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Yamada, Tomonori; Takebe, Toshihiko*; Ishizuka, Ippei*; Daido, Hiroyuki*; Hanari, Toshihide; Shibata, Takuya; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; et al.
Journal of Nuclear Science and Technology, 56(12), p.1171 - 1179, 2019/12
Times Cited Count:1 Percentile:9.69(Nuclear Science & Technology)We describe a new chipping technique combined with a water-jet technique as one of the candidate techniques for the retrieval of fuel debris and support structures as part of the decommissioning of the Fukushima Daiichi Nuclear Power Station. We performed proof-of-principle experiments to demonstrate the removal capability of metal parts, where we focused on the observation of removal processes from a metallic sample using a 5.5-kW continuous wave fiber laser combined with continuous and pulsed water jets.
Furusawa, Akinori; Nishimura, Akihiko; Takebe, Toshihiko*; Nakamura, Masaki*; Takenaka, Yusuke*; Saijo, Shingo*; Nakamoto, Hiroyuki*
E-Journal of Advanced Maintenance (Internet), 9(2), p.44 - 51, 2017/08
The aim of this work is to investigate the applicability of ultrasonic guided wave for evaluation of laser beam butt-welding quality. Ten in total test pipes having welding seam is prepared. Two piece of pipe are jointed and continuous laser beam is irradiated on the edges, varying laser irradiation power, welding side and surface profile of the adjacent edges of the pipe. Ultrasonic guided wave testing experiment is performed on the pipes. Torsional mode guided wave is excited by EMAT. The experimental results are analyzed and issues are discussed. The reflection wave bullet from the poor interface of the welding seam is clearly observed, whereas no reflection from fine welded line. From the aspect of laser irradiation power, welding side and surface profile of the adjacent edges, the relation between the interface condition and detection wave bullet are analyzed. It is found that the ultrasonic guided wave technologies have the potential for evaluating laser beam butt-welding seam.
Hanari, Toshihide; Takebe, Toshihiko*; Yamada, Tomonori; Daido, Hiroyuki; Ishizuka, Ippei*; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*
Proceedings of 2017 International Congress on Advances in Nuclear Power Plants (ICAPP 2017) (CD-ROM), 3 Pages, 2017/04
In decommissioning of Fukushima Daiichi Nuclear Power Station, a retrieval process of fuel debris in the Primary Containment Vessel by a remote operation is one of the key issues. In this process, prevention of spreading radioactive materials is one of the important considerations. Furthermore, an applicable technique to the process requires keeping of reasonable processing-efficiency. We propose to use the combined technique including a laser light and a water jet as a retrieval technique of the fuel debris. The laser processing technique combined with a repetitive pulsed water jet could perform an efficient retrieval processing. Our experimental result encourages us to promote further development of the technique towards a real application at Fukushima Daiichi Nuclear Power Station.
Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Nguyen, P. L.; Matsunaga, Yukihiro
JAEA-Research 2014-018, 41 Pages, 2014/09
In decommissioning works of the Fukushima Daiichi Nuclear Power Plants, it is required that fuel debris solidifying mixed materials of fuels and in-vessel structures should be removed. The fuel debris is considered to have characteristics, such as indefinite shapes, porous bodies, multi-compositions, higher hardness, etc. from the knowledge in the U.S. and the Three Mile Island nuclear power plant. Laser lights are characterized by higher power density, local processability, remote controllabilitiy, etc. and can be performed thermal cutting and crushing-up for various materials which does not depend on fracture toughness. This report describes a research program and research activities in FY2013 aiming at developing removal system of fuel debris by the use of laser lights.
Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro
JAEA-Research 2013-024, 49 Pages, 2013/08
In decommissioning works of the Fukushima Daiichi Nuclear Power Plants, it is required that fuel debris solidifying mixed materials of fuels and in-vessel structures should be removed. The fuel debris is considered to have characteristics, such as indefinite shapes, porous bodies, multi-compositions, higher hardness, etc. from the knowledge in the U.S. and the Three Mile Island nuclear power plant. Laser lights are characterized by higher power density, local processability, remote controllabilitiy, etc. and can be performed thermal cutting and crushing-up for various materials which does not depend on fracture toughness. This report describes a research program and research activities in FY2012 aiming at developing removal system of fuel debris by the use of laser lights.
Iihara, Junji*; Muramatsu, Yasuji; Takebe, Toshihiko*; Sawamura, Akitaka*; Namba, Akihiko*; Imai, Takahiro*; Denlinger, J. D.*; Perera, R. C. C.*
Japanese Journal of Applied Physics, Part 1, 44(9A), p.6612 - 6617, 2005/09
Times Cited Count:12 Percentile:42.88(Physics, Applied)Electronic structure transition between semiconducting and metallic states in boron (B) -doped diamonds was element-selectively observed by soft X-ray emission and absorption spectroscopy using synchrotron radiation. For the lightly B-doped diamonds, the B 2-density of states (DOS) in the valence band were enhanced with a steep-edge-feature near the Fermi level, and localized acceptor levels, characteristic of semiconductors, were clearly observed both in B 2- and C 2-DOS in the conduction bands. For the heavily B-doped diamonds, the localized acceptor levels developed into extended energy levels and new energy levels were generated to form an extended conduction band structure which overlapped with the valence band. Thus, this clarified that the metallic energy band structure is actually formed by heavy boron doping. Such valence and conduction band structures observed by soft X-ray emission and absorption spectroscopy well accounted for the electrical properties of the B-doped diamonds.
Onuki, Toshihiko; Takebe, Shinichi; Yamamoto, Tadatoshi
Journal of Nuclear Science and Technology, 26(8), p.795 - 804, 1989/08
no abstracts in English
村松 壽晴; 山田 知典; 羽成 敏秀; 武部 俊彦; 松永 幸大
酒井 英明*; 碓井 秀三*; 中田 正宏*; 坪井 昭彦*; 社本 英泰*
【課題】異なる材料が混在して、無定形で不規則な外形を有する処理対象物を、その材料に対応して溶断あるいは破砕できるレーザー光を用いた溶断・破砕適応制御装置を提供する。 【解決手段】レーザー加工ヘッド6を搭載したロボット1、対象物19の状態を検出する検出部3、検出情報に基づいてロボット1を制御する制御部2を備え、検出部3は対象物19からのレーザー光8の反射光25を受光し、反射光25に基づいて対象物19の形状を認識するレーザースキャナ12、反射光25に基づいて対象物19の材質を検出する分光計1と、反射光25に基づいて対象物19の溶断の有無を検出する温度計13を有し、制御部2は検出部3からの情報に基づいて、ロボットをするロボット制御部と、レーザー光8を制御するレーザー光制御部9を有している。
Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu
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Hanari, Toshihide; Matsunaga, Yukihiro; Takebe, Toshihiko; Yamada, Tomonori; Muramatsu, Toshiharu
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Takebe, Toshihiko; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu
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Hanari, Toshihide; Takebe, Toshihiko; Yamada, Tomonori; Muramatsu, Toshiharu
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Nguyen, P. L.; Takebe, Toshihiko; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu
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Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu
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In the decommissioning of the Fukushima Daiichi NPPs, remote handling techniques are necessary to remove the fuel debris which is solidified by mixed molten materials composed of fuels and in-vessel structures. In terms of remote handling, a laser beam can penetrate a narrow gap and it can shoot the substance without reactive force. Thus, a laser has been expected as one of the useful decommissioning tools. In this paper, to evaluate the cutting and crushing performances, we performed thick metal cutting and ceramics crushing using a fiber laser. A continuous wave mode and pulsed mode make it possible to cut a 30 mm thick SS400 steel plate and to crush a 10 mm thick alumina pellet. Moreover, we succeeded to cut a metal-ceramic mixture materials using fiber laser, in combination with x-y-z tri-axes control system and laser scanner. It is hoped that the outcome of the present study would be of some use to develop remote cutting and crushing technique for the decommissioning.
Takebe, Toshihiko*; Hanari, Toshihide; Yamada, Tomonori; Daido, Hiroyuki; Ishizuka, Ippei*; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*
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no abstracts in English
Hanari, Toshihide; Takebe, Toshihiko*; Yamada, Tomonori; Daido, Hiroyuki; Ishizuka, Ippei*; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*
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Ishizuka, Ippei*; Takebe, Toshihiko*; Yamada, Tomonori; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*; Shibata, Takuya
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Yamada, Tomonori; Ishizuka, Ippei*; Takebe, Toshihiko*; Hanari, Toshihide; Omori, Shinya*; Kurosawa, Koichi*; Sasaki, Go*; Nakada, Masahiro*; Sakai, Hideaki*; Shibata, Takuya; et al.
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Takebe, Toshihiko; Matsunaga, Yukihiro; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu
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Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.
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no abstracts in English