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Nakano, Masanao; Hosomi, Kenji; Nishimura, Shusaku; Matsubara, Natsumi; Okura, Takehisa; Kuramochi, Akihiko; Kawasaki, Masatsugu; Takeuchi, Erina; Fujii, Yutaka*; Jinno, Tsukasa*; et al.
Hoken Butsuri (Internet), 55(2), p.102 - 109, 2020/06
After the Fukushima-Daiichi Nuclear Power Station (1F) Accident in March 2011, the increase was significantly observed in a part of the result of the environmental radiation monitoring in Ibaraki prefecture. "The review meeting of the environmental effect from 1F accident" was established to discuss technically the fluctuation of monitoring data. The review meeting collected the monitoring data from the four nuclear operators, and discussed a fluctuating trend, 
Cs/
Cs activity ratio, and so on. In this report, the results of the dose rate and Cs in fallout, surface soil, flatfish and seabed sediment are introduced. Also the problem solving in the review meeting is introduced.
Nakamura, Kazuo*; Jiang, Y.*; Liu, X.*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Hasegawa, Makoto*; Tokunaga, Kazutoshi*; Zushi, Hideki*; et al.
Fusion Engineering and Design, 86(6-8), p.1080 - 1084, 2011/10
Times Cited Count：4 Percentile：32.59(Nuclear Science & Technology)Higashijima, Satoru; Sakurai, Shinji; Sakasai, Akira
Journal of Nuclear Materials, 417(1-3), p.912 - 915, 2011/10
Times Cited Count：9 Percentile：57.01(Materials Science, Multidisciplinary)JT-60SA divertor has to receive the maximum heat flux of 
15 MW/m
for 100 s, and JAEA have developed the monoblock-type CFC divertor target for JT-60SA. For boosting the production yield of the target, CFC cracking due to thermal expansion and contraction of the CuCrZr cooling tube should be suppressed. CuCrZr characteristics strongly depend on the heat treatment, and the target is heat-treated on the manufacturing process of brazing, solution treatment, and annealing. CuCrZr test specimens were heat-treated with the targets, and the strength and the hardness of the specimens were almost the same in the case of the quenching rates of 0.65 
C/s and 1.5 C/s around 800 C. It is clarified that the slower quenching rate is acceptable, and the half of the mock-ups at least removed high heat flux of 15 MW/m as required without the CFC cracking.
Sakurai, Shinji; Higashijima, Satoru; Hayashi, Takao; Shibama, Yusuke; Masuo, Hiroshige*; Ozaki, Hidetsugu; Sakasai, Akira; Shibanuma, Kiyoshi
Fusion Engineering and Design, 85(10-12), p.2187 - 2191, 2010/08
Times Cited Count：10 Percentile：56.32(Nuclear Science & Technology)JT-60SA tokamak project has just started construction phase under both the Japanese domestic program and the Japan-EU international program "ITER Broader Approach". All of plasma facing components (PFC) shall be actively cooled due to high power long pulse plasma heating. Lower single null closed divertor with vertical target (VT) will be installed at the start of experiment phase. Each divertor module covers a 10-degree sector in toroidal direction. PFCs such as VTs, baffles and dome shall be assembled on a divertor cassette, which provides integrated coolant pipe connection to coolant headers in the VV. Static structural analysis for dead weight, coolant pressure and EM loads shows that displacement and stress of the divertor module are generally small but a part of support structure of PFC requires improvement.
Higashijima, Satoru; Sakurai, Shinji; Suzuki, Satoshi; Yokoyama, Kenji; Kashiwa, Yoshitoshi; Masaki, Kei; Shibama, Yusuke; Takechi, Manabu; Shibanuma, Kiyoshi; Sakasai, Akira; et al.
Fusion Engineering and Design, 84(2-6), p.949 - 952, 2009/06
Times Cited Count：9 Percentile：53.3(Nuclear Science & Technology)An upgrading device of JT-60 tokamak with fully superconducting coils (JT-60SA) is constructed under both the Japanese domestic program and the international program "Broader Approach". The maximum heat flux to JT-60SA divertor is estimated to 15 MW/m for 100 s, and a monoblock-type CFC divertor armor is promising. The JT-60SA armor consists of CFC monoblocks, a cooling CuCrZr screw-tube, and a thin OFHC-Cu buffer layer, and the brazed joints are essential for the armor. Metalization inside CFC monoblock is applied for further improvement, and we confirmed again that the mock-up has heat removal capability in excess of ITER requirement. For optimization of the fabrication method and understanding of the production yield, the mock-ups corresponding to quantity produced in one furnace is also produced, and the half of the mock-ups could remove 15 MW/m as required. This summarizes the recent progress of design and mock-up test results for JT-60SA divertor armor.
Sakurai, Shinji; Kawashima, Hisato; Higashijima, Satoru; Shimizu, Katsuhiro; Masaki, Kei; Asakura, Nobuyuki; Shibama, Yusuke; Sakasai, Akira
Journal of Nuclear Materials, 390-391, p.891 - 894, 2009/06
Times Cited Count：1 Percentile：10.22(Materials Science, Multidisciplinary)The entire plasma facing components should be water-cooled in JT-60SA. A cassette module of divertor is introduced for remote maintenance. The divertor targets are mounted on the cassette. A brazed carbon fiber composite target is promising candidate for the divertor target. The latest results of mock-ups test clarified that thermal fatigue life cycles are more than 1000 cycles of 15 MW/m
10 sec. The divertor is designed to control divertor detachment for heat load reduction. The vertical targets and a "V-shaped corner" like as that in ITER are adopted to enhance detachment. Divertor heat load and pumping efficiency has been evaluated, using 2D plasma fluid (SOLDOR) and neutral Monte-Carlo (NEUT2D) code. The plasma detachment occurs near the outer-strike point within the "V-shaped corner", which results in low peak heat flux density 5.8 MW/m for the case with additional gas puff of 510
/s compared to 11.4 MW/m for the case without "V-shaped corner".
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
Kubo, Hirotaka; Sasaki, Akira; Moribayashi, Kengo; Higashijima, Satoru; Takenaga, Hidenobu; Shimizu, Katsuhiro; Nakano, Tomohide; Whiteford, A.*; Sugie, Tatsuo
Journal of Nuclear Materials, 363-365, p.1441 - 1445, 2007/06
Times Cited Count：6 Percentile：42.5(Materials Science, Multidisciplinary)no abstracts in English
Asakura, Nobuyuki; Kawashima, Hisato; Shimizu, Katsuhiro; Sakurai, Shinji; Fujita, Takaaki; Takenaga, Hidenobu; Nakano, Tomohide; Kubo, Hirotaka; Higashijima, Satoru; Hayashi, Takao; et al.
Europhysics Conference Abstracts (CD-ROM), 31F, 4 Pages, 2007/00
Divertor design for the JT-60 SA has been progressing in order to handle large heat flux during full pulse duration of 100 s. Divertor should be suitable for single null plasma experiments with the full power injection of 41 MW. The simulation results using 2D fluid (plasma) and Monte-Carlo (neutral) code are summarized. Lower single-null divertor is designed for ITER-like plasma configuration in order to study physics concept of the ITER divertor: control of the plasma detachment. Simulation results for various divertor geometries showed that the vertical target with V-shaped corner can produce plasma detachment near the outer strike-point for medium edge plasma density. It was also demonstrated that the divertor plasma became attached to move the outer strike point above the V-corner, suggesting that recover from sever detachment can be achieved by changing the plasma location. USN divertor will be designed for high-
plasma experiments with the highest shaping plasma of S=6.
Wang, F.*; Nakamura, Kazuo*; Mitarai, Osamu*; Kurihara, Kenichi; Kawamata, Yoichi; Sueoka, Michiharu; Sato, Konosuke*; Zushi, Hideki*; Hanada, Kazuaki*; Sakamoto, Mizuki*; et al.
Kyushu Daigaku Oyo Rikigaku Kenkyujo RIAM Foramu 2006 Koen Yoshi, p.138 - 141, 2006/06
no abstracts in English
Nakano, Tomohide; Asakura, Nobuyuki; Takenaga, Hidenobu; Kubo, Hirotaka; Miura, Yukitoshi; Shimizu, Katsuhiro; Konoshima, Shigeru; Masaki, Kei; Higashijima, Satoru; JT-60 Team
Nuclear Fusion, 46(5), p.626 - 634, 2006/05
Times Cited Count：21 Percentile：57.27(Physics, Fluids & Plasmas)In order to understand plasma-wall interactions in a long time scale, the discharge pulse length has been extended from 15 s to 65 s, with the NB-heating duration extended to 30 s. Nearly-saturation of the divertor plates was observed in the latter half of long pulse ELMy H-mode discharges. Particle sink into the divertor plates gradually decreased, and subsequently, wall-pumping efficiency became zero. This wall saturation resulted in a rise of the main plasma density without any auxiliary particle supply besides NB with divertor-pumping. Even when the total injected energy reached up to 350 MJ in a discharge, neither sudden increase of carbon generation such as carbon bloom nor increase of the dilution of the main plasma was observed.
Takenaga, Hidenobu; Asakura, Nobuyuki; Kubo, Hirotaka; Higashijima, Satoru; Konoshima, Shigeru; Nakano, Tomohide; Oyama, Naoyuki; Porter, G. D.*; Rognlien, T. D.*; Rensink, M. E.*; et al.
Nuclear Fusion, 45(12), p.1618 - 1627, 2005/12
Times Cited Count：18 Percentile：51.39(Physics, Fluids & Plasmas)no abstracts in English
Nakano, Tomohide; Koide, Yoshihiko; Honda, Atsushi; Umeda, Naotaka; Akino, Noboru; Higashijima, Satoru; Takenaga, Hidenobu; Kubo, Hirotaka
Purazuma, Kaku Yugo Gakkai-Shi, 81(9), p.708 - 716, 2005/09
no abstracts in English
Takenaga, Hidenobu; Asakura, Nobuyuki; Higashijima, Satoru; Nakano, Tomohide; Kubo, Hirotaka; Konoshima, Shigeru; Oyama, Naoyuki; Isayama, Akihiko; Ide, Shunsuke; Fujita, Takaaki; et al.
Journal of Nuclear Materials, 337-339, p.802 - 807, 2005/03
Times Cited Count：14 Percentile：67.84(Materials Science, Multidisciplinary)no abstracts in English
Takenaga, Hidenobu; Asakura, Nobuyuki; Kubo, Hirotaka; Higashijima, Satoru; Konoshima, Shigeru; Nakano, Tomohide; Oyama, Naoyuki; Porter, G. D.*; Rognlien, T. D.*; Rensink, M. E.*; et al.
Proceedings of 20th IAEA Fusion Energy Conference (FEC 2004) (CD-ROM), 8 Pages, 2004/11
no abstracts in English
Asakura, Nobuyuki; Kato, Takako*; Takamura, Shuichi*; Tanabe, Tetsuo*; Higashijima, Satoru; Iio, Shunji*; Ozeki, Takahisa; Ono, Yasushi*; Kawano, Yasunori; Nakajima, Noriyoshi*; et al.
Purazuma, Kaku Yugo Gakkai-Shi, 79(11), p.1194 - 1196, 2003/11
The ITPA (International Tokamak Physics Activity) meeting was held at Scientific Educational Center of Ioffe Institute (St. Petersburg) in Russia. In the meeting, topical physics group meetings of "Scrape-off-layer and Divertor Physics", "MHD, Disruptions and Control", "Energetic Particles, Heating and Steady State Operation", and "Diagnostics" were carried out. The joint meeting for plasma control was also held. In getting many participants from Japan, Europe, Russia, ITER international team, U.S.A. and China (observer), the active discussions were carried out. The outline of discussions in each topical group and in the plasma control joint meeting is reported here.
Takenaga, Hidenobu; Higashijima, Satoru; Oyama, Naoyuki; Bruskin, L. G.; Koide, Yoshihiko; Ide, Shunsuke; Shirai, Hiroshi; Sakamoto, Yoshiteru; Suzuki, Takahiro; Hill, K. W.*; et al.
Nuclear Fusion, 43(10), p.1235 - 1245, 2003/10
Times Cited Count：71 Percentile：88.64(Physics, Fluids & Plasmas)no abstracts in English
Konoshima, Shigeru; Tamai, Hiroshi; Miura, Yukitoshi; Higashijima, Satoru; Kubo, Hirotaka; Sakurai, Shinji; Shimizu, Katsuhiro; Takizuka, Tomonori; Koide, Yoshihiko; Hatae, Takaki; et al.
Journal of Nuclear Materials, 313-316(1-3), p.888 - 892, 2003/03
Times Cited Count：20 Percentile：77.2(Materials Science, Multidisciplinary)The emissivity distribution of the JT-60U divertor plasmas has been studied with the bolometer diagnostics. Line integrated bolometer signals of 48 chords have been successfully mapped onto the JT-60U W-shaped divertor geometry. 2D radiation profiles provide an intuitive understanding of the experiments and comparison of experiment with simulation for divertor characterization. An extended region of the radiation along both divertor legs was found in ELMing H-mode discharges with line-average density of 3.7x10
m
. A highly radiative zone with an emissivity of around 15 MWm at the inboard side and around 8 MWm at outboard side has been identified to extend more than 10 cm from each target plate toward the x-point. About 70 % of the input neutral beam power, 11 MW, is dissipated as a divertor radiation in that region.
Kubo, Hirotaka; Sakurai, Shinji; Higashijima, Satoru; Takenaga, Hidenobu; Itami, Kiyoshi; Konoshima, Shigeru; Nakano, Tomohide; Koide, Yoshihiko; Asakura, Nobuyuki; Shimizu, Katsuhiro; et al.
Journal of Nuclear Materials, 313-316(1-3), p.1197 - 1201, 2003/03
Times Cited Count：19 Percentile：75.79(Materials Science, Multidisciplinary)no abstracts in English
Sugie, Tatsuo; Hatae, Takaki; Koide, Yoshihiko; Fujita, Takaaki; Kusama, Yoshinori; Nishitani, Takeo; Isayama, Akihiko; Sato, Masayasu; Shinohara, Koji; Asakura, Nobuyuki; et al.
Fusion Science and Technology (JT-60 Special Issue), 42(2-3), p.482 - 511, 2002/09
Times Cited Count：6 Percentile：3.03(Nuclear Science & Technology)The diagnostic system of JT-60U (JT-60upgrade) is composed of about 50 individual diagnostic devices. Recently, the detailed radial profile measurements of plasma parameters have been improved, so that the internal structure of plasmas has been explored. The understanding of plasma confinement has been enhanced by density and temperature fluctuation measurements using a mm-wave reflectometer and electron cyclotron emission measurements respectively. In addition, the real-time control experiments of electron density, neutron yield, radiated power and electron temperature gradient have been carried out successfully by corresponding diagnostic devices. These measurements and the real time control contribute to improving plasma performance. Diagnostic devices for next generation fusion devices such as a CO2 laser interferometer/polarimeter and a CO2 laser collective Thomson scattering system have been developed.
