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Journal Articles

Overview on recent progress toward small specimen test technique

Wakai, Eiichi; Kikuchi, Takayuki; Kim, B.*; Kimura, Akihiko*; Nogami, Shuhei*; Hasegawa, Akira*; Nishimura, Arata*; Soldaini, M.*; Yamamoto, Michiyoshi*; Knaster, J.*

Fusion Engineering and Design, 98-99, p.2089 - 2093, 2015/10

 Times Cited Count:10 Percentile:73.32(Nuclear Science & Technology)

Journal Articles

Evaluation of inter-laminar shear strength of GFRP composed of bonded glass/polyimide tapes and cyanate-ester/epoxy blended resin for ITER TF coils

Hemmi, Tsutomu; Nishimura, Arata*; Matsui, Kunihiro; Koizumi, Norikiyo; Nishijima, Shigehiro*; Shikama, Tatsuo*

AIP Conference Proceedings 1574, p.154 - 161, 2014/01

 Times Cited Count:3 Percentile:86.67

Japan Atomic Energy Agency (JAEA), as Japan Domestic Agency, has responsibility to procure 9 ITER Toroidal Field (TF) coils. The insulation system of the ITER TF coils consists of 3 layers of insulations, which are a conductor insulation, a double-pancake (DP) insulation and a ground insulation, composed of multi-layer glass/polyimide tapes impregnated a resin. The ITER TF coils are required to withstand an irradiation of 10 MGy from $$gamma$$-ray and neutrons since the ITER TF coils is exposed by first neutron ($$>$$ 0.1 MeV) of 10$$^{22}$$ n/m$$^{2}$$ during the operation of 20 years in the ITER. Cyanate-ester/epoxy blended resins and bonded glass/polyimide tapes are developed as insulation materials to realize the required radiation-hardness for the insulation of the ITER TF coils. To evaluate the radiation-hardness of the developed insulation materials, the inter-laminar shear strength of glass-fiber reinforced plastics (GFRP) fabricated using developed insulation materials is measured as one of most important mechanical properties before/after the irradiation in a fission reactor of JRR-3. As a result, it is demonstrated that the GFRPs using the developed insulation materials have a sufficient performance to apply the ITER TF coil insulation.

Journal Articles

Development of small specimen test techniques for the IFMIF test cell

Wakai, Eiichi; Kim, B. J.; Nozawa, Takashi; Kikuchi, Takayuki; Hirano, Michiko*; Kimura, Akihiko*; Kasada, Ryuta*; Yokomine, Takehiko*; Yoshida, Takahide*; Nogami, Shuhei*; et al.

Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 6 Pages, 2013/03

Journal Articles

Feasibility study on cryogenic irradiation facility in JMTR

Inaba, Yoshitomo; Tsuchiya, Kunihiko; Shikama, Tatsuo*; Nishimura, Arata*; Kawamura, Hiroshi

Fusion Engineering and Design, 86(2-3), p.134 - 140, 2011/03

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

The Japan Materials Testing Reactor (JMTR) of the Japan Atomic Energy Agency is a testing reactor with first criticality in March 1968. The reactor has been utilized for various neutron irradiation tests on nuclear fuels and materials, as well as for radioisotope production. The operation of JMTR stopped temporarily in August 2006 for refurbishment and improvement. The renewed JMTR will resume operation in Japanese fiscal year 2011. For the resumption of the new JMTR, the new irradiation facilities, the usability improvements, the target, and the expected roles of the new JMTR have been discussed. As one of the new irradiation facilities, the cryogenic irradiation facility, which is used for the investigation on the low-temperature irradiation behavior of materials such as superconducting magnet materials for fusion reactors, has been desired. In this study, the feasibility of low-temperature irradiation tests with the cryogenic irradiation facility was investigated, and the conceptual design of the facility was carried out. As a result, it was found that irradiation tests at temperatures below 20 K for the development of the superconducting magnet materials can be realized by the installation of an irradiation capsule into an irradiation hole with low $$gamma$$ heating and by the adoption of vacuum jacketed tubes to connect between the capsule and a cooling system.

Journal Articles

Status of Japanese design and validation activities of test facilities in IFMIF/EVEDA

Wakai, Eiichi; Kikuchi, Takayuki; Kogawara, Takafumi; Kimura, Haruyuki; Yokomine, Takehiko*; Kimura, Akihiko*; Nogami, Shuhei*; Kurishita, Hiroaki*; Saito, Masahiro*; Nishimura, Arata*; et al.

Proceedings of 23rd IAEA Fusion Energy Conference (FEC 2010) (CD-ROM), 6 Pages, 2011/03

Japanese activities of test facilities in IFMIF-EVEDA (International Fusion Materials Irradiation Facility-Engineering Validation and Engineering Design Activities) project have three subjects of engineering design of post irradiation examination (PIE) facilities, small specimen test technique (SSTT), and engineering design of high flux test module (HFTM), and this paper is summarized about present status. Functional analysis and design of 2-D and 3-D models of PIE facility were performed. In HFTM, as materials of heater, W-3Re alloy and/or SiC/SiC composite were selected in the points of high temperature materials, fabrication technology and some suitable properties such as resistance of thermal shock, high temperature re-crystallization, ductility, resistance of irradiation degradation, and low-activation. In SSTT, a test machine of fracture toughness was designed and developed for small specimens with 10 mm square, and it had high accuracy controllability for stress and displacement.

Journal Articles

Fission neutron irradiation effect on interlaminar shear strength of cyanate ester resin GFRP at RT and 77 K

Nishimura, Arata*; Izumi, Yoshinobu*; Nishijima, Shigehiro*; Hemmi, Tsutomu; Koizumi, Norikiyo; Takeuchi, Takao*; Shikama, Tatsuo*

AIP Conference Proceedings 1219, p.127 - 134, 2010/04

 Times Cited Count:1 Percentile:53.11

A GFRP with cyanate ester resin was fabricated and neutron irradiation tests up to 1$$times$$10$$^{22}$$ n/m$$^{2}$$ of fast neutron with over 0.1 MeV energy were carried out in fission reactor. The fabrication process of cyanate ester GFRP was established and a collaboration network to perform investigations on irradiation effect of superconducting magnet materials was constructed. Three kinds of samples were fabricated. The first was CTD403 GFRP made by NIFS, the second was (cyanate ester + epoxy) GFRP provided by Toshiba, and the last was CTD403 GFRP made by Toshiba. The irradiation was carried out at JRR-3 in Japan Atomic Energy Agency using Rabbit capsules. After the irradiation, short beam tests were conducted at room temperature and 77 K and interlaminar shear strength (ILSS) was evaluated. The irradiation of 1$$times$$10$$^{21}$$ n/m$$^{2}$$ increased ILSS a little but 1$$times$$10$$^{22}$$ n/m$$^{2}$$ irradiation decreased ILSS to around 50 MPa. These tendencies were observed in all three kinds of GFRPs.

Journal Articles

JSME construction standard for superconducting magnet of fusion facility "Material"

Nishimura, Arata*; Nakajima, Hideo

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 8 Pages, 2009/07

Japan Atomic Energy Agency (JAEA) has contributed to development of the structural standard for superconducting magnets entitled "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2009. This code consists of 7 sections, such as general requirements including quality assurance, material, design, fabrication (welding), non-destructive examination, pressure and leak test, and terminology. This paper describes technical contents on material section of the code. The feature of the code is to specify cryogenic materials such as JJ1, which was newly developed by JAEA, and 316LN, which is calcified by the carbon and nitrogen (C+N) contents. The design strengths from room temperature to cryogenic temperature of these materials are given in a quadratic function when the materials are as-solution heat-treated.

Journal Articles

JSME construction standard for superconducting magnet of fusion facility "Quality assurance"

Suzuki, Tetsuya*; Nishimura, Arata*; Nakajima, Hideo

Proceedings of 2009 ASME Pressure Vessels and Piping Division Conference (PVP 2009) (CD-ROM), 4 Pages, 2009/07

Japan Atomic Energy Agency (JAEA) has contributed to development of the structural standard for superconducting magnets entitled "Codes for Fusion Facilities - Rules on Superconducting Magnet Structure (2008)" issued by the Japan Society of Mechanical Engineers (JSME) in October 2009. This code consists of 7 sections, such as general requirements including quality assurance, material, design, fabrication (welding), non-destructive examination, pressure and leak test, and terminology. This paper describes technical contents on quality assurance section of the code. Quality assurance requirement consists of 18 articles such as organization, quality assurance program, design control, document control etc. Each article is designed to constitute simplified performance based requirement. In conformity assessment, realistic Qualified Inspection and Design Certification are pursued, considering the legislation, infrastructure and prospective user of standard in Japan. Role and responsibility of Qualified Inspector and Standard-Expert Engineer are newly defined in the code.

Journal Articles

Development of insulation technology with cyanate ester resins for ITER TF coils

Hemmi, Tsutomu; Koizumi, Norikiyo; Matsui, Kunihiro; Okuno, Kiyoshi; Nishimura, Arata*; Sakai, Masahiro*; Asano, Shiro*

Fusion Engineering and Design, 84(2-6), p.923 - 927, 2009/06

 Times Cited Count:14 Percentile:70.47(Nuclear Science & Technology)

The insulation for ITER-TF coils is required to withstand a total radiation dose of 10$$^{22}$$ fast n/m$$^{2}$$. For this purpose, cyanate ester resins with high radiation-resistant have been considered instead of epoxy resins. In order to evaluate an applicability of cyanate ester resins for ITER-TF coils, the developments of the vacuum pressure impregnation technology and evaluation of the high radiation-resistant properties have been carried out. This paper presents results of these developments with the cyanater ester resin.

Journal Articles

Evaluation of bending strain dependence of critical current of Nb$$_{3}$$Al conductor for coils with react-and-wind method

Kizu, Kaname; Tsuchiya, Katsuhiko; Shimada, Katsuhiro; Ando, Toshinari*; Hishinuma, Yoshimitsu*; Koizumi, Norikiyo; Matsukawa, Makoto; Miura, Yushi*; Nishimura, Arata*; Okuno, Kiyoshi; et al.

Fusion Engineering and Design, 82(5-14), p.1493 - 1499, 2007/10

 Times Cited Count:3 Percentile:26.87(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Change in properties of superconducting magnet materials by fusion neutron irradiation

Nishimura, Arata*; Nishijima, Shigehiro*; Takeuchi, Takao*; Nishitani, Takeo

Fusion Engineering and Design, 82(5-14), p.1555 - 1560, 2007/10

 Times Cited Count:5 Percentile:39.35(Nuclear Science & Technology)

Recent researches on fusion reactor show neutron streaming from ports to outside of plasma vacuum vessels and neutron penetration through blanket and a neutron shielding structure. Therefore, superconducting magnet system in a fusion reactor will be irradiated by high energy particles. To evaluate the irradiation effect of fusion neutron on the superconducting magnet materials, a cryo-target system was constructed and installed at FNS/JAEA. The Nb$$_{3}$$Sn, Nb$$_{3}$$Al samples and copper wires were cooled down to 4.5 K by a GM refrigerator and irradiation tests by 14 MeV neutron at cryogenic temperature were carried out. Change in electric resistance and critical temperatures were measured after irradiation. On the outside of the cryostat, GFRP and other sensors were arranged and irradiated at the same time. After the irradiation, the properties of those materials were investigated and the difference was discussed.

Journal Articles

Summary

Nishimura, Arata*; Okuno, Kiyoshi

Purazuma, Kaku Yugo Gakkai-Shi, 83(1), p.55 - 56, 2007/01

This paper summarizes the results obtained in the development of materials that compose superconducting magnets for fusion devices. The materials include superconductor, insulators and cryogenic steels. These relate to not only superconducting technology, but also mechanical engineering, material science, neutron engineering and plasma physics. The integration of expertise in these research fields is necessary and important to develop design of fusion devices and to perform development work.

Journal Articles

Overview of national centralized tokamak program; Mission, design and strategy to contribute ITER and DEMO

Ninomiya, Hiromasa; Akiba, Masato; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hayashi, Nobuhiko; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Inoue, Nobuyuki; et al.

Journal of the Korean Physical Society, 49, p.S428 - S432, 2006/12

To contribute DEMO and ITER, the design to modify the present JT-60U into superconducting coil machine, named National Centralized Tokamak (NCT), is being progressed under nationwide collaborations in Japan. Mission, design and strategy of this NCT program is summarized.

Journal Articles

Effects of tensile and compressive strain on critical currents of Nb$$_{3}$$Al strand and cable-in-conduit conductor

Kizu, Kaname; Tsuchiya, Katsuhiko; Shimada, Katsuhiro; Ando, Toshinari*; Hishinuma, Yoshimitsu*; Koizumi, Norikiyo; Matsukawa, Makoto; Miura, Yushi*; Nishimura, Arata*; Okuno, Kiyoshi; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.872 - 875, 2006/06

 Times Cited Count:1 Percentile:12.39(Engineering, Electrical & Electronic)

no abstracts in English

Journal Articles

Internally Cu-stabilized RHQT Nb$$_{3}$$Al superconductors with Ta matrix

Takeuchi, Takao*; Tagawa, Kohei*; Noda, Tetsuji*; Banno, Nobuya*; Iijima, Yasuo*; Kikuchi, Akihiro*; Kitaguchi, Hitoshi*; Kosuge, Michio*; Tsuchiya, Kiyosumi*; Koizumi, Norikiyo; et al.

IEEE Transactions on Applied Superconductivity, 16(2), p.1257 - 1260, 2006/06

 Times Cited Count:6 Percentile:38.57(Engineering, Electrical & Electronic)

Next generation nuclear fusion magnets would require a high-current conductor in fields more than 16 T. A CIC conductor of the rapid RHQT processed Nb$$_{3}$$Al may be a promising candidate. Good deformability of intermediately-formed bcc supersaturated-solid solution indeed allowed fabricating such a CIC conductor, which would be subsequently transformation annealed. Ag has been internally included as a basic constituent of a round strand so far, because Ag is almost non-reactive with Nb matrix during the RHQ. However, both of Ag and Nb are not suitable nuclei from the viewpoint of radioactivity when irradiated with neutrons. Recently, we have succeeded in replacing the Nb matrix with Ta that has the advantage of shorter half-life of radioactivity. In the present study, an attempt has been made to replace the Ag internal stabilizer with Cu, in the aim of further reducing radioactivity, based on anticipation that Ta would be less reactive with Cu than Nb did.

Journal Articles

Overview of the national centralized tokamak programme

Kikuchi, Mitsuru; Tamai, Hiroshi; Matsukawa, Makoto; Fujita, Takaaki; Takase, Yuichi*; Sakurai, Shinji; Kizu, Kaname; Tsuchiya, Katsuhiko; Kurita, Genichi; Morioka, Atsuhiko; et al.

Nuclear Fusion, 46(3), p.S29 - S38, 2006/03

 Times Cited Count:13 Percentile:44.28(Physics, Fluids & Plasmas)

The National Centralized Tokamak (NCT) facility program is a domestic research program for advanced tokamak research to succeed JT-60U incorporating Japanese university accomplishments. The mission of NCT is to establish high beta steady-state operation for DEMO and to contribute to ITER. The machine flexibility and mobility is pursued in aspect ratio and shape controllability, feedback control of resistive wall modes, wide current and pressure profile control capability for the demonstration of the high-b steady state.

Journal Articles

Engineering design and control scenario for steady-state high-beta operation in national centralized tokamak

Tsuchiya, Katsuhiko; Akiba, Masato; Azechi, Hiroshi*; Fujii, Tsuneyuki; Fujita, Takaaki; Fujiwara, Masami*; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; et al.

Fusion Engineering and Design, 81(8-14), p.1599 - 1605, 2006/02

 Times Cited Count:1 Percentile:10.64(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Nuclear technology and potential ripple effect of superconducting magnets for fusion power plant

Nishimura, Arata*; Muroga, Takeo*; Takeuchi, Takao*; Nishitani, Takeo; Morioka, Atsuhiko

Fusion Engineering and Design, 81(8-14), p.1675 - 1681, 2006/02

 Times Cited Count:3 Percentile:25.6(Nuclear Science & Technology)

In a fusion reactor plant, a neutral beam injector (NBI) will be operated for a long time, and it will allow neutron streaming from NBI ports to outside of the plasma vacuum vessel. It requires the superconducting magnet to develop nuclear technology to produce stable magnetic field and to reduce activation of the magnet components. In this report, the back ground of the necessity and the contents of the nuclear technology of the superconducting magnets for fusion application are discussed and some typical investigation results are presented, which are the neutron irradiation effect on Nb$$_{3}$$Sn wire, the development of low activation superconducting wire, and the design concept to reduce nuclear heating and nuclear transformation by streaming. In addition, recent activities in high energy particle physics are introduced and potential ripple effect of the technology of the superconducting magnets is described briefly.

Journal Articles

Design study of national centralized tokamak facility for the demonstration of steady state high-$$beta$$ plasma operation

Tamai, Hiroshi; Akiba, Masato; Azechi, Hiroshi*; Fujita, Takaaki; Hamamatsu, Kiyotaka; Hashizume, Hidetoshi*; Hayashi, Nobuhiko; Horiike, Hiroshi*; Hosogane, Nobuyuki; Ichimura, Makoto*; et al.

Nuclear Fusion, 45(12), p.1676 - 1683, 2005/12

 Times Cited Count:15 Percentile:48.09(Physics, Fluids & Plasmas)

Design studies are shown on the National Centralized Tokamak facility. The machine design is carried out to investigate the capability for the flexibility in aspect ratio and shape controllability for the demonstration of the high-beta steady state operation with nation-wide collaboration, in parallel with ITER towards DEMO. Two designs are proposed and assessed with respect to the physics requirements such as confinement, stability, current drive, divertor, and energetic particle confinement. The operation range in the aspect ratio and the plasma shape is widely enhanced in consistent with the sufficient divertor pumping. Evaluations of the plasma performance towards the determination of machine design are presented.

Journal Articles

Intelligible seminar on fusion reactors, 9; Superconducting coil to generate magnetic field for plasma confinement

Koizumi, Norikiyo; Nishimura, Arata*

Nihon Genshiryoku Gakkai-Shi, 47(10), p.703 - 708, 2005/10

no abstracts in English

35 (Records 1-20 displayed on this page)