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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：3 Percentile：25.85(Nuclear Science & Technology)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：36.96(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.
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.
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.
Sakurai, Shinji; Higashijima, Satoru; Shibama, Yusuke; Hayashi, Takao; Ozaki, Hidetsugu; Masaki, Kei; Masuo, Hiroshige*; Shibanuma, Kiyoshi; Sakasai, Akira; JT-60SA Team
no journal, ,
Heat removal for heat flux of 15MW/m
and compatibility with remote handling maintenance are required for the lower divertor in JT-60SA. Vertical divertor targets and a private dome with V-shaped corner similar to ITER are applied to reduce heat flux by radiation enhancement. The lower divertor consists from 36 divertor cassettes with toroidal width of 10 degree for transporting through large horizontal port of vacuum vessel (VV). Each cassette is fixed on the three supports at bottom of VV. The cassette has coolant pipe connections to the coolant pipe headers in VV. The pipe connection can be cut and welded by remote handling tools. Although bolted CFC tiles on water cooled copper alloy heatsinks will be adopted for most part of divertor targets in the initial operation phase, brazed CFC monoblock targets will be applied partially. The bolted CFC targets will be replaced to CFC monoblock targets in accordance with increment of plasma heating power.
Sakurai, Shinji; Higashijima, Satoru; Kawashima, Hisato; Shibama, Yusuke; Hayashi, Takao; Ozaki, Hidetsugu; Shimizu, Katsuhiro; Masaki, Kei; Hoshino, Katsumichi; Ide, Shunsuke; et al.
no journal, ,
Lower single null closed divertor with vertical target will be installed at the start of the experiment phase for JT-60 Super Advanced (JT-60SA). Reproducibility of brazed CFC (carbon fiber composite) monoblock targets for a divertor target has been significantly improved by precise control of tolerances and metallization inside CFC blocks. Divertor cassette with fully water cooled plasma facing components and remote handling (RH) system shall be employed to allow long pulse high performance discharges with large neutron yield and they are designed compatible with limited position and size of maintenance ports. Static structural analysis for dead weight, coolant pressure and electromagnetic forces shows that displacement and stress in the divertor module are generally small.
Takechi, Manabu; Sakurai, Shinji; Nakamura, Shigetoshi; Seki, Yohji; Ozaki, Hidetsugu; Yokoyama, Kenji
no journal, ,
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.
Nakamura, Shigetoshi; Sakurai, Shinji; Ozaki, Hidetsugu; Sakasai, Akira; Seki, Yohji; Yokoyama, Kenji
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
