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Kobayashi, Kazuhiro; Torikai, Yuji*; Saito, Makiko; Alimov, V. Kh.*; Miya, Naoyuki; Ikeda, Yoshitaka
Fusion Science and Technology, 67(2), p.428 - 431, 2015/03
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)Disassembly of the JT-60U torus was started in 2010 after 18 years deuterium operations. In the disassembly of the JT-60U torus, tritium retention in the vacuum vessel of the JT-60U is one of the most important safety issues for the fusion reactor. It was very important to study the tritium behavior in Inconel 625 from viewpoint of the clearance procedure in the future plan. After the tritium release for about 1 year at 298 K, the residual tritium in the specimen was released by heating up to 1073 K, and then the residual tritium in the specimen was measured by chemical etching method. Most of the chemical form of the released tritium was HTO. The contaminated specimen by tritium was released continuously the diffusible tritium under the ambient condition. In the tritium release experiment, most of tritium in the specimen was released during 1 year.
Nishiyama, Tomokazu; Miyo, Yasuhiko; Okano, Fuminori; Sasajima, Tadayuki; Ichige, Hisashi; Kaminaga, Atsushi; Miya, Naoyuki; Sukegawa, Atsuhiko; Ikeda, Yoshitaka; Sakasai, Akira
JAEA-Technology 2014-006, 30 Pages, 2014/03
JAEA-Technology-2014-006.pdf:4.87MB
JT-60 tokamak device and the peripheral equipment were disassembled so as to be upgraded to the superconducting tokamak JT-60SA. The disassembled components were stored into storage and airtight containers at the radioactive control area. The total weight and the total number of those components are about 1,100 tons and about 11,500 except for large components. Radiation measurements and records of the radioactive components were required one by one under the law of Act on Prevention of Radiation Disease Due to Radioisotopes, etc. for the control of transport and storage from the radioactive control area to the other area. The storage management of the radioactive components was implemented by establishing the work procedure and the component management system by barcode tags. The radioactive components as many as 11,500 were surely and effectively stored under the law. The report gives the outline of the storage of JT-60 radioactive components by the storage containers.
Sukegawa, Atsuhiko; Miya, Naoyuki; Oikawa, Akira
Proceedings of 19th International Conference on Nuclear Engineering (ICONE-19) (CD-ROM), 8 Pages, 2011/10
The radioactivities on the materials of JT-60U fusion device, which decommissioning is underway toward the upgraded superconducting tokamak machine, have been evaluated by calculation and measurements on the specimens of the structure materials and the components. In the induced activities on those materials, the highest activation on the material was stainless steel. The essential nuclide was 
Co in the stainless steels. The stainless steel 316 of about 35 tons constitutes the base of interiorities as a first wall on the vacuum vessel in JT-60U. For the management of radioactive materials, the evaluation for the steels with the activated nuclides is important. The activated structure materials are kept in the controlled area in the JT-60 facilities, according to the criteria for handling activated materials by the defined domestic government.
Nishiyama, Tomokazu; Okano, Fuminori; Miyo, Yasuhiko; Kubo, Hirotaka; Miya, Naoyuki; Oikawa, Akira; Sasajima, Tadayuki; Sakasai, Akira
Heisei-22-Nendo Kumamoto Daigaku Sogo Gijutsu Kenkyukai Hokokushu (CD-ROM), 5 Pages, 2011/03
no abstracts in English
Matsukawa, Makoto; Kikuchi, Mitsuru; Fujii, Tsuneyuki; Fujita, Takaaki; Hayashi, Takao; Higashijima, Satoru; Hosogane, Nobuyuki; Ikeda, Yoshitaka; Ide, Shunsuke; Ishida, Shinichi; et al.
Fusion Engineering and Design, 83(7-9), p.795 - 803, 2008/12
Times Cited Count：17 Percentile：72.86(Nuclear Science & Technology)no abstracts in English
Masaki, Kei; Tanabe, Tetsuo*; Hirohata, Yuko*; Oya, Yasuhisa*; Shibahara, Takahiro*; Hayashi, Takao; Sugiyama, Kazuyoshi*; Arai, Takashi; Okuno, Kenji*; Miya, Naoyuki
Nuclear Fusion, 47(11), p.1577 - 1582, 2007/11
Times Cited Count：14 Percentile：45.18(Physics, Fluids & Plasmas)In JT-60U, erosion/deposition analyses for the plasma facing wall have shown that deposition was dominant at the inner-middle first wall and the inner divertor, whereas erosion dominant at the upper first wall and the outer divertor. Assuming toroidal symmetry in the erosion and deposition patterns, the net carbon erosion and deposition in the divertor area were estimated to be 0.34 kg and 0.55 kg, respectively. In a whole, the increment of carbon in the divertor region was 0.21 kg, which should be originated from the first wall. The hydrogen concentration in the thick deposition layer of the inner divertor was 0.02 in (H+D)/C. In the plasma-shadowed area underneath the divertor region at around 420 K, re-deposited layers of 2 
m-thick were found with high hydrogen concentration of 0.8 in (H+D)/C. The carbon deposition rate in the plasma-shadowed area, however, was 8
10
atoms/s, which was one order smaller than that (610
atoms/s) on the wall surface.
Shibama, Yusuke; Arai, Takashi; Miyo, Yasuhiko; Sawai, Tomotsugu; Sakurai, Shinji; Masaki, Kei; Suzuki, Yutaka; Jitsukawa, Shiro; Miya, Naoyuki
Fusion Engineering and Design, 82(15-24), p.2462 - 2470, 2007/10
Times Cited Count：0 Percentile：0.01(Nuclear Science & Technology)The structural design of the tile as a ripple reduction for toroidal magnetic field in JT-60U was outlined. 8Cr-2W-0.2V ferritic steel plates were fabricated and mechanical and vacuum properties were evaluated to assess the design conditions. Tensile properties were uniform in yield and tensile strength at ambient temperature and sufficient strength as the structural integrity at operational temperature of 423 K and 573 K. Vacuum property was measured with the baking at 473 K and similar to the conventional stainless steel but not satisfy the JT-60 standard of the in-situ material of the vacuum vessel. The ferritic steel was judged as an installable because of that the JT-60 baking temperature is 573 K higher than this test temperature of 473 K, and of that residual out-gassing was hydrogen which was the fuel of the operational plasma.
Nakahata, Toshihiko*; Yoshikawa, Akira*; Oyaizu, Makoto*; Oya, Yasuhisa*; Ishimoto, Yuki*; Kizu, Kaname; Yagyu, Junichi; Ashikawa, Naoko*; Nishimura, Kiyohiko*; Miya, Naoyuki; et al.
Journal of Nuclear Materials, 367-370(2), p.1170 - 1174, 2007/08
Times Cited Count：3 Percentile：25.51(Materials Science, Multidisciplinary)Retention and desorption behavior of deuterium implanted into pure boron films has been studied by means of the secondary ion mass spectroscopy. It was found that the factor dominating deuterium desorption was the sample temperature. At stage 1, below 573 K, the desorption of deuterium from B-D-B bond dominated and diffusion was the rate-determining process in this stage. Above 573 K, deuterium was mainly desorbed from B-D bonds, and recombination was the rate-determining process in this stage. The effective molecular recombination rate constant of deuterium trapped as B-D bond was determined by an isothermal annealing experiment.
He, p)
He resonant nuclear reactionHayashi, Takao; Sugiyama, Kazuyoshi*; Krieger, K.*; Mayer, M.*; Alimov, V. Kh.*; Tanabe, Tetsuo*; Masaki, Kei; Miya, Naoyuki
Journal of Nuclear Materials, 363-365, p.904 - 909, 2007/06
Times Cited Count：11 Percentile：61.1(Materials Science, Multidisciplinary)The absolute concentrations and the depth profiles of deuterium in plasma-facing graphite tiles used in JT-60U were determined by means of the D(He, p)He resonant nuclear reaction. The highest deuterium concentration was found at a plasma-facing surface near the outer pumping slot on the outer dome wing tile, where redeposited layers with thicknesses in the micron or submicron range were observed, indicating deuterium codepostion with carbon. In addition, a high flux of high energy deuterium originating from NBI is expected on the outer dome wing as well as on the dome top tile, and could have some contribution to this area of highest deuterium retention. The deuterium content integrated up to about 16 m was 
2.510
D/m
. The depth profile has a broad peak in the atomic ratio of D/C0.05 at a depth of about 2.5 m. This is mainly because D retained in the top surface was replaced by H due to isotope exchange during H discharges, which were carried out to remove tritium from the plasma-facing wall before air ventilation. In erosion dominated areas such as the outer divertor tiles, the amount of deuterium was one order of magnitude lower than that on the outer dome wing tile. In the first wall area, the highest amount of deuterium with a content of 1.010 D/m was found in the upper region, nearest to the plasma. Again implantation of high energy deuterium due to NBI could have some contribution to the high deuterium retention.
Ueda, Yoshio*; Fukumoto, Masakatsu*; Nishikawa, Masahiro*; Tanabe, Tetsuo*; Miya, Naoyuki; Arai, Takashi; Masaki, Kei; Ishimoto, Yuki*; Tsuzuki, Kazuhiro*; Asakura, Nobuyuki
Journal of Nuclear Materials, 363-365, p.66 - 71, 2007/06
Times Cited Count：10 Percentile：58.16(Materials Science, Multidisciplinary)no abstracts in English
Hirohata, Yuko*; Tanabe, Tetsuo*; Oya, Yasuhisa*; Okuno, Kenji*; Masaki, Kei; Miya, Naoyuki; JT-60U Team
Journal of Nuclear Materials, 363-365, p.854 - 861, 2007/06
Times Cited Count：11 Percentile：61.1(Materials Science, Multidisciplinary)no abstracts in English
Ashikawa, Naoko*; Kizu, Kaname; Yagyu, Junichi; Nakahata, Toshihiko*; Nobuta, Yuji; Nishimura, Kiyohiko*; Yoshikawa, Akira*; Ishimoto, Yuki*; Oya, Yasuhisa*; Okuno, Kenji*; et al.
Journal of Nuclear Materials, 363-365, p.1352 - 1357, 2007/06
Times Cited Count：10 Percentile：58.16(Materials Science, Multidisciplinary)no abstracts in English
Sugiyama, Kazuyoshi*; Hayashi, Takao; Krieger, K.*; Mayer, M.*; Masaki, Kei; Miya, Naoyuki; Tanabe, Tetsuo*
Journal of Nuclear Materials, 363-365, p.949 - 954, 2007/06
Times Cited Count：10 Percentile：58.16(Materials Science, Multidisciplinary)no abstracts in English
Sukegawa, Atsuhiko; Oikawa, Akira; Miya, Naoyuki; Fujita, Takaaki
Proceedings of 15th International Conference on Nuclear Engineering (ICONE-15) (CD-ROM), 6 Pages, 2007/04
The low level waste of JT-60U fusion device has been estimated by a regulatory clearance. The JT-60U consists of the heating devices such as neutral beam injectors and radio frequency systems, the main devices including the vacuum vessel and the coils, and the diagnostic devices in the torus hall. Those structure materials of the JT-60U device include copper, stainless steels, carbon steel, high manganese steel, inconel 625, ferritic steel, and lead. The gross weight of the device is about 6,400 tons. Radiation transport calculations are performed using 1D code ANISN. In the activation calculations, ACT-4 was employed. The stainless steels of about 50 tons are used for the base of the first wall on the vacuum vessel in JT-60U. For the low level waste management, the evaluation for the steels with the activated nuclides is important. IAEA RS-G-1.7 is applied to the clearance level for the structures of the activated materials. The activated level of the material with Co takes about 45 years until less than the clearance level.
Masaki, Kei; Tanabe, Tetsuo*; Hirohata, Yuko*; Oya, Yasuhisa*; Shibahara, Takahiro*; Hayashi, Takao; Sugiyama, Kazuyoshi*; Arai, Takashi; Okuno, Kenji*; Miya, Naoyuki
Proceedings of 21st IAEA Fusion Energy Conference (FEC 2006) (CD-ROM), 8 Pages, 2007/03
Evaluation of fuel inventory and its retention process are critical issues for a next-step fusion device, especially with carbon-based wall. In order to resolve the issues, the hydrogen retention and carbon deposition analyses for the plasma facing surfaces and plasma-shadowed area of JT-60U have been performed. In JT-60U, erosion/deposition analyses for the plasma facing wall have shown that deposition was dominant at the inner-middle first wall and the inner divertor, whereas erosion dominant at the upper first wall and the outer divertor. Assuming toroidal symmetry in the erosion and deposition patterns, the net carbon erosion and deposition in the divertor area were estimated to be 0.34 kg and 0.55 kg, respectively. In a whole, the increment of carbon in the divertor region was 0.21 kg, which should be originated from the first wall. The hydrogen concentration in the thick deposition layer of the inner divertor was 
0.02 in (H+D)/C. In the plasma-shadowed area underneath the divertor region at around 420 K, re-deposited layers of 2m-thick were found with high hydrogen concentration of 0.8 in (H+D)/C. The carbon deposition rate in the plasma-shadowed area, however, was 810 atoms/s, which was one order smaller than that (610 atoms/s) on the wall surface.
Kimura, Haruyuki; Inutake, Masaaki*; Kikuchi, Mitsuru; Ogawa, Yuichi*; Kamada, Yutaka; Ozeki, Takahisa; Naito, Osamu; Takase, Yuichi*; Ide, Shunsuke; Nagasaki, Kazunobu*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 83(1), p.81 - 93, 2007/01
no abstracts in English
C from methane injection into outer divertor plasma in JT-60UNobuta, Yuji; Masaki, Kei; Arai, Takashi; Sakasai, Akira; Miya, Naoyuki; Tanabe, Tetsuo*
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
no abstracts in English
Kudo, Yusuke; Sawai, Tomotsugu; Sakurai, Shinji; Masaki, Kei; Suzuki, Yutaka; Sasajima, Tadayuki; Hayashi, Takao; Takahashi, Ryukichi*; Honda, Masao; Jitsukawa, Shiro; et al.
Journal of the Korean Physical Society, 49(96), p.S297 - S301, 2006/12
Installation of ferritic steel tiles was proposed in JT-60U to reduce the toroidal magnetic field ripple and to improve the fast ion loss, which degrades heating efficiency and increases heat load on plasma facing component under large volume plasma operations. We selected a 8Cr-2W-0.2V ferritic steel with the cost-effectiveness, in which concentration limits of activation elements in F82H were relaxed because of the less number of neutron generations from deuterium operations on JT-60U. The fabricated ferritic steel has clear tempered martensitic microstructure, and sufficient magnetic and mechanical properties. The saturated magnetization was estimated to 1.7 Tesla at 573 K, lower than expected, but effectiveness in JT-60U was confirmed by numerical analyses. To research the effect of material conditions, such as microstructure and heat treatment, on saturated magnetization of the ferritic steel based on 8-9Cr is important for the future fusion reactors which will be planned to install the ferritic steel as the in-vessel components.
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.
Kizu, Kaname; Yagyu, Junichi; Ishimoto, Yuki*; Nakano, Tomohide; Tsuzuki, Kazuhiro*; Miya, Naoyuki; Ashikawa, Naoko*; Nishimura, Kiyohiko*; Sagara, Akio*
Annual Report of National Institute for Fusion Science; April 2005 - March 2006, P. 65, 2006/11
no abstracts in English
