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

https://doi.org/10.1016/j.fusengdes.2015.06.195

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.

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

https://doi.org/10.1016/j.fusengdes.2015.06.108

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

https://doi.org/10.1016/j.fusengdes.2015.06.018

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 200C (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 220C temperature region have been performed for the current coils design. Weight reduction of the seven candidate insulators was measured at different heating times under 180C, 200C and 220C 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.

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

https://doi.org/10.1016/j.fusengdes.2014.04.026

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.

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

https://doi.org/10.1585/pfr.8.1405153

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 for 5 s and 1 MW/m 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.

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

https://doi.org/10.1016/j.fusengdes.2013.01.100

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.

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

https://doi.org/10.1016/j.fusengdes.2012.02.014

The JT-60SA vacuum vessel (VV) has a D-shaped poloidal cross section and a toroidal configuration with 10 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. 50C) is circulated at plasma operation to reduce the nuclear heating of the superconducting magnets. For baking, nitrogen gas (200C) 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 upper half mock-up. A basic VV assembly scenario and procedure were studied to complete the 360 VV including positioning method and joint welding between sectors considering misalignment.

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

https://doi.org/10.1016/j.fusengdes.2011.02.008

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 16 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 50C circulates at plasma operation to reduce nuclear heating of the superconducting coils. At the baking of 200C, nitrogen gas circulates in the double wall. Fundamental welding R&D and a trial manufacturing of the 20 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.

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

https://doi.org/10.1016/j.jnucmat.2011.01.085

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.

Evaluation of heat and particle controllability on the JT-60SA divertor

Kawashima, Hisato; Hoshino, Kazuo; Shimizu, Katsuhiro; Takizuka, Tomonori; Ide, Shunsuke; Sakurai, Shinji; Asakura, Nobuyuki

Journal of Nuclear Materials, 415(Suppl.1), p.S948 - S951, 2011/08

https://doi.org/10.1016/j.jnucmat.2010.12.320

The divertor design of the JT-60SA tokamak device is finalized according to the engineering requirements and the physical analyses with the SONIC code simulations. Assuming the steady-state high beta core plasmas with 41 MW heating power, high heat and particle fluxes flowing out from core to SOL arrive at the divertor targets and give a large heat load. From the engineering viewpoint, the allowable heat load is restricted below 15 MW/m by the tolerability of the target material and structure. As a scenario to reduce the heat load, the vertical target configuration is adopted to receive the heat load on the wide area. In addition, the V-shaped corner is set to enhance the recycling at the outer side divertor where receives a relatively large heat load. Then, the remote radiative cooling is optimized by control of the D gas puffing, the impurity seeding and the divertor pumping.