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Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Inagaki, Takashi; Matsui, Kunihiro; Koizumi, Norikiyo
Fusion Engineering and Design, 109-111(Part B), p.1592 - 1597, 2016/11
Times Cited Count：7 Percentile：48.77(Nuclear Science & Technology)Japan Atomic Energy Agency (JAEA) has responsibility to procure 9 Toroidal Field (TF) coils and 19 TF coil structures for ITER. A TF coil structure consists of the main body structure having a D-shape with 16.5 m in height and 9m in width in which superconducting winding is stored and the components to connect adjacent TF coil or other ITER devices. TF coil structures are required the very tight tolerance which is less than 2 mm for the final dimension, which is quite challenging considering large size of TF coil structure. To achieve this tolerance, extra material will be put on the each material, and machining must be performed after welding. It is important to figure out detail welding deformation and reducing the machining process to optimize manufacturing. JAEA performed an additional manufacturing trial of A1 segment which is part of TF coil structure. JAEA adopted balance welding instead of using strong restriction jig welding in additional trial. The angular distortion of previous result was +6.5/+8.9mm, however angular distortions of latest trial were -3.0/+1.6mm (right side) and 0.0/+2.4mm (left side). This progress shows that welding deformation could be controlled closer in the target value (0.0 mm) than previous method applied. Based on latest knowledge, JAEA started actual TF coil structure manufacturing from April 2014. Actual manufacturing is steadily progressing with development process improvement by learning effect and improvement of manufacturing sequence.
Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Saito, Toru; Koizumi, Norikiyo
IEEE Transactions on Applied Superconductivity, 26(4), p.4204705_1 - 4204705_5, 2016/06
Japan Atomic Energy Agency (JAEA) has responsibility to procure 9 Toroidal Field (TF) coils and 19 TF coil structures for ITER project. A TF coil structure consists of the main body structure having D-shape with 13.6 m of height and 9 m of width in which a superconducting winding pack is enclosed and the components to connect adjacent TF coils or other surrounding components. TF coil structures are manufactured from austenitic stainless steel having high tensile strength and fracture toughness at cryogenic temperature (4K) in order to ensure the huge electromagnetic force. As structural materials, austenitic stainless steel having high Manganese and Nitrogen which was named as JJ1 and high Nitrogen containing 316LN stainless steel are applied. These materials are welded each other by Tungsten Inert Gas (TIG) welding with FMYJJ1, which had been developed for welding material based on JJ1. The cryogenic mechanical properties of welded joints which have over 200 mm of actual thickness are limited due to less demonstration of such a heavy thick joints. In addition, destructive test specimens cannot be taken from actual TF coil structure. Hence, it is necessary to confirm actual thickness of welded joint performance by actual welding conditions mock-up. JAEA manufactured some welded joint mock-ups having the same welding thickness and combination of base materials as actual TF coil structure by applying actual welding conditions. JAEA measured mechanical properties of tensile and fracture toughness in liquid Helium environment by using test specimens taken from these welded joint mock-ups. This study reports these mechanical test results of welded joints at cryogenic temperature. "The view and opinions expressed herein do not necessarily reflect those of the ITER Organization."
Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Saito, Toru*; Morimoto, Masaaki*; Inagaki, Takashi*; Hong, Y.-S.*; Matsui, Kunihiro; Hemmi, Tsutomu; Kajitani, Hideki; et al.
Physics Procedia, 67, p.536 - 542, 2015/07
Times Cited Count：5 Percentile：81.72(Physics, Applied)Japan Atomic Energy Agency (JAEA) has developed the tensile strength prediction method at liquid helium temperature (4K) using the quadratic curve as a function of the content of carbon and nitrogen in order to establish the rationalized quality control of the austenitic stainless steel used in the ITER superconducting coil operating at 4K. ITER is under construction aiming to verify technical demonstration of a nuclear fusion generation. Toroidal Field Coil (TFC), one of superconducting system in ITER, have been started procurement of materials in 2012. JAEA is producing materials for actual product which are the forged materials with shape of rectangle, round bar, asymmetry and etc. JAEA has responsibility to procure all ITER TFC Structures. In this process, JAEA obtained many tensile strength of both room temperature and 4K about these structural materials, for example, JJ1: High manganese stainless steel for structure (0.03C-12Cr-12Ni-10Mn-5Mo- 0.24N) and 316LN: High nitrogen containing stainless steel (0.2Nitrogen). Based on these data, accuracy of 4K strength prediction method for actual TFC Structure materials was evaluated and reported in this study.
Sn cable assembled with conduit for ITER central solenoidNabara, Yoshihiro; Suwa, Tomone; Takahashi, Yoshikazu; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Sakurai, Takeru; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; et al.
IEEE Transactions on Applied Superconductivity, 25(3), p.4200305_1 - 4200305_5, 2015/06
Times Cited Count：0 Percentile：0.00(Engineering, Electrical & Electronic)Iguchi, Masahide; Sakurai, Takeru; Nakahira, Masataka; Koizumi, Norikiyo; Nakajima, Hideo
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 6 Pages, 2015/05
Application of partial penetration welding (PPW) to ITER Toroidal Field Coil structure has been proposed because of limited accessability for weld due to complex geometry and low stress and low importance components. In order to obtain fatigue crack growth (FCG) behavior of PPW joint in cryogenic environment, Japan Atomic Energy Agency performed FCG test at 4K by using Compact Tension (CT) specimens having as-weld notch of PPW. These CT specimens were made from mockups having one of actual joint shape of PPW, double J-groove. As the result of this test, it was observed that crack propagated in weld metal having inclination from as-weld notch. Moreover it was shown that FCG rate of as-weld CT specimens had high FCG rate region in early stage of crack propagation due to residual stress distribution. In addition, application method of this FCG rate to designing of PPW joint was proposed and verified in this study.
Oshikawa, Takumi*; Funakoshi, Yoshihiko*; Imaoka, Hiroshi*; Yoshikawa, Kohei*; Maari, Yasutaka*; Iguchi, Masahide; Sakurai, Takeru; Nakahira, Masataka; Koizumi, Norikiyo; Nakajima, Hideo
Proceedings of 19th International Forgemasters Meeting (IFM 2014), p.254 - 259, 2014/09
ITER is a large-scale experiment that aims to demonstrate that it is possible to produce commercial energy from fusion. ITER Toroidal Field Coil Case (hereinafter referred to as "ITER TFCC") is one of the important components of ITER. The ITER TFCC materials are made of high nitrogen austenitic stainless steel and having various configurations. The ITER TFCC material which manufactured by JCFC has a complex configuration with heaver thickness than other materials. It is difficult to form near net shape to delivery configuration by ordinary open die forging method such as upset and stretching, because the ITER TFCC materials manufactured by JCFC have a complex configuration. Therefore ingot weight and lead time of machining increase when ITER TFCC materials are forged by ordinary open die forging method. Moreover, in order to get good attenuation at Ultrasonic examination, it is necessarily to make fine and uniform grain of the material. However, it is impossible to control grain size of austenitic stainless steel by heat treatment. The grain becomes fine and uniform by only forging process with suitable condition. Therefore, JCFC has studied suitable forging method to become near net shape to delivery configuration and also to get fine grain of center of the material. Based on these result, ITER TFCC materials were manufactured. This innovative forging process led to reduce the weight of ingot compared with general forging. And it had good Ultrasonic attenuation. It was confirmed that the results of material test and nondestructive examination satisfied the requirements of Japan domestic agency (hereinafter referred to as "JADA"). Moreover, the test coupons were taken from center of thick part of product and used for various tests. As the result of tests, it was confirmed that results of material test satisfied the requirements of JADA. It is clear that this innovative forging method is very suitable process for manufacturing of ITER TFCC materials.
Nabara, Yoshihiro; Suwa, Tomone; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Sakurai, Takeru; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; et al.
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Sn superconductor for ITER CS coilNabara, Yoshihiro; Suwa, Tomone; Hemmi, Tsutomu; Kajitani, Hideki; Ozeki, Hidemasa; Sakurai, Takeru; Iguchi, Masahide; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; et al.
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Koizumi, Norikiyo; Nakahira, Masataka; Matsui, Kunihiro; Hemmi, Tsutomu; Kajitani, Hideki; Sakurai, Takeru; Takano, Katsutoshi; Yamane, Minoru; Ando, Shinji
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Sakurai, Eiko*; Sakurai, Eiichi*; Ishii, Keizo*; Koshio, Shigeki*; Ito, Shun*; Matsuyama, Shigeo*; Koka, Masashi; Yamada, Naoto; Kitamura, Akane; Sato, Takahiro; et al.
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Nabara, Yoshihiro; Suwa, Tomone; Ozeki, Hidemasa; Sakurai, Takeru; Kajitani, Hideki; Iguchi, Masahide; Hemmi, Tsutomu; Nunoya, Yoshihiko; Isono, Takaaki; Matsui, Kunihiro; et al.
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Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Matsui, Kunihiro; Hemmi, Tsutomu; Kajitani, Hideki; Koizumi, Norikiyo
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Nabara, Yoshihiro; Suwa, Tomone; Ozeki, Hidemasa; Sakurai, Takeru; Kajitani, Hideki; Iguchi, Masahide; Hemmi, Tsutomu; Shimono, Mitsugu; Ebisawa, Noboru; Sato, Minoru; et al.
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Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Morimoto, Masaaki; Inagaki, Takashi; Tanaka, Nobuhiko; Hong, Y.-S.*; Koizumi, Norikiyo
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Iguchi, Masahide; Sakurai, Takeru; Morimoto, Masaaki*; Hong, Y.-S.*; Inagaki, Takashi; Tanaka, Nobuhiko; Nakahira, Masataka; Hemmi, Tsutomu; Matsui, Kunihiro; Koizumi, Norikiyo
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Sakurai, Takeru; Iguchi, Masahide; Saito, Toru; Nakahira, Masataka
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Iguchi, Masahide; Sakurai, Takeru; Inagaki, Takashi; Tanaka, Nobuhiko; Hwang, S.*; Ino, Masanobu; Nakahira, Masataka; Hemmi, Tsutomu; Matsui, Kunihiro; Koizumi, Norikiyo
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Sakurai, Takeru; Iguchi, Masahide; Nakahira, Masataka; Minemura, Toshiyuki*; Yanagi, Yutaka*; Osemochi, Koichi*
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