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Journal Articles

Mechanical properties of full austenitic welding joint at cryogenic temperature for the ITER toroidal field coil structure

Iguchi, Masahide; Saito, Toru; Kawano, Katsumi; Chida, Yutaka; Nakajima, Hideo; Ogawa, Tsuyoshi*; Katayama, Yoshinori*; Ogata, Hiroshige*; Minemura, Toshiyuki*; Tokai, Daisuke*; et al.

Fusion Engineering and Design, 88(9-10), p.2520 - 2524, 2013/10

 Times Cited Count:8 Percentile:57.25(Nuclear Science & Technology)

ITER TFC structures are large welding structures made of heavy thick stainless steels. JAEA plans to apply narrow gap TIG welding with FMYJJ1 which is full austenitic stainless filler material to manufacture TFC structure. FMYJJ1 is specified in "Codes for Fusion Facilities -Rules on Superconducting Magnet Structure (2008)". In order to evaluate effect of base material combinations and thickness of welded joint on tensile properties at 4 K, tensile tests were conducted at 4 K by using tensile specimens taken from 40 mm thickness weld joints of four combinations and 200 mm thickness ones of two combinations of base materials. These weld joints were manufactured by one side narrow gap TIG welding with FMYJJ1. As the results, it was confirmed that yield and tensile strengths of welded joint at 4K were decreased with decreasing of nitrogen of base material, and there were no large distribution of strengths at 4 K along the thickness of welded joints of 200 mm thickness.

Journal Articles

Current status of the engineering design of the test modules for the IFMIF

Yamamoto, Michiyoshi; Arbeiter, F.*; Yokomine, Takehiko*; Wakai, Eiichi; Theile, J.*; Garcia, A. S.*; Rapisarda, D. S.*; Casal, N. I.*; Mas, A. S.*; Gouat, P.*; et al.

Fusion Engineering and Design, 88(6-8), p.746 - 750, 2013/10

 Times Cited Count:12 Percentile:71.3(Nuclear Science & Technology)

Under Broader Approach (BA) Agreement between EURATOM and Japan, IFMIF/EVEDA (International Fusion Materials Irradiation Facility/Engineering Validation and Engineering Design Activities) has been performed since the middle of 2007. The present EVEDA phase aims at producing a detailed, compete and fully integrated engineering design of IFMIF. The deivery of the Intermediate IFMIF engineering design report is foreseen mid-2013. The main function of the IFMIF is to provide the materials database for the design and licensing of DEMO reactor and further fusion rectors from the material sets irradiated in High Flux Test Modules (HFTM, Startup Monitoring Module), Medium Flux Test Modules (Creep Fatigues Test Module, Tritium Release Test Module, Liquid Breeder Validation Module) and Low Flux Test Modules of IFMIF. This paper is summarizing the current progress of the engineering design of the test modules within the IFMIF/EVEDA project.

Journal Articles

Novel granulation process of beryllide as advanced neutron multipliers

Nakamichi, Masaru; Kim, Jae-Hwan; Yonehara, Kazuo

Fusion Engineering and Design, 88(6-8), p.611 - 615, 2013/10

 Times Cited Count:33 Percentile:94(Nuclear Science & Technology)

Advanced neutron multipliers with lower swelling and higher stability at high temperature are desired in pebble-bed blankets, which would have a big impact on the design of a DEMO reactor, especially on the blanket operating temperature. Development of advanced neutron multipliers has been started by Japan and EU in the DEMO R&D as a part of the Broader Approach (BA) activities. Beryllium intermetallic compounds (beryllides) such as Be$$_{12}$$Ti are one of the most promising advanced neutron multipliers. In order to fabricate the beryllide pebbles, beryllide with shapes of block and/or rod is necessary when a melting granulation process is applied such as a rotating electrode method. However, beryllide is too brittle for the fabrication of blocks or rods by these methods. A plasma sintering method has been proposed as new technique which uses a non conventional consolidation process, because this method is simple, and is easy to control. It was clarified that the beryllide could be simultaneously synthesized and jointed by the plasma sintering method in the insert material region between two beryllide blocks, with no variation of the phase and hardness. Beryllide rod of Be$$_{12}$$Ti with 10 mm in diameter and 60 mm in length has been successfully fabricated by the plasma sintering method. Using this plasma-sintered beryllide rod, prototype pebble of beryllide was performed by a rotating electrode method. The prototype pebbles of Be$$_{12}$$Ti with 1 mm in average diameter were successfully fabricated. The present paper describes novel granulation process of beryllide using these methods including fabrication and granulation techniques.

Journal Articles

Demonstration on endurance of ion exchange membrane immersed in high-concentration tritiated water under the Broader Approach activities

Iwai, Yasunori; Sato, Katsumi; Kawamura, Yoshinori; Yamanishi, Toshihiko

Fusion Engineering and Design, 88(9-10), p.2319 - 2322, 2013/10

 Times Cited Count:4 Percentile:35.17(Nuclear Science & Technology)

The Nafion ion exchange membrane is a key material for electrolysis cells of the water detritiation system. Endurance of ion exchange membrane immersed into high-concentration tritiated water has been demonstrated under the Broader Approach activities, as a R&D on endurance of fuel cycle components at high tritium exposure. Long-term exposure of Nafion ion exchange membrane into 1.38 TBq/kg of tritiated water was conducted at room temperature for up to 2 years. The curves of percent elongation at break vs. dose and tensile strength vs. dose for the Nafion membranes immersed into tritiated water were well consistent with those for Nafion membranes irradiated to an equivalent dose with $$gamma$$ rays and electron beams. The results of ferric Fenton test indicated that the degradation directly by radiation was dominant at room temperature compared with that by reactions with radicals produced from water radiolysis. The curve of ion exchange capacity vs. dose for the Nafion membranes immersed into tritiated water was also well consistent with that for Nafion membranes irradiated to an equivalent dose with $$gamma$$ rays and electron beams. These results showed that the irradiation tests with $$gamma$$ rays and electron beams were effective to predict a degradation behavior of ion exchange membrane immersed into high-concentration tritiated water.

Journal Articles

Feeder components and instrumentation for the JT-60SA magnet system

Yoshida, Kiyoshi; Kizu, Kaname; Murakami, Haruyuki; Kamiya, Koji; Honda, Atsushi; Onishi, Yoshihiro; Furukawa, Masato; Asakawa, Shuji; Kuramochi, Masaya; Kurihara, Kenichi

Fusion Engineering and Design, 88(9-10), p.1499 - 1504, 2013/10

 Times Cited Count:6 Percentile:47.59(Nuclear Science & Technology)

The modifying of the JT-60U magnet system to the superconducting coils (JT-60SA) is progressing as a satellite facility for ITER by both parties of Japanese government and European commission (EU) in the Broader Approach agreement. The magnet system for JT-60SA consists of 18 Toroidal Field (TF) coils, a Central Solenoid (CS) with 4 modules, and 6 Equilibrium Field (EF) coils. The manufacturing of the JT-60SA magnet system is in progress in EU and Japan. The JT-60SA superconducting magnet system generates an average heat load of 3.2 kW at 4 K to the cryoplant, from nuclear and thermal radiation, conduction and electromagnetic heating, and requires current supplies 20 kA for 4 CS modules and 6 EF coils, 25.7 kA to 18 TF coils. The helium flow to remove this heat, consisting of supercritical helium at pressures up to 0.5 MPa and temperature between 4.4-4.8 K, is distributed to the coils and structures through the valve box (VB) from the cryoline connecting to the auxiliary cold box located outside the torus hall. The feeders also contain the electrical supplies from the current lead transitions to room temperature to the coil. The feeder components consist of the in-cryostat feeders with flexible parts to allow coil operational displacements from the connection pipes out of the cryostat, including S-bend conductor to allow differential thermal contraction and the coil terminal boxes (CTBs) with HIS current leads. A measurement and control system is required to monitor and control these coils and feeders for safety and optimal operational availability. For each coil, both current and supercritical helium are supplied from external systems and are controlled from a central system as part of the regular operation with plasma pulses. Quench detection instruments for superconducting coils, feeders and HTS current leads are provided as a separate, stand alone system.

Journal Articles

Fabrication and installation of equilibrium field coils for the JT-60SA

Tsuchiya, Katsuhiko; Kizu, Kaname; Murakami, Haruyuki; Kashiwa, Yoshitoshi; Yoshizawa, Norio; Yoshida, Kiyoshi; Hasegawa, Mitsuru*; Kuno, Kazuo*; Nomoto, Kazuhiro*; Horii, Hiroyuki*

Fusion Engineering and Design, 88(6-8), p.551 - 554, 2013/10

 Times Cited Count:8 Percentile:57.25(Nuclear Science & Technology)

The programme of constructing JT-60SA device is progressing under the framework of the Broader Approach project. Superconducting poloidal field (PF) coil system, which was decided to be procured by Japan, consists of a central solenoid (CS) with four solenoid modules and six equilibrium field (EF) coils. Each of EF coil has individual diameters, 4.5 to 12 m. Fabrication of EF4 coil, which is set at the lowermost of torus, was started from the beginning of 2009 as a first EF coil. EF4 coil has ten double pancake (DP) coils, and sizes of circularity were measured for all DP coil after curing process. Maximum error of circularity was 3.1 mm, which was nearly a half of the design tolerance, 6 mm. After stacking these DP coils, winding pack of EF4 was completed in the spring of 2012. After optimizing the positions of DP coils to cancel the error of circulation which each DP coil has, error of radial current centre of DP coils will be achieved in the range between + 0.2 to - 0.4 mm. Structural analysis of terminal structure was also performed. Terminal part has a pair of conductors bended toward the lower side of winding pack. A side of them (positive terminal) was covered by stainless steel armor to prevent the movement by electromagnetic force because a length of conductor was longer due to starting from the top of winding pack. Another side (negative terminal) was not covered by armor in the first design because this length was relatively short. However, it was clear on the structural analysis that mechanical strength of insulation around this terminal was not sufficient. Therefore, we also reinforced this side with stainless steel. From this April, fabrication of EF coils with large bore (larger than 8 m of diameter) will be started at the facility built in JAEA Naka site. In this paper, we will discuss about technological problem during the fabrication of large bore EF coils, such as temperature control at the winding process.

Journal Articles

Development of a high power diplexer with short-slotted metal half mirrors for electron cyclotron current drive

Saigusa, Mikio*; Atsumi, Kohei*; Yamaguchi, Tomoki*; Oda, Yasuhisa; Sakamoto, Keishi

Fusion Engineering and Design, 88(6-8), p.964 - 969, 2013/10

 Times Cited Count:2 Percentile:20.28(Nuclear Science & Technology)

Journal Articles

Corrosion of austenitic steel in leakage lithium

Furukawa, Tomohiro; Hirakawa, Yasushi; Kato, Shoichi

Fusion Engineering and Design, 88(9-10), p.2502 - 2505, 2013/10

 Times Cited Count:5 Percentile:41.87(Nuclear Science & Technology)

Lithium, which is used as the neutron source of the IFMIF, reacts with oxygen, nitrogen and moisture in atmosphere in case of the leakage accident. In this study, fundamental corrosion test was performed in order to obtain the corrosion behavior of austenitic stainless steel in the estimated lithium compounds. In the experiment, the lithium compounds were filled with the steel into the Tammann pipe made from Al$$_{2}$$O$$_{2}$$, and heated up to 850$$^{circ}$$C. After the test, the specimen was cleaned by alcohol, and then the weight loss measurement and metallurgical examination were performed. Intense corrosion was observed at the environmental conditions containing lithium peroxide. No corrosion was observed in Li$$_{2}$$O environment. According to the consideration based on thermodynamics, Li$$_{2}$$O cannot oxidize iron and lithium is reducing agent. Slight corrosion was observed in LiOH and Li$$_{3}$$N environments.

Journal Articles

Development of a linear motion antenna for the JT-60SA ECRF system

Moriyama, Shinichi; Kobayashi, Takayuki; Isayama, Akihiko; Hoshino, Katsumichi; Suzuki, Sadaaki; Hiranai, Shinichi; Yokokura, Kenji; Sawahata, Masayuki; Terakado, Masayuki; Hinata, Jun; et al.

Fusion Engineering and Design, 88(6-8), p.935 - 939, 2013/10

 Times Cited Count:4 Percentile:35.17(Nuclear Science & Technology)

An antenna having a first mirror driven in the linear motion (LM) and a fixed second mirror was proposed for electron cyclotron range of frequency (ECRF) heating and current drive system, to minimize the risk of cooling-water-leakage. Basic mechanical feasibilities of the bellows covering the movable structures of the antenna were previously investigated using a mock-up. This time, a support structure of the shaft has been designed using a metallic sliding bearing with solid lubricant. The sliding bearing can support combination of linear and rotational motions while a ball bearing supports either linear or rotational motion. We have newly installed the sliding bearing into the mock-up. A vacuum pumping test has been carried out paying attention to the influence of the solid lubricant by mass analysis. To design the LM antenna for JT-60SA in detail, heating and current drive characteristics for typical experimental scenarios of JT-60SA has been investigated by calculation.

Journal Articles

Fabrication and performance test of contact-type liquid level sensor for measuring thickness variation of liquid lithium jet in the IFMIF/EVEDA lithium test loop

Kanemura, Takuji; Kondo, Hiroo; Hoashi, Eiji*; Suzuki, Sachiko*; Yamaoka, Nobuo*; Horiike, Hiroshi*; Furukawa, Tomohiro; Hirakawa, Yasushi; Ida, Mizuho; Matsushita, Izuru*; et al.

Fusion Engineering and Design, 88(9-10), p.2547 - 2551, 2013/10

 Times Cited Count:4 Percentile:35.17(Nuclear Science & Technology)

In the Engineering Validation and Engineering Design Activities (EVEDA) project of the International Fusion Materials Irradiation Facility (IFMIF), thickness variation of a liquid lithium (Li) jet simulating the IFMIF Li target is to be measured in the EVEDA Li Test Loop. This paper presents fabrication and performance tests results of a contact-type liquid level sensor for measuring the jet thickness variation. The sensor can detect contacts between a probe and Li, and analysis of the contact signals yields average jet thickness and amplitude distribution. One of the key fabrication requirements is to drive the probe by 0.1 mm step with positioning precision of 0.01 mm under the vacuum condition of 10$$^{-3}$$Pa. To achieve such requirements, a high torque motor reducer and a friction-reduced ball screw were selected. As a result of the performance tests, the measurement results of the positioning resolution and precision were 0.1 mm and 0.01 mm, respectively.

Journal Articles

Oxidation property and homogenization treatment of plasma sintered beryllides

Kim, Jae-Hwan; Nakamichi, Masaru

Fusion Engineering and Design, 88(9-10), p.2215 - 2218, 2013/10

 Times Cited Count:7 Percentile:52.51(Nuclear Science & Technology)

Journal Articles

Structural analyses of HV bushing for ITER heating NB system

Tobari, Hiroyuki; Inoue, Takashi; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Dairaku, Masayuki; Yamanaka, Haruhiko; Watanabe, Kazuhiro; Sakamoto, Keishi; Kuriyama, Masaaki*; et al.

Fusion Engineering and Design, 88(6-8), p.975 - 979, 2013/10

 Times Cited Count:1 Percentile:11.84(Nuclear Science & Technology)

The HV bushing, one of the ITER NB components, which is to be procured by JADA, is a multi-conductor feed through composed of five-stage double-layered insulator columns with large brazed ceramic ring and fiber reinforced plastic (FRP) ring. The HV bushing is a bulk head between insulation gas at 0.6 MPa and vacuum. The FRP ring is required to sustain the pressure load, seismic load and dead weight. Brazing area of the ceramic ring with Kovar is required to maintain vacuum leak tightness and pressure tightness against the air filled at 0.6 MPa. To design the HV bushing satisfying the safety factor of $$geq$$ 3.5, mechanical analyses were carried out. As for the FRP ring, it was confirmed that isotropic fiber cloth FRP rings should be used for sufficient strength against shear stress. Also, shape and fixation area of the Kovar sleeve were modified to lower the stress at the joint area. As a result, a design of the insulator for the HV bushing was established satisfying the requirement.

Journal Articles

Development of fabrication technologies for advanced tritium breeder pebbles by the sol-gel method

Hoshino, Tsuyoshi

Fusion Engineering and Design, 88(9-10), p.2264 - 2267, 2013/10

 Times Cited Count:16 Percentile:80.14(Nuclear Science & Technology)

Lithium titanate (Li$$_{2}$$TiO$$_{3}$$) has been recognized as a prominent candidate material for use in a tritium breeder. However, the mass of Li$$_{2}$$TiO$$_{3}$$ is decreased over time by Li evaporation in a hydrogen atmosphere, Li burn-up under the high temperatures, and high neutron fluence irradiation found in a DEMO reactor. To compensate for this decrease in mass at high temperatures, Li$$_{2}$$TiO$$_{3}$$ with additional Li (Li$$_{2+x}$$TiO$$_{3+y}$$) have been developed as an advanced tritium breeder. Pebble fabrication using the sol-gel method is one of the promising techniques for the mass production of the advanced tritium breeder pebbles. The authors have been developing a technique of fabricating Li$$_{2+x}$$TiO$$_{3+y}$$ pebbles using the sol-gel method. To increase the density of sintered Li$$_{2+x}$$TiO$$_{3+y}$$ pebbles, the sintering temperature was changed, and at 1473 K, the density of the pebbles was increased to approximately 75%T.D., without any increase in the grain size. This shows the pore size in sintered Li$$_{2+x}$$TiO$$_{3+y}$$ pebbles is decreased by vacuum sintering.

Journal Articles

Trial synthesis of Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ for high-functional tritium breeders

Hoshino, Tsuyoshi; Oikawa, Fumiaki; Natori, Yuri*; Kato, Kenichi*; Sakka, Tomoko*; Nakamura, Mutsumi*; Tatenuma, Katsuyoshi*

Fusion Engineering and Design, 88(9-10), p.2268 - 2271, 2013/10

 Times Cited Count:1 Percentile:11.84(Nuclear Science & Technology)

Lithium titanate with additional Li (Li$$_{2+x}$$TiO$$_{3+y}$$) and lithium orthosilicate (Li$$_{4}$$SiO$$_{4}$$) is one of the most promising candidates for use in a tritium breeder because of its good chemical and mechanical stabilities. Currently, mixtures of tritium breeder pebble and neutron multiplier (Be or Be$$_{12}$$Ti) pebble are being considered for use in increasing the tritium breeding ratio in a breeding blanket. However, lithium and beryllium are gradually reacted under practical operating conditions, and therefore a high-functional tritium breeder such as lithium beryllium oxide (Li$$_{2}$$Be$$_{2}$$O$$_{3}$$) needs to be developed to compensate for this reactive characteristic under high temperature use. In this study, methods of synthesizing Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ have been extensively investigated by means of solid-phase reaction. The solid-phase reaction of LiOH(H$$_{2}$$O) and BeO is a suitable synthesis method for lithium beryllium oxide (Li$$_{2}$$Be$$_{2}$$O$$_{3}$$). It is expected that single-phase Li$$_{2}$$Be$$_{2}$$O$$_{3}$$ will be stable under the mixture conditions of a tritium breeder and neutron multiplier in the blanket region at high temperatures.

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:9 Percentile:61.35(Nuclear Science & Technology)

Journal Articles

Long-pulse production of the negative ion beams for JT-60SA

Kojima, Atsushi; Hanada, Masaya; Yoshida, Masafumi; Inoue, Takashi; Watanabe, Kazuhiro; Taniguchi, Masaki; Kashiwagi, Mieko; Umeda, Naotaka; Tobari, Hiroyuki; Grisham, L. R.*; et al.

Fusion Engineering and Design, 88(6-8), p.918 - 921, 2013/10

 Times Cited Count:6 Percentile:47.59(Nuclear Science & Technology)

In this paper, the recent activities are reported toward demonstration of the long pulse production. As for the improvement of uniform beam current profile, a symmetric magnetic field configuration for the source plasma production, a so-called tent-shaped filter, was found to be effective to improve the uniformity of the beam current profile. A similar configuration is applied to the JT-60 negative ion source whose plasma size is 1220 mm $$times$$ 564 mm. An estimation from trajectory calculations of primary electrons with the symmetric magnetic field configuration showed that the primary electrons were distributed uniformly in a longitudinal direction. As for the temperature control of the plasma grid, a prototype of the grid with cooling/heating by circulating a high-temperature fluorinated fluid has been developed. This grid was found to have a capability to control the temperature with a time constant of 10 s by considering the physical properties of the fluid.

Journal Articles

Re-defining failure envelopes for silicon carbide composites based on damage process analysis by acoustic emission

Nozawa, Takashi; Ozawa, Kazumi; Tanigawa, Hiroyasu

Fusion Engineering and Design, 88(9-10), p.2543 - 2546, 2013/10

 Times Cited Count:15 Percentile:78(Nuclear Science & Technology)

A SiC/SiC composite is a promising candidate for a fusion DEMO blanket. Due to the inherent quasi-ductile failure of composites, determining failure scenario for this class of composites is undoubtedly important to develop design codes in practical use of them. This study aims to evaluate the failure behavior of the quasi-ductile SiC/SiC composites to provide a strength map. For this purpose, detailed tensile, compressive and in-plane shear failure behaviors were evaluated by the acoustic emission (AE) technique. The AE results distinguished damage accumulation processes by wavelet analysis. Of particular emphasis is that matrix cracking occurred prior to the PLS by both tensile and compressive loadings because the rough-surface of SiC fibers resulted in the strong frictional stress at the fiber/matrix (F/M) interface. In this paper, an updated failure envelope will be provided by referring the actual matrix cracking stresses as more realistic and reasonable failure criteria.

Journal Articles

Recent results on tritium technology in JAEA under BA program

Yamanishi, Toshihiko; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu

Fusion Engineering and Design, 88(9-10), p.2272 - 2275, 2013/10

 Times Cited Count:2 Percentile:20.28(Nuclear Science & Technology)

The multi-purpose RI equipment has been constructed at Rokkasho site in DEMO R&D building until 2011. The equipment is the first and unique facility in Japan, where tritium, RI species, and beryllium can simultaneously be used. The amounts of tritium used and stored are 3.7 TBq per day and 7.4 TBq, respectively. The material of the column of the micro gas chromatograph has been studied. The calorimeter has also been studied as a possible tritium measurement method. A set of basic data on the interaction between materials and tritium has been measured especially for pure Fe. As for the tritium behavior in the blanket materials, the tritium release after neutron irradiation was studied. As a study for the tritium durability, the endurance of ion exchange membrane has been tested by using high concentration tritium water. The data of tritium water were well consistent with those obtained by $$gamma$$ irradiation.

Journal Articles

Adsorption rate of hydrogen isotopes on Ca-mordenite

Kawamura, Yoshinori; Edao, Yuki; Yamanishi, Toshihiko

Fusion Engineering and Design, 88(9-10), p.2255 - 2258, 2013/10

 Times Cited Count:8 Percentile:57.25(Nuclear Science & Technology)

To develop an adsorbent that is suitable for a separation column of gas chromatograph for hydrogen isotope analysis, the mordenite-type zeolite of which cations (Na$$^{+}$$) were exchanged with other cations have been prepared and their hydrogen isotope adsorption behavior is being investigated. Then, it has been shown experimentally that mordenite-type zeolite of which cation has been exchanged with Ca$$^{2+}$$ (Ca-MOR) has fairly large adsorption capacity. So, breakthrough curves of H$$_{2}$$ (or D$$_{2}$$) adsorption on Ca-MOR at 194 K and 175 K have been observed and mass transfer coefficients have been estimated from them. The rate-controlling step of hydrogen adsorption is hydrogen diffusion in porous adsorbent. And, isotopic difference of effective diffusivity in Ca-MOR is larger than that in Na-MOR. Therefore, in comparison with Na-MOR, use of Ca-MOR is expected to enhance the hydrogen isotope separation capability.

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:20.28(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.

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