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Journal Articles

A Proposal of ITER vacuum vessel fabrication specification and results of the full-scale partial mock-up test

Nakahira, Masataka; Takeda, Nobukazu; Kakudate, Satoshi; Onozuka, Masanori*

Fusion Engineering and Design, 83(10-12), p.1578 - 1582, 2008/12

 Times Cited Count:4 Percentile:31(Nuclear Science & Technology)

The structure and fabrication methods of the ITER vacuum vessel have been investigated and defined by the ITER international team. However, some of the current specifications are very difficult to be achieved from the manufacturing point of view and will lead to cost increase. This report summarizes the Japanese proposed specification of the VV mock-up describing differences between the ITER supplied design. A series of the fabrication and assembly procedures for the mock-up are presented in this report, together with candidates of welding configurations. Finally, the report summarizes the results of mock-up fabrication, including results of non-destructive examination of weld lines, obtained welding deformation and issues revealed from the fabrication experience.

Journal Articles

Basic analysis of weldability and machinability of structural materials for ITER toroidal field coils

Onozuka, Masanori*; Shimizu, Katsusuke*; Urata, Kazuhiro*; Kimura, Masahiro*; Kadowaki, Hirokazu*; Okamoto, Mamoru*; Nakajima, Hideo; Hamada, Kazuya; Okuno, Kiyoshi

Fusion Engineering and Design, 82(5-14), p.1431 - 1436, 2007/10

 Times Cited Count:2 Percentile:19.35(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Demonstration tests for manufacturing the ITER vacuum vessel

Shimizu, Katsusuke*; Onozuka, Masanori*; Usui, Yukinori*; Urata, Kazuhiro*; Tsujita, Yoshihiro*; Nakahira, Masataka; Takeda, Nobukazu; Kakudate, Satoshi; Omori, Junji; Shibanuma, Kiyoshi

Fusion Engineering and Design, 82(15-24), p.2081 - 2088, 2007/10

 Times Cited Count:5 Percentile:38.7(Nuclear Science & Technology)

To confirm the manufacturing and assembly process of the ITER vacuum vessel (VV), a series of related tests has been conducted. (1) Using a full-scale partial mock-up, fabrication methods are to be examined to determine feasibility. (2) To simulate a series of field-joint assembly operations, a test stand was built. (3) To provide an appropriate shield gas supply on the back side of the outer shell during field-joint welding, three types of back-seal structures have been tested. (4) The applicability of UT methods for volumetric inspection has been investigated. (5) Applicability of Liquid Penetrant Testing as a surface examination for the VV interior surface (i.e. ultra-vacuum side) has been investigated.

Journal Articles

Comprehending the vacuum vessel structure

Onozuka, Masanori*; Nakahira, Masataka

Purazuma, Kaku Yugo Gakkai-Shi, 82(9), p.599 - 608, 2006/09

The Vacuum Vessel maintains ultra high vacuum required for plasma containment. This paper shows functions, conditions required to achieve the functions and examples of structural concepts of the Vacuum Vessel. The topic outlines structural standards required for the design, an example of general design procedure and structural design of ITER Vacuum Vessel which is proceeded for construction are also explained in the paper.

JAEA Reports

Study on assembly techniques and procedures for ITER tokamak device

Obara, Kenjiro; Kakudate, Satoshi; Shibanuma, Kiyoshi; Sago, Hiromi*; Ue, Koichi*; Shimizu, Katsusuke*; Onozuka, Masanori*

JAEA-Technology 2006-034, 85 Pages, 2006/06

JAEA-Technology-2006-034.pdf:9.18MB

The International Thermonuclear Experimental Reactor (ITER) tokamak is composed of many kinds of components. The dimensions and weight of the respective components are around a few ten-meters and several hundred-tons. In addition, the whole tokamak assembly, which are composed of these components, are roughly estimated, 26 m in diameter, 18 m in height and over 16,500 tons in total weight. On the other hand, as for positioning and assembly tolerances of these components are required to be a high accuracy of $$pm$$3mm in spite of large size and heavy weight. The assembly procedures and techniques of the ITER tokamak are therefore studied, taking account of the tolerance requirements. Based on the above background, the assembly procedures and techniques, which are able to assemble the tokamak with high accuracy, are described in the present report. The following newly developed tokamak assembly procedures and techniques, jigs and tools for assembly and metrology concept based on the available knowledge and experiences of the installation of the large components, in order to improve the IT (International Team) design toward the more realistic one. As a result, we show the realistic tokamak assembly procedures and techniques to be able to assemble the large and heavy ITER tokamak with high accuracy. (1)Assembly and alignment of the toroidal field coil with high accuracy. (2)Simplification of the assembly procedures, and the jigs/tools and procedures to reduce the misalignment. (3)Assembly procedures and techniques for the vacuum vessel to reduce the weld distortion. (4)Supporting procedures and techniques of the vacuum vessel sector to prevent the toridal field coil from the deformation due to the dead weight of the vacuum vessel sector. (5)Datum points and lines for the required positions and assembly tolerances during tokamak assembly.

JAEA Reports

Applicability assessment of plug weld to ITER vacuum vessel by crack propagation analysis

Omori, Junji; Nakahira, Masataka; Takeda, Nobukazu; Shibanuma, Kiyoshi; Sago, Hiromi*; Onozuka, Masanori*

JAEA-Technology 2006-017, 134 Pages, 2006/03

JAEA-Technology-2006-017.pdf:15.96MB

In order to improve the fabricability of the vacuum vessel (VV) of International Thermonuclear Experimental Reactor (ITER), applicability of plug weld between VV outer shell and stiffening ribs/blanket support housings has been assessed using crack propagation analysis for the plug weld. The ITER VV is a double-wall structure of inner and outer shells with ribs and housings between the shells. For the fabrication of VV, ribs and housings are welded to outer shell after welding to inner shell. A lot of weld grooves should be adjusted for the outer shell weld. The plug weld can allow larger tolerance of weld groove gaps than ordinary butt weld. However, un-welded lengths parallel to outer shell surface remain in the plug weld region. It is necessary to evaluate the allowable un-welded length to apply the plug weld to ITER vacuum vessel fabrication. For the assessment the allowable un-welded lengths have been calculated by crack propagation analyses for the load conditions, conservatively assuming the un-welded region is a crack. The analyses have been carried out for typical inboard straight region and inboard upper curved region with maximum housing stress. The allowable cracks of ribs are estimated to be 8.8mm and 38mm for the rib and the housing, respectively, considering inspection error of 4.4mm. Plug welding for welding between outer shell and ribs/housings could be applicable.

Journal Articles

ITER nuclear components, preparing for the construction and R&D results

Ioki, Kimihiro*; Akiba, Masato; Barabaschi, P.*; Barabash, V.*; Chiocchio, S.*; Daenner, W.*; Elio, F.*; Enoeda, Mikio; Ezato, Koichiro; Federici, G.*; et al.

Journal of Nuclear Materials, 329-333(1), p.31 - 38, 2004/08

 Times Cited Count:13 Percentile:65.42(Materials Science, Multidisciplinary)

The preparation of the procurement specifications is being progressed for key components. Progress has been made in the preparation of the procurement specifications for key nuclear components of ITER. Detailed design of the vacuum vessel (VV) and in-vessel components is being performed to consider fabrication methods and non-destructive tests (NDT). R&D activities are being carried out on vacuum vessel UT inspection with waves launched at an angle of 20 or 30 degree, on flow distribution tests of a two-channel model, on fabrication and testing of FW mockups and panels, on the blanket flexible support as a complete system including the housing, on the blanket co-axial pipe connection with guard vacuum for leak detection, and on divertor vertical target prototypes. The results give confidence in the validity of the design and identify possibilities of attractive alternate fabrication methods.

Journal Articles

Numerical evaluation of experimental models to investigate the dynamic behavior of the ITER tokamak assembly

Onozuka, Masanori*; Takeda, Nobukazu; Nakahira, Masataka; Shimizu, Katsusuke*; Nakamura, Tomomichi*

Fusion Engineering and Design, 69(1-4), p.757 - 762, 2003/09

 Times Cited Count:2 Percentile:19.48(Nuclear Science & Technology)

The dynamic behavior of the ITER tokamak assembly has been investigated. Three experimental models have been considered to validate the numerical analysis methods for the dynamic events, mainly seismic events. A 1/8-scaled tokamak model, which is based on the 1998 ITER design, is under construction. Non-linear vibration characteristics, such as damping, can only be identified by a full-scale model. Therefore, a full-scale gravity support structure for the coil system has been designed and will be tested. In addition, for the sub-scaled tokamak model, the VV is assumed to be a rigid structure. This assumption is to be verified using a 1/20-scaled model. The above experimental models and their testing conditions have analytically and numerically evaluated. For example, both the static and dynamic spring constants obtained by static analysis and eigen-value analysis, respectively, were evaluated to be in good agreement.

Journal Articles

Design and thermal/hydraulic characteristics of the ITER-FEAT vacuum vessel

Onozuka, Masanori*; Ioki, Kimihiro*; Sannazzaro, G.*; Utin, Y.*; Yoshimura, Hideto*

Fusion Engineering and Design, 58-59, p.857 - 861, 2001/11

 Times Cited Count:15 Percentile:72.41(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Manufacturing and maintenance technologies developed for a thick-wall structure of the ITER vacuum vessel

Onozuka, Masanori*; Alfile, J. P.*; Aubert, P.*; Dagenais, J.-F.*; Grebennikov, D.*; Ioki, Kimihiro*; Jones, L.*; Koizumi, Koichi; Krylov, V.*; Maslakowski, J.*; et al.

Fusion Engineering and Design, 55(4), p.397 - 410, 2001/09

 Times Cited Count:25 Percentile:85.18(Nuclear Science & Technology)

Development of welding, cutting and non-destructive testing (NDT) techniques, and development of remotized systems, have been conducted for on-site manufacturing and maintenance of the thick wall structure of the ITER vacuum vessel (VV). Conventional techniques, including TIG (tungsten inert gas) welding, plasma cutting and ultrasonic inspection, have been improved and optimized for the application to thick austenitic stainless steel plates. In addition, advanced methods have been investigated including reduced-pressure electron-beam and multi-pass NdYAG (neodymium-doped yttrium aluminum garnet) laser welding, NdYAG laser cutting, and EMAT (electro-magnetic acoustic transducer) inspection to improve cost and technical performance. Two types of remotized systems with different payloads have been investigated and one of them has been fabricated and demonstrated in field joint welding, cutting, and NDT tests on test mockups and full-scale ITER VV sector models. The progress and results of this development to date provide a high level of confidence that the manufacturing and maintenance of the ITER VV is feasible.

Journal Articles

Progress and achievements on the R&D activities for ITER vacuum vessel

Nakahira, Masataka; Takahashi, Hiroyuki*; Koizumi, Koichi; Onozuka, Masanori*; Ioki, Kimihiro*

Nuclear Fusion, 41(4), p.375 - 380, 2001/04

 Times Cited Count:5 Percentile:18.85(Physics, Fluids & Plasmas)

no abstracts in English

Journal Articles

Design and analysis of the vacuum vessel for RTO/RC-ITER

Onozuka, Masanori*; Ioki, Kimihiro*; Johnson, G.*; Kodama, T.*; Sonnazzaro, G.*; Utin, Y.*

Fusion Engineering and Design, 51-52(Part.B), p.249 - 255, 2000/11

 Times Cited Count:5 Percentile:38.4(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Evaluation of welding deformation on ITER vacuum vessel

Nakahira, Masataka; Takahashi, Hiroyuki*; Inoue, O.*; Koizumi, Koichi; Shibanuma, Kiyoshi; Tada, Eisuke; Onozuka, Masanori*; Ioki, Kimihiro*

Proceedings of the 18th IEEE/NPSS Symposium on Fusion Engineering (SOFE '99), p.245 - 248, 1999/00

no abstracts in English

Journal Articles

Fabrication and assembly of full-scale sector models for ITER vacuum vessel

Koizumi, Koichi; Nakahira, Masataka; Oka, Kiyoshi; *; Takahashi, Hiroyuki*; Tada, Eisuke; Ioki, Kimihiro*; Johnson, G.*; Onozuka, Masanori*; Y.Utin*; et al.

Fusion Technology, 34(3), p.586 - 590, 1998/11

no abstracts in English

Journal Articles

Development of a compact W-shaped pumped divertor in JT-60U

Sakurai, Shinji; Hosogane, Nobuyuki; Masaki, Kei; ; ; *; *; Shimizu, Katsuhiro; Akino, Noboru; Miyo, Yasuhiko; et al.

Fusion Engineering and Design, 39-40, p.371 - 376, 1998/00

 Times Cited Count:5 Percentile:44.99(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Design progress of the vacuum vessel for ITER

Onozuka, Masanori*; Johnson, G.*; Ioki, Kimihiro*; Sonnazzaro, G.*; Y.Utin*; *; ; R.Parker*; Koizumi, Koichi; E.Kuzmin*; et al.

Proc. of 17th IEEE/NPSS Symposium Fusion Engineering (SOFE'97), p.1013 - 1016, 1998/00

no abstracts in English

Journal Articles

Fabrication of full-scale sector model for ITER vacuum vessel

Koizumi, Koichi; Nakahira, Masataka; *; Takahashi, Hiroyuki*; Tada, Eisuke; Ioki, Kimihiro*; Johnson, G.*; Onozuka, Masanori*; Y.Utin*; Sonnazzaro, G.*; et al.

Proc. of 17th IEEE/NPSS Symposium Fusion Engineering (SOFE'97), 2, p.933 - 936, 1998/00

no abstracts in English

Journal Articles

Electrical insulation and conduction coating for fusion experimental devices

Onozuka, Masanori*; Tsujimura, Seiji*; Toyoda, Masahiko*; Inoue, Masahiko*; Abe, Tetsuya; Murakami, Yoshio

Fusion Technology, 29(1), p.73 - 82, 1996/01

 Times Cited Count:9 Percentile:63.02(Nuclear Science & Technology)

no abstracts in English

Journal Articles

Design of a compact W-shaped pumped divertor in JT-60U

Sakurai, Shinji; Hosogane, Nobuyuki; ; Masaki, Kei; ; *; *; Takahashi, Shoryu*; Saido, Masahiro; Inoue, Masahiko*; et al.

Fusion Technology 1996, 0, 4 Pages, 1996/00

no abstracts in English

Journal Articles

Development of electrical insulation and conduction coating for fusion experimental devices

Onozuka, Masanori*; Tsujimura, Seiichi*; Toyoda, Masahiko*; Inoue, Masahiko*; Abe, Tetsuya; Murakami, Yoshio

Fusion Technology 1994, Vol.1, p.803 - 806, 1995/00

no abstracts in English

30 (Records 1-20 displayed on this page)