Mass production of NbSn conductors for ITER toroidal field coils in Japan

Takahashi, Yoshikazu; Isono, Takaaki; Hamada, Kazuya; Nunoya, Yoshihiko; Nabara, Yoshihiro; Matsui, Kunihiro; Hemmi, Tsutomu; Kawano, Katsumi; Koizumi, Norikiyo; Oshikiri, Masayuki; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4801904_1 - 4801904_4, 2012/06

https://doi.org/10.1109/TASC.2011.2178053

Japan Atomic Energy Agency is the first to start the mass production of the TF conductors in Phase IV in March 2010 among the 6 parties who are procuring TF conductors in the ITER project. The conductor is cable-in-conduit conductor with a central spiral. A total of 900 NbSn strands and 522 copper strands are cabled around the central spiral and then wrapped with stainless steel tape whose thickness is 0.1 mm. Approximately 60 tons of NbSn strands were manufactured by the two suppliers in December 2010. This amount corresponds to approximately 55% of the total contribution from Japan. Approximately 30% of the total contribution from Japan was completed as of February 2011. JAEA is manufacturing one conductor per month under a contract with two Japanese companies for strands, one company for cabling and one company for jacketing. This paper summarizes the technical developments including a high-level quality assurance. This progress is a significant step in the construction of the ITER machine.

Development of structures for ITER toroidal field coil in Japan

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

https://doi.org/10.1109/TASC.2011.2177795

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.

Trial fabrication of one-third scale double pancake of ITER toroidal field coil

Matsui, Kunihiro; Koizumi, Norikiyo; Hemmi, Tsutomu; Takano, Katsutoshi; Nakajima, Hideo; Kimura, Satoshi*; Iijima, Ami*; Sakai, Masahiro*; Osemochi, Koichi*; Shimada, Mamoru*

IEEE Transactions on Applied Superconductivity, 22(3), p.4203005_1 - 4203005_5, 2012/06

https://doi.org/10.1109/TASC.2011.2178379

JAEA is responsible for the procurement of 9 toroidal field (TF) coils as Japanese Domestic Agency. JAEA had started several trials to successfully develop technologies for the TF coil manufacture since March 2009, and performed one-third scale trials aiming at qualifying and optimizing the procedures of the TF coil fabrication. The fabricated double pancakes (DPs) were successfully put into the profile with tolerances from zero to 1.5 mm. These tolerances correspond to 0.06% accuracy in the conductor length. The geometry of the DP was changed after heat treatment. Heat treatment procedure to avoid such deformation should be developed or the change of winding geometry should be taken into account in the fabrication of the TF coils. The one-third scale DP was successfully impregnated. Although exothermal reaction is given to take place during curing in the blended resin, we successfully cured the one-third scale DP.

Strain and magnetic-field characterization of a bronze-route NbSn ITER wire; Benchmarking of strain measurement facilities at NIST and University of Twente

Cheggour, N.*; Nijhuis, A.*; Krooshoop, H. J. G.*; Lu, X. F.*; Splett, J.*; Stauffer, T. C.*; Goodrich, L. F.*; Jewell, M. C.*; Devred, A.*; Nabara, Yoshihiro

IEEE Transactions on Applied Superconductivity, 22(3), p.4805104_1 - 4805104_4, 2012/06

https://doi.org/10.1109/TASC.2011.2177433

A benchmarking experiment was conducted to compare strain measurement facilities at the National Institute of Standards and Technology (NIST) and the University of Twente. The critical current of a bronze-route NbSn ITER wire was measured as a function of axial strain and magnetic field in liquid helium temperature at both institutes. NIST used a Walters' spring strain device and University of Twente used a Pacman apparatus. The ITER bronze-route wire investigated had a very high irreversible strain limit and allowed the comparison of data over a wide range of applied strain from to . A full account of the data analysis and comparisons will be presented. Measurement protocols and parameterization procedures will also be discussed.

Influence of wire parameters on critical current versus strain characteristics of bronze processed NbSn superconducting wires

Miyatake, Takayuki*; Murakami, Yukinobu*; Kurahashi, Hidefumi*; Hayashi, Seiji*; Zaitsu, Kyoji*; Seeber, B.*; Mondonico, G.*; Nabara, Yoshihiro

IEEE Transactions on Applied Superconductivity, 22(3), p.4805005_1 - 4805005_5, 2012/06

https://doi.org/10.1109/TASC.2011.2179697

In order to develop bronze processed NbSn strands for ITER TF and CS coils, the influences of various parameters of NbSn strands such as filament diameter, barrier materials, barrier thickness, heat treatment pattern and Ti addition on critical current () vs. axial strain characteristics were investigated. The change of theses parameters brought significant changes to superconducting properties involving and n-value at zero applied strain. In spite of different strand parameters, the strain dependency of normalized was almost the same, except for Ti-addition affecting the critical field . Based on the results, bronze processed NbSn strands with non-Cu critical current density more than 1,100 A/mm at 12T, 4.2K have been successfully developed for the CS coil.

Development of ITER TF coil in Japan

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

https://doi.org/10.1109/TASC.2011.2176697

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.

Manufacture of the winding pack and development of key parts for the JT-60SA poloidal field coils

Tsuchiya, Katsuhiko; Kizu, Kaname; Murakami, Haruyuki; Yoshida, Kiyoshi; Kurihara, Kenichi; Hasegawa, Mitsuru*; Kuno, Kazuo*; Nomoto, Kazuhiro*; Horii, Hiroyuki*

IEEE Transactions on Applied Superconductivity, 22(3), p.4202304_1 - 4202304_4, 2012/06

https://doi.org/10.1109/TASC.2011.2178056

no abstracts in English

Addressing the technical challenges for the construction of the ITER Central Solenoid

Libeyre, P.*; Bessette, D.*; Jewell, M.*; Jong, C.*; Lyraud, C.*; Rodriguez-Mateos, M.*; Hamada, Kazuya; Reiersen, W.*; Martovetsky, N.*; Rey, C.*; et al.

IEEE Transactions on Applied Superconductivity, 22(3), p.4201104_1 - 4201104_4, 2012/06

https://doi.org/10.1109/TASC.2011.2178054

The Central Solenoid (CS) of the ITER magnet system will play a major role in tokamak operation, providing not only the major part of the inductive flux variation required to drive the plasma but also contributing to the shaping of the field lines and to vertical stability control. To meet these requirements, the design has been optimised by splitting the CS into six independently powered coils enclosed inside an external structure which provides vertical precompression thus preventing separation of the coils and, additionally, acting as a support to net resulting loads. To ensure that the CS design meets the ITER criteria, several analyses are performed along with a series of R&D trials to qualify the technologies to be used for the manufacture of the conductor, the coils and the structure.

High magnetic field for material science; Quantum beam materials science view point

Kakurai, Kazuhisa; Nojiri, Hiroyuki*

no journal, ,