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Journal Articles

Welding technology on sector assembly of the JT-60SA vacuum vessel

Shibama, Yusuke; Okano, Fuminori; Yagyu, Junichi; Kaminaga, Atsushi; Miyo, Yasuhiko; Hayakawa, Atsuro*; Sagawa, Keiich*; Mochida, Tsutomu*; Morimoto, Tamotsu*; Hamada, Takashi*; et al.

Fusion Engineering and Design, 98-99, p.1614 - 1619, 2015/10

 Times Cited Count:3 Percentile:32.14(Nuclear Science & Technology)

The JT-60SA vacuum vessel (150 tons) is a double wall torus structure and the maximum major radius of 5.0 m and height of 6.6 m. The manufacturing design concept is that the vessel is split in the 10 toroidal sectors manufactured at factory, and assembled on-site; seven of the 40-degree sectors, two of the 30-degree beside final one, and the final of the 20-degree. The final sector is assembled with the VV thermal shield and toroidal field magnets into the 340-degree as prepared in one sector. Sectors are temporally fitted on-site and adjusted one over the other before the assembly. After measurement of the dimensions and the reference, these sectors are transferred onto the cryostat base. First, three 80-degree sectors are manufactured with mating each 40-degree sector by direct joint welding. The rest sectors including the final sector are jointed with splice plates. Welding manipulator and its guide rails are used for these welding. In this paper, the detail of the VV sectors assembly including the final sector is explained. Welding technologies to joint the two of 40-degree sectors are reported with the present manufacturing status and the welding trial on the vertical stub with the partial mock-up of the final sector are discussed with the assembly process.

Journal Articles

Mechanical properties on closure welding for JT-60SA cryostat

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.

JAEA Reports

Assembly work and transport of JT-60SA cryostat base

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


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.

Journal Articles

Assembly study for JT-60SA tokamak

Shibanuma, Kiyoshi; Arai, Takashi; Hasegawa, Koichi; Hoshi, Ryo; Kamiya, Koji; Kawashima, Hisato; Kubo, Hirotaka; Masaki, Kei; Saeki, Hisashi; Sakurai, Shinji; et al.

Fusion Engineering and Design, 88(6-8), p.705 - 710, 2013/10

 Times Cited Count:8 Percentile:59.34(Nuclear Science & Technology)

Journal Articles

Welding technology R&D on port joint of JT-60SA vacuum vessel

Shibama, Yusuke; Masaki, Kei; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira; Onawa, Toshio*; Araki, Takao*; Asano, Shiro*

Fusion Engineering and Design, 88(9-10), p.1916 - 1919, 2013/10

 Times Cited Count:2 Percentile:21.27(Nuclear Science & Technology)

This presentation focuses on the welding technology R&D between the JT-60SA vacuum vessel and the ports. The vacuum vessel is designed to allow port bore penetration to access the vessel inside for plasma diagnostics, and so on. There are various types of 73 ports and these are categorized by their locations; the upper/lower vertical, the upper/lower oblique, and the horizontal. Ports are onsite-welded onto the VV port stub after the assembly of the VV. This assembly sequence involves the out-vessel components such as VV thermal shield and toroidal field magnets, so that these ports welding are accessed from the inside of the vessel and limited by the internal port wall. The one of the most difficult ports are the upper vertical port with corner radius of 50 mm under narrow space, and it is necessary to clarify mobility of the weld torch head. The port weldability is discussed with the mock-up trial, which consists of the partial test pieces of the product size. The TIG welding manipulator, optimized for this R&D, is prepared by its operational simulation and examined not to interfere with the internal port wall.

Journal Articles

Manufacturing and development of JT-60SA vacuum vessel and divertor

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 200$$^{circ}$$C 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.

Journal Articles

Design study of top lid with clamp structure in JT-60SA cryostat

Nakamura, Shigetoshi; Shibama, Yusuke; Masaki, Kei; Sakasai, Akira

Plasma Science and Technology, 15(2), p.188 - 191, 2013/02

 Times Cited Count:0 Percentile:0.01(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$$^{-3}$$ 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.

Journal Articles

JT-60SA vacuum vessel manufacturing and assembly

Masaki, Kei; Shibama, Yusuke; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Fusion Engineering and Design, 87(5-6), p.742 - 746, 2012/08

 Times Cited Count:14 Percentile:76.37(Nuclear Science & Technology)

The JT-60SA vacuum vessel (VV) has a D-shaped poloidal cross section and a toroidal configuration with 10$$^{circ}$$ segmented facets. A double wall structure is adopted to ensure high rigidity at operational load and high toroidal one-turn resistance. The material is 316L stainless steel with low cobalt content ($$<$$ 0.05wt%). In the double wall, boric-acid water (max. 50$$^{circ}$$C) is circulated at plasma operation to reduce the nuclear heating of the superconducting magnets. For baking, nitrogen gas (200$$^{circ}$$C) is circulated in the double wall after draining of the boric-acid water. The manufacturing of the VV started in November 2009 after a fundamental welding R&D and a trial manufacturing of 20$$^{circ}$$ upper half mock-up. A basic VV assembly scenario and procedure were studied to complete the 360$$^{circ}$$ VV including positioning method and joint welding between sectors considering misalignment.

Journal Articles

Design and manufacturing of JT-60SA vacuum vessel

Masaki, Kei; Shibama, Yusuke; Sakurai, Shinji; Katayama, Masahiro*; Sakasai, Akira

Fusion Engineering and Design, 86(9-11), p.1872 - 1876, 2011/10

 Times Cited Count:5 Percentile:36.36(Nuclear Science & Technology)

JT-60SA vacuum vessel (VV) has the outer diameter of 10 m and the height of 6.6 m. The VV is supported by 9 legs. The material is 316L with low cobalt content of $$<$$0.05wt%. The VV has a double wall structure composed of inner/outer shells and ribs to ensure high rigidity at operational load and high toroidal one-turn resistance of $$sim$$16$$mu$$$$Omega$$ simultaneously. The double wall thicknesses are 194 mm at inboard and 242 mm at outboard. Inner/outer shells have 18-mm thicknesses. In the double wall, boric-acid water of $$sim$$50$$^{circ}$$C circulates at plasma operation to reduce nuclear heating of the superconducting coils. At the baking of 200$$^{circ}$$C, nitrogen gas circulates in the double wall. Fundamental welding R&D and a trial manufacturing of the 20$$^{circ}$$ upper half of the VV have been performed to study the manufacturing procedure. After the confirmation of the quality of the mock-up, manufacturing of the actual VV started in December 2009.

Journal Articles

Fundamental welding R&D results for manufacturing vacuum vessel of JT-60SA

Asano, Shiro*; Okuyama, Toshihisa*; Onawa, Toshio*; Yanagi, Yutaka*; Ejiri, Mitsuru*; Kanahara, Toshio*; Ichihashi, Koji*; Kikuchi, Atsushi*; Mizumaki, Shoichi*; Masaki, Kei; et al.

Fusion Engineering and Design, 86(9-11), p.1816 - 1820, 2011/10

 Times Cited Count:11 Percentile:69.09(Nuclear Science & Technology)

The real vacuum vessel (VV) manufacturing of JT-60SA has started since Nov. 2009 at Toshiba. Prior to starting manufacturing, fundamental welding R&Ds had been performed by three stages. In the first stage, primary tests for screening welding method were performed. In the second stage, the trial welding for 1m-long straight and curved double shell samples were conducted. The dependences of welding quality and distortion on the welding conditions, such as arc voltage and current, setting accuracy, welding sequence, the shape of grooves, etc. were measured. In addition, welding condition with low heat input was explored. In the last stage, fabrication sequence was confirmed and established by the trial manufacturing of the 20$$^{circ}$$ upper half mock-up. This poster presents the R&D results obtained in the first and second stages.

Journal Articles

Manufacturing status of JT-60SA vacuum vessel and the related technology of welding

Shibama, Yusuke; Masaki, Kei; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Proceedings of 2011 ASME Pressure Vessels and Piping Conference (PVP 2011) (CD-ROM), 10 Pages, 2011/07

This paper focuses on the JT-60SA vacuum vessel (VV, 150 tons) and presents manufacturing status of the VV with the design concept and the related technology of welding. The VV is a torus type vessel to ensure the sufficient ultrahigh vacuum space for core plasma and consists of 18 sectors with 73 port penetrations. The dimensions are the maximum major radius of 5.0 m and height of 6.6 m with a double wall structure to secure the stiffness against operational loads. The type 316L stainless steel is selected as a structural material and various welding technologies are developed. The weldment is mostly manipulated to achieve uniform welding quality and the welding conditions are evaluated to explore the distortion reduction, and to increase deposition rate. These resultants are applied to the 20 degree upper half mock-up and the manufacturing procedures, the correction of the welding distortion, and the optimization of constraint jigs are obtained.

Journal Articles

Design and trial manufacturing of JT-60SA vacuum vessel

Masaki, Kei; Shibama, Yusuke; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Nihon Genshiryoku Gakkai Wabun Rombunshi, 10(1), p.55 - 62, 2011/01

JT-60 is planned to be upgraded to JT-60SA superconducting tokamak machine. This project is the JA-EU satellite tokamak program under both Broader Approach program and Japanese domestic program. The JT-60SA tokamak is composed of the following main components; vacuum vessel (VV), thermal shield, superconducting coils (toroidal field coil, equilibrium field coil, center solenoid), cryostat, heating facilities. The VV has a D-shape poloidal cross section and a double wall structure to ensure high rigidity and high toroidal one-turn resistance simultaneously. The material of the VV is 316L stainless steel with low cobalt content of $$<$$ 0.05wt%. Before start of the VV manufacturing, fundamental welding R&D was performed to study the manufacturing procedures. The manufacturing procedures were successfully established with a trial manufacturing of 20 $$^{circ}$$ upper half of the VV. Based on the results, the actual VV manufacturing has started in November 2009.

Journal Articles

Design and fabrication status of JT-60SA vacuum vessel

Shibama, Yusuke; Masaki, Kei; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Nihon Kikai Gakkai M&M 2010 Zairyo Rikigaku Kanfarensu Koen Rombunshu (CD-ROM), p.239 - 241, 2010/10

Present JT-60U is upgraded to be a fully superconducting coil tokamak, and one of the main components dedicated by Japan is a vacuum vessel. This paper presents a design status of the vacuum vessel; the design concept and trial manufacture. The design concept is developed from the ASME Boiler and Pressure Vessel Code Section VIII Division 2, and the damage tolerant concept is adopted into the welding part hardly inspected. The typical size of the vessel segment is manufactured to validate the welding technologies, and to select the technical elements. Feasibility to manufacture the real structure is discussed with present perspectives.

JAEA Reports

Conceptual design of the SlimCS fusion DEMO reactor

Tobita, Kenji; Nishio, Satoshi*; Enoeda, Mikio; Nakamura, Hirofumi; Hayashi, Takumi; Asakura, Nobuyuki; Uto, Hiroyasu; Tanigawa, Hiroyasu; Nishitani, Takeo; Isono, Takaaki; et al.

JAEA-Research 2010-019, 194 Pages, 2010/08


This report describes the results of the conceptual design study of the SlimCS fusion DEMO reactor aiming at demonstrating fusion power production in a plant scale and allowing to assess the economic prospects of a fusion power plant. The design study has focused on a compact and low aspect ratio tokamak reactor concept with a reduced-sized central solenoid, which is novel compared with previous tokamak reactor concept such as SSTR (Steady State Tokamak Reactor). The reactor has the main parameters of a major radius of 5.5 m, aspect ratio of 2.6, elongation of 2.0, normalized beta of 4.3, fusion out put of 2.95 GW and average neutron wall load of 3 MW/m$$^{2}$$. This report covers various aspects of design study including systemic design, physics design, torus configuration, blanket, superconducting magnet, maintenance and building, which were carried out increase the engineering feasibility of the concept.

Journal Articles

Design of lower divertor for JT-60SA

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:9 Percentile:53(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.

Journal Articles

Design status of JT-60SA vacuum vessel

Shibama, Yusuke; Masaki, Kei; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Journal of Plasma and Fusion Research SERIES, Vol.9, p.180 - 185, 2010/08

JT-60SA is a combined JA-EU satellite tokamak program, aiming at the ITER program supports as well as the supplements toward the DEMO, under both broader approach agreement and the JA domestic program. The VV is a vessel to ensure sufficient ultrahigh vacuum space and one turn toroidal resistance for plasma breakdown. A double wall structure is selected to secure the higher rigidity against operational mechanical loads. The space between walls is utilized for the neutron shielding by 323 K boron water circulation, as well as for baking at 473 K by nitrogen gas flow to achieve the vacuum less than 10$$^{-5}$$ Pa. Present design status of the structural integrity is discussed with numerical analyses, which are issues of a seismic event and plasma disruptions. The feasibility of the VV manufacture is studied and latest status is presented.

Journal Articles

Basic concept of JT-60SA tokamak assembly

Shibanuma, Kiyoshi; Arai, Takashi; Kawashima, Hisato; Hoshino, Katsumichi; Hoshi, Ryo; Kobayashi, Kaoru; Sawai, Hiroaki; Masaki, Kei; Sakurai, Shinji; Shibama, Yusuke; et al.

Journal of Plasma and Fusion Research SERIES, Vol.9, p.276 - 281, 2010/08

The JT-60 SA project is a combined project of JA-EU satellite tokamak program under the Broader Approach (BA) agreement and JA domestic program. Major components of JT-60SA for assembly are vacuum vessel (VV), superconducting coils (TF coils, EF coils and CS coil), in-vessel components such as divertor, thermal shield and cryostat. An assembly frame (with the dedicated cranes), which is located around the tokamak, is adopted to carry out effectively the assembly of tokamak components in the tokamak hall, independently of the facility cranes in the building. The assembly frame also provides assembly tools and jigs with jacks to support temporarily the components as well as to adjust the components at right positions. In this paper, the assembly scenario and scequence of the major components such as VV and TFC and the concept of the assembly frame including special jigs and fixtures are discussed.

Journal Articles

Compact DEMO, SlimCS; Design progress and issues

Tobita, Kenji; Nishio, Satoshi; Enoeda, Mikio; Kawashima, Hisato; Kurita, Genichi; Tanigawa, Hiroyasu; Nakamura, Hirofumi; Honda, Mitsuru; Saito, Ai*; Sato, Satoshi; et al.

Nuclear Fusion, 49(7), p.075029_1 - 075029_10, 2009/07

 Times Cited Count:125 Percentile:98.18(Physics, Fluids & Plasmas)

Recent design study on SlimCS focused mainly on the torus configuration including blanket, divertor, materials and maintenance scheme. For vertical stability of elongated plasma and high beta access, a sector-wide conducting shell is arranged in between replaceable and permanent blanket. The reactor adopts pressurized-water-cooled solid breeding blanket. Compared with the previous advanced concept with supercritical water, the design options satisfying tritium self-sufficiency are relatively scarce. Considered divertor technology and materials, an allowable heat load to the divertor plate should be 8 MW/m$$^{2}$$ or lower, which can be a critical constraint for determining a handling power of DEMO (a combination of alpha heating power and external input power for current drive).

Journal Articles

Mock-up test results of monoblock-type CFC divertor armor for JT-60SA

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:8 Percentile:53.11(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$$^{2}$$ 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$$^{2}$$ as required. This summarizes the recent progress of design and mock-up test results for JT-60SA divertor armor.

Journal Articles

Design, R&D and assessment of performance of the JT-60SA upper divertor

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:10.95(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$$^{2}$$$$times$$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$$^{2}$$ for the case with additional gas puff of 5$$times$$10$$^{21}$$/s compared to 11.4 MW/m$$^{2}$$ for the case without "V-shaped corner".

62 (Records 1-20 displayed on this page)