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Tsuru, Daigo; Sakurai, Shinji; Nakamura, Shigetoshi; Ozaki, Hidetsugu; Seki, Yohji; Yokoyama, Kenji; Suzuki, Satoshi
Fusion Engineering and Design, 98-99, p.1403 - 1406, 2015/10
Times Cited Count：4 Percentile：30.44(Nuclear Science & Technology)Shibama, Yusuke; Nakamura, Shigetoshi; Masaki, Kei; Sakasai, Akira
Proceedings of 23rd International Conference on Nuclear Engineering (ICONE-23) (DVD-ROM), 5 Pages, 2015/05
The cryostat, made of type 304 stainless steel, is required to fulfil the structural integrity and the vacuum tightness at room temperature, and this paper focuses on the fillet welding mechanical properties as a vacuum seal, especially tensile behavior and fatigue strength. Although the lid at the top is a first major part to be removed when the devices inside would be stated in faulted conditions, the closure process is expected to be low cost and simple, and examined with structural clamping and fillet welding as a vacuum seal since the cryostat is not an usual pressure vessel. This standard strength is designed as a 12 mm leg length and reduction of the welding deposition is surveyed with the other comparative specimens of two leg lengths (6 mm, 9 mm). As a result, the region linearly responded to the loading of the 9 mm specimen sufficiently envelops the standard design strength, and then sufficient fatigue strength is confirmed with the linear response limit load as an amplitude until 2000 cycles. Application of the fillet welding to the closure welding is discussed in this paper.
Nakamura, Shigetoshi; Sakurai, Shinji; Ozaki, Hidetsugu; Seki, Yohji; Yokoyama, Kenji; Sakasai, Akira; Tsuru, Daigo
Fusion Engineering and Design, 89(7-8), p.1024 - 1028, 2014/10
Times Cited Count：5 Percentile：34.70(Nuclear Science & Technology)Carbon Fiber Composite mono-block divertor target is required for power handling in JT-60SA. Heat removal capability of the target is degraded by joint defect which is induced in manufacturing process. For screening heat removal capability, infrared thermography inspection (IR inspection) is improved an accuracy for the target using threaded cooling tube. In IR inspection, the targets heated at 95
C by hot water in steady state condition are instantaneously cooled down by cold water flow of 5C in three channels of test section. The heat removal capability of the targets is evaluated with comparing the transient thermal response time between defect-free and tested targets. A construction of a database for a correlation between the known defects, maximum surface temperatures in the heat load test and the IR inspection are successfully completed. Screening criteria is set with finite element methods based on the database.
Nishiyama, Tomokazu; Yagyu, Junichi; Nakamura, Shigetoshi; Masaki, Kei; Okano, Fuminori; Sakasai, Akira
Heisei-26-Nendo Hokkaido Daigaku Sogo Gijutsu Kenkyukai Hokokushu (DVD-ROM), 6 Pages, 2014/09
no abstracts in English
Yamada, Hirokazu*; Sakurai, Shinji; Nakamura, Shigetoshi
FAPIG, (187), p.28 - 31, 2014/02
The activity of "Broader approach (BA)" is carried out under the Japan-EU collaboration towards the early realization of nuclear fusion energy, and the construction of JT-60SA (Super Advanced) has been started as a part of BA. Divertor target of JT-60 consisted of carbon fiber composite tiles bolted on heat sink plate. Due to extension of plasma heating power and pulse duration, divertor target for JT-60SA has to be changed to the concept of carbon fiber block jointed to cooling tube of Cu-alloy for active cooling. Brazing joint between the carbon block and cooling tube is easy to cause joint defect due to the difference in the coefficient of linear expansion of a material. The joint defect reduces heat removal performance of the target. On the occasion of the apparatus manufacture concerned, the structural improvement realized those problems. This paper reports the contents of a structural improvement in the divertor target manufacturing for JT-60SA, etc.
Suzuki, Sadaaki; Yagyu, Junichi; Masaki, Kei; Nishiyama, Tomokazu; Nakamura, Shigetoshi; Saeki, Hisashi; Hoshi, Ryo; Sawai, Hiroaki; Hasegawa, Koichi; Arai, Takashi; et al.
NIFS-MEMO-67, p.266 - 271, 2014/02
no abstracts in English
Okano, Fuminori; Masaki, Kei; Yagyu, Junichi; Shibama, Yusuke; Sakasai, Akira; Miyo, Yasuhiko; Kaminaga, Atsushi; Nishiyama, Tomokazu; Suzuki, Sadaaki; Nakamura, Shigetoshi; et al.
JAEA-Technology 2013-032, 32 Pages, 2013/11
JAEA-Technology-2013-032.pdf:8.86MB
Japan Atomic Energy Agency started to construct a fully superconducting tokamak experiment device, JT-60SA, to support the ITER since January, 2013 at the Fusion Research and Development Directorate in Naka, Japan. The JT-60SA will be constructed with enhancing the previous JT-60 infrastructures, in the JT-60 torus hall, where the ex-JT-60 machine was disassembled. The JT-60SA Cryostat Base, for base of the entire tokamak structure, were assembly as first step of this construction. The Cryostat Base (CB, 250 tons) is consists of 7 main made of stainless steel, 12m diameter and 3m height. It was built in the Spain and transported to the Naka site with the seven major parts split, via Hitachi port. The assembly work of these steps, preliminary measurements, sole plate adjustments of its height and flatness, and assembly of the CB. Introduces the concrete result of assembly work and transport of JT-60SA cryostat base.
Sakasai, Akira; Masaki, Kei; Shibama, Yusuke; Sakurai, Shinji; Hayashi, Takao; Nakamura, Shigetoshi; Ozaki, Hidetsugu; Yokoyama, Kenji; Seki, Yohji; Shibanuma, Kiyoshi; et al.
Proceedings of 24th IAEA Fusion Energy Conference (FEC 2012) (CD-ROM), 8 Pages, 2013/03
The JT-60SA vacuum vessel (VV) and divertor are key components for the performance requirements. Therefore the manufacturing and development of VV and divertor are in progress, inclusive of the superconducting magnets. The vacuum vessel has a double wall structure in high rigidity to withstand electromagnetic force at disruption and to keep high toroidal one-turn resistance. In addition, the double wall structure fulfills originally two functions. (1) The remarkable reduction of the nuclear heating in the superconducting magnets is made by boric-acid water circulated in the double wall. (2) The effective baking is enabled by nitrogen gas flow of 200C in the double wall after draining of water. Three welding types were chosen for the manufacturing of the double wall structure VV to minimize deformation by welding. Divertor cassettes with fully water cooled plasma facing components were designed to realize the JT-60SA lower single null closed divertor. The divertor cassettes in the radio-active VV have been developed to ensure compatibility with remote handling (RH) maintenance in order to allow long pulse high performance discharges with high neutron yield. The manufacturing of divertor cassettes with typical accuracy of *1 mm has been successfully completed. Brazed CFC (carbon fiber composite) monoblock targets for a divertor target have been manufactured by precise control of tolerances inside CFC blocks. The infrared thermography test of monoblock targets has been developed as new acceptance inspection.
Nakamura, Shigetoshi; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira
Plasma Science and Technology, 15(2), p.188 - 191, 2013/02
Times Cited Count：1 Percentile：4.17(Physics, Fluids & Plasmas)The JT-60SA project is to contribute to realization of fusion energy by supporting exploitation of ITER and by complementing ITER and engineering issues for DEMO reactors. A main component providing vacuum insulation, radiation shield, and tokamak machine components' support, is cryostat. We present integrity of top lid of the cryostat, which is final part to close a cryostat vessel. We calculate clamp structural parameters, which are weight, dimension, and stiffness, required to fasten a top flange of the top lid with a body flange of the cryostat vessel. To achieve vacuum insulation of 10
Pa, the top flange and the body flange are lightly welded. Under vacuum condition, tensile load is loaded to the weld by bending deformation of the top flange. Bending moment is loaded to the weld by radial component of the deformation. The weld needs clamp structure to reduce these loads. We present integrity of the top lid with clamp.
Shiraiwa, Shunichi*; Ide, Shunsuke; Ito, Satoshi*; Mitarai, Osamu*; Naito, Osamu; Ozeki, Takahisa; Sakamoto, Yoshiteru; Suzuki, Takahiro; Takase, Yuichi*; Tanaka, Shigetoshi*; et al.
Physical Review Letters, 92(3), p.035001_1 - 035001_4, 2004/01
Times Cited Count：51 Percentile：84.03(Physics, Multidisciplinary)no abstracts in English
Nakamura, Shigetoshi; Sakurai, Shinji; Ozaki, Hidetsugu; Sakasai, Akira; Seki, Yohji; Yokoyama, Kenji
no journal, ,
CFC (Carbon fiber Composite) Mono-block divertor target is required for power handling of 15 MW/m
in JT-60SA. Inspection method for screening heat removal capability of mono-block divertor target with infrared thermography is presented. The inspection detects a delay in the surface temperature evolution through an abrupt variation of the water temperature flowing in the cooling tube. Heat removal capability of the mono-block divertor target is evaluated with the delay. Results of heat load test and thermography inspection are considered to assess adequacy for the screening of the thermography inspection with finite element method. Dispersion in density and thermal conductivity of CFC block, coefficient of heat transfer of cooling water in screw-tube, emissivity of CFC, atmospheric temperature, corrected value of infrared thermography camera, and temperature of hot water and cool water cause error in the inspection. The effects of these factors are evaluated.
Yagyu, Junichi; Masaki, Kei; Suzuki, Sadaaki; Nishiyama, Tomokazu; Nakamura, Shigetoshi; Saeki, Hisashi; Hoshi, Ryo; Sawai, Hiroaki; Hasegawa, Koichi; Arai, Takashi; et al.
no journal, ,
no abstracts in English
Shibama, Yusuke; Masaki, Kei; Nakamura, Shigetoshi; Kaminaga, Atsushi; Miyo, Yasuhiko; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira
no journal, ,
JT-60SA is a fully superconducting coil tokamak upgraded from the JT-60U. This paper focuses on the vacuum vessel (VV, 150 tons) and cryostat (610 tons), whose structural concepts are developed from the ASME BPVC Section VIII Division 2. The VV is a stainless steel torus double-walled, which achieves high electrical resistivity in the toroidal and high stiffness in the light structure. The cryostat is large size vacuum thermal insulation vessel. The present status of both vessels is reported.
Takechi, Manabu; Sakurai, Shinji; Nakamura, Shigetoshi; Seki, Yohji; Ozaki, Hidetsugu; Yokoyama, Kenji
no journal, ,
no abstracts in English
Nakamura, Shigetoshi; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira
no journal, ,
no abstracts in English
Okano, Fuminori; Masaki, Kei; Shibama, Yusuke; Yagyu, Junichi; Nishiyama, Tomokazu; Miyo, Yasuhiko; Kaminaga, Atsushi; Suzuki, Sadaaki; Nakamura, Shigetoshi; Sakasai, Akira; et al.
no journal, ,
no abstracts in English
Nakamura, Shigetoshi; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira
no journal, ,
no abstracts in English
Tsuru, Daigo; Sakurai, Shinji; Nakamura, Shigetoshi; Ozaki, Hidetsugu; Seki, Yohji; Yokoyama, Kenji; Suzuki, Satoshi
no journal, ,
no abstracts in English
Nakamura, Shigetoshi; Sakurai, Shinji; Ozaki, Hidetsugu; Sakasai, Akira; Seki, Yohji; Yokoyama, Kenji
no journal, ,
no abstracts in English
Nakamura, Shigetoshi; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira
no journal, ,
The JT-60SA project is to contribute to realization of fusion energy by supporting exploitation of ITER and by complementing ITER and engineering issues for DEMO reactors. A main component, providing vacuum insulation, radiation shield, and components' support, is cryostat. Cryostat split in two major segments; base and vessel. The base is under the manufacturing, and the vessel is still in designing. We present design status of entire cryostat and structural analysis of the top lid, which is final part to close the cryostat vessel. To achieve vacuum insulation of 10Pa each mechanical joints' flanges of cryostat segments are lightly welded as vacuum sealing. The normal load conditions consist of; atmospheric pressure, heat load and electromagnetic force. The top lid of the cryostat is also required of the sufficient integrity and the certain stiffness to protect the sealing weldment. We present the structural integrity clarified by stress evaluation and adequate reinforcements.
