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JAEA Reports

Three-dimensional stress analysis of reflooding tunnel during submerging process using crack tensor model at Mizunami Underground Research Laboratory

Ozaki, Yusuke; Matsui, Hiroya; Kuwabara, Kazumichi; Tada, Hiroyuki*; Sakurai, Hideyuki*; Kumasaka, Hiroo*; Goke, Mitsuo*; Kobayashi, Shinji*

JAEA-Research 2016-007, 125 Pages, 2016/06


In Mizunami Underground Research Laboratory (MIU), the stress analysis of fractured rock have been performed with crack tensor model. In MIU, a reflooding test is performed at 500m stage. In this study, stress analysis of rock during submerging process of the tunnel is performed by using crack tensor model. The deformation of the rock under different water levels in the tunnel is simulated. The stress condition by high pressure due to inflow of groundwater into tunnel is also estimated. These simulation are performed under assumption that groundwater does not permeate into rock for the estimation of maximum pressure acting on the rock. The stress analysis with consideration of permeation of groundwater into rock is also conducted for the estimation of stress condition after the diffusion of water pressure in tunnel. The results of these analyses lead the conclusion that the pressure of the rock reaches the groundwater pressure near the face of tunnel when the tunnel is submerged.

Journal Articles

Development of remote pipe welding tool for divertor cassettes in JT-60SA

Hayashi, Takao; Sakurai, Shinji; Sakasai, Akira; Shibanuma, Kiyoshi; Kono, Wataru*; Onawa, Toshio*; Matsukage, Takeshi*

Fusion Engineering and Design, 101, p.180 - 185, 2015/12

 Times Cited Count:3 Percentile:28.28(Nuclear Science & Technology)

Remote pipe welding tool accessing from inside pipe has been newly developed for JT-60SA. Remote handling (RH) system is necessary for the maintenance and repair of in-vessel components such as lower divertor cassettes in JT-60SA. Cooling pipes, which connects between the divertor cassette and the vacuum vessel with bellows are required to be cut and welded in the vacuum vessel by RH system. The available space for RH system is very limited inside the vacuum vessel, especially around the divertor cassettes. Thus, the cooling pipes are required to be cut and weld from the inside in the vacuum vessel. The inner diameter, thickness and material of the cooling pipe are 54.2 mm, 2.8 mm and SUS316L, respectively. An upper pipe connected to the divertor cassette has a jut on the edge to fill the gap between pipes. Owing to the jut and two-times welding, the welding tool achieved the maximum allowable gap of 0.7 mm.

Journal Articles

Development of residual thermal stress-relieving structure of CFC monoblock target for JT-60SA divertor

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:3 Percentile:28.28(Nuclear Science & Technology)

Journal Articles

Development of magnetic sensors for JT-60SA

Takechi, Manabu; Matsunaga, Go; Sakurai, Shinji; Sasajima, Tadayuki; Yagyu, Junichi; Hoshi, Ryo*; Kawamata, Yoichi; Kurihara, Kenichi; JT-60SA Team; Nishikawa, T.*; et al.

Fusion Engineering and Design, 96-97, p.985 - 988, 2015/10

 Times Cited Count:9 Percentile:59.96(Nuclear Science & Technology)

Journal Articles

In-vessel coils for magnetic error field correction in JT-60SA

Matsunaga, Go; Takechi, Manabu; Sakurai, Shinji; Suzuki, Yasuhiro*; Ide, Shunsuke; Urano, Hajime

Fusion Engineering and Design, 98-99, p.1113 - 1117, 2015/10

 Times Cited Count:13 Percentile:76.47(Nuclear Science & Technology)

Journal Articles

Estimation of the lifetime of resin insulators against baking temperature for JT-60SA in-vessel coils

Sukegawa, Atsuhiko; Murakami, Haruyuki; Matsunaga, Go; Sakurai, Shinji; Takechi, Manabu; Yoshida, Kiyoshi; Ikeda, Yoshitaka

Fusion Engineering and Design, 98-99, p.2076 - 2079, 2015/10

 Times Cited Count:1 Percentile:10.43(Nuclear Science & Technology)

The JT-60SA project is a EU - JA satellite tokamak under Broader Approach in support of the ITER project. In-vessel coils are designed and assembled by JA. The resin-insulator is required to have a heat resistance against the baking temperature of vacuum vessel of $$sim$$200$$^{circ}$$C (40000 hour). Thus the assessment of the heat load is fundamental for the design of the coils. However, the estimation of the lifetime of resin-insulator under the high-temperature region has not been examined. In the present study, the estimation of the lifetime of seven candidate resin-insulators such as epoxy resin and cyanate-ester resin under the $$sim$$220$$^{circ}$$C temperature region have been performed for the current coils design. Weight reduction of the seven candidate insulators was measured at different heating times under 180$$^{circ}$$C, 200$$^{circ}$$C and 220$$^{circ}$$C environment using three thermostatic ovens, respectively. The reduction of the insulators has been used as input for Weibull-analysis towards Arrhenius-plot. Lifetime of the resins has been estimated for the first time at the high temperature region by the plot. Lifetime of the resin-insulators have been evaluated and discussed as well as the available temperature of the in-vessel coils.

Journal Articles

Infrared thermography inspection for monoblock divertor target in JT-60SA

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:4 Percentile:25.77(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$$^{circ}$$C by hot water in steady state condition are instantaneously cooled down by cold water flow of 5$$^{circ}$$C 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.

Journal Articles

Development of remote pipe cutting tool for divertor cassettes in JT-60SA

Hayashi, Takao; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Fusion Engineering and Design, 89(9-10), p.2299 - 2303, 2014/10

 Times Cited Count:9 Percentile:60.54(Nuclear Science & Technology)

Remote handling (RH) system is necessary for the maintenance and repair of in-vessel components of JT-60SA. Design study of RH system, focusing on the deployment of remote pipe cutting tool for JT-60SA divertor cassette is reported in this conference. Some cooling pipes on the outboard side in the divertor cassette should be cut and welded in the vacuum vessel. The outer diameter, thickness and material of the cooling pipe is 59.7 mm, 2.7 mm and SUS316L, respectively. Cutting tool head equips a disk cutter blade and rollers which are subjected to the reaction force. The cooling pipe is cut by rotating the cutting tool head with pushing out the disk cutter blade. Newly developed cutting tool indicates that the cooling pipe is cut by pushing out the disk cutter blade up to 30.5 mm in radius, i.e. 61 mm in diameter.

Journal Articles

Manufacturing of divertor target for JT-60SA

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.

Journal Articles

Development of Langmuir probes on divertor cassettes in JT-60SA

Fukumoto, Masakatsu; Sakurai, Shinji; Asakura, Nobuyuki; Itami, Kiyoshi

Plasma and Fusion Research (Internet), 8, p.1405153_1 - 1405153_10, 2013/11

Langmuir probes installed in the lower divertor region under high heat flux have been developed and manufactured for JT-60SA. A probe electrode with a head having a rooftop shape is made of a carbon fiber composite and can withstand heat fluxes of up to 10 MW/m$$^2$$ for 5 s and 1 MW/m$$^2$$ for 100 s. This has been achieved by increasing the volume of the probe electrode that is not directly exposed to the plasma. To minimize the reduction of the heat removal performance of the divertor, the Langmuir probes are installed in toroidal gaps with widths of 10mm between the divertor cassettes, without embedding them in the divertor tiles. Aluminum oxide coatings have been applied to insulate the probe electrodes from the divertor cassettes and to limit the toroidal thickness to 8 mm. Brazing of the nickel connectors to the probe electrodes has reduced the toroidal thickness of the Langmuir probes. A minimum spatial resolution of 13.5mm has been achieved to the Langmuir probes installed on the inner and outer divertor targets.

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:10 Percentile:63.62(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:19.77(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

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:19 Percentile:81.56(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

Present status of hydrogen production and the ammonia production by the thermochemical cycle; Introduction of IS cycle and ISN cycle

Kameyama, Hideo*; Sakurai, Makoto*; Masuda, Akiyuki*; Fukui, Tomoaki*; Onuki, Kaoru; Kubo, Shinji; Imai, Yoshiyuki

Suiso Enerugi Shisutemu, 37(1), p.3 - 10, 2012/03

The technical present status of hydrogen production process using IS thermochemical cycle was introduced. This process is experimentally investigated in Japan, U.S.A., Germany, France, Italy, India, China and Korea. Japan Atomic Energy Agency succeeded in consecutive hydrogen production as a proof examination. The trend of the research and development about the reactions, separation technology, device materials and the process equipment were reported. Thermochemical ammonia production cycle was also introduced. This new cycle is named ISN cycle which was modified from IS cycle in order to produce ammonia from water and nitrogen.

Journal Articles

Design and test of JT-60SA gas injection system

Miyo, Yasuhiko; Nakano, Tomohide; Sakurai, Shinji; Sakasai, Akira

Dai-18-Kai Bunshi Kagaku Kenkyusho Gijutsu Kenkyukai Hokokushu (CD-ROM), 5 Pages, 2012/00

no abstracts in English

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:7 Percentile:50.8(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

Flexible heat resistant neutron shielding resin

Sukegawa, Atsuhiko; Anayama, Yoshimasa*; Okuno, Koichi*; Sakurai, Shinji; Kaminaga, Atsushi

Journal of Nuclear Materials, 417(1-3), p.850 - 853, 2011/10

 Times Cited Count:20 Percentile:83.12(Materials Science, Multidisciplinary)

A flexible heat resistant neutron shielding material has been developed, which consists of polymer resin with 1 weight % boron. The neutron shielding performance of the developed resin, examined by the $$^{252}$$Cf neutron source is almost the same as that of the polyethylene. The outgas of H$$_{2}$$, H$$_{2}$$O, CO and CO$$_{2}$$ from the resin have been measured at 250 $$^{circ}$$C environment. The resin will be applied around the port of the vacuum vessel as an additional shielding material and prevented the effects on the neutron streaming of the superconducting tokamak device such as JT-60SA.

Journal Articles

Heat treatment for CuCrZr cooling tubes for JT-60SA monoblock-type divertor targets

Higashijima, Satoru; Sakurai, Shinji; Sakasai, Akira

Journal of Nuclear Materials, 417(1-3), p.912 - 915, 2011/10

 Times Cited Count:8 Percentile:55.43(Materials Science, Multidisciplinary)

JT-60SA divertor has to receive the maximum heat flux of $$sim$$15 MW/m$$^{2}$$ 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 $$sim$$0.65 $$^{circ}$$C/s and $$sim$$1.5 $$^{circ}$$C/s around 800 $$^{circ}$$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$$^{2}$$ as required without the CFC cracking.

Journal Articles

Design study of remote handling system for lower divertor cassettes in JT-60SA

Hayashi, Takao; Sakurai, Shinji; Shibanuma, Kiyoshi; Sakasai, Akira

Fusion Science and Technology, 60(2), p.549 - 553, 2011/08

 Times Cited Count:5 Percentile:40.36(Nuclear Science & Technology)

Design study of RH system, especially the expansion of the RH rail and replacement of the lower divertor cassettes, was described in this paper. The dimensions and weight of the divertor cassette, which is 10 degrees wide in toroidal direction, are 1.62$$^{L}$$ $$times$$ 0.57$$^{W}$$ $$times$$ 1.25$$^{H}$$ m and 800 kg, respectively. The RH system can use four horizontal ports whose inside dimensions are 0.66$$^{W}$$ $$times$$ 1.83$$^{H}$$ m. The space for RH system is very limited. The RH rail is installed before transporting divertor cassettes. The RH rail can cover 180 degrees in toroidal direction. A divertor cassette can be replaced by heavy weight manipulator (HWM) consists of an end effector, a telescopic arm and a vehicle. The HWM brings the divertor cassette to the front of another horizontal port, which is used for supporting the rail and/or carrying in and out equipments. Then another RH device, which is installed from outside the vacuum vessel, receives and brings out the divertor cassette.

213 (Records 1-20 displayed on this page)