientists from Japan have participated in those meetings. Dates and places of the meetings are shown below. (1) Diagnostics TG: 26-30 March, Princeton (USA), (2) Transport Physics TG: 7-10 May, Lausanne (Switzerland), (3) Confinement Database and Modeling TG: 7-10 May, Lausanne (Switzerland), (4) Edge Pedestal Physics TG: 7-10 May, Garching (Germany) (5) Steady State Operation TG: 9-11 May, Daejeon (South Korea), (6)MHD TG: 21-24 May, San Diego (USA), (7) Scrape-off-layer and Divertor Physics TG: 7-10 May, Garching (Germany).
Terada, Atsuhiko; Hino, Ryutaro; Hirayama, Toshio; Nakajima, Norihiro; Sugiyama, Hitoshi*
Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04
The Japan Atomic Energy Agency has been conducting study on thermochemical IS process for water splitting hydrogen production. Based on the test results and know-how obtained through the bench-scale test, a pilot test plant, which has a hydrogen production performance of 30 Nm
/h, is being designed conceptually as the next step of the IS process development. In design of the IS pilot plant, it is important to make chemical reactors compact with high performance from the viewpoint of plant cost reduction. A new hydraulic analytical code has been developed for optimizing mixing performance of multi-phase flow involving chemical reactions especially in the Bunsen reactor. Preliminary analytical results obtained with above mentioned code, especially flow patterns induced by swirling flow agreed well with that measured by water experiments, which showed vortex breakdown pattern in a simplified Bunsen reactor.
