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Journal Articles

Development of a laser chipping technique combined with water jet for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

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:17.7(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.

Journal Articles

Ultrasonic guided wave approach for inspecting concave surface of the laser butt-welded pipe

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.

Journal Articles

Demonstration of laser processing technique combined with water jet technique for retrieval of fuel debris at Fukushima Daiichi Nuclear Power Station

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.

JAEA Reports

Research on removal technologies of fuel debris and in-vessel structures using laser light (II); Research activities on FY2013

Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Nguyen, P. L.; Matsunaga, Yukihiro

JAEA-Research 2014-018, 41 Pages, 2014/09

JAEA-Research-2014-018.pdf:42.21MB

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.

JAEA Reports

Research on removal technologies of fuel debris and in-vessel structures using laser light (I); Research plan and research activities on FY2012

Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro

JAEA-Research 2013-024, 49 Pages, 2013/08

JAEA-Research-2013-024.pdf:6.63MB

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.

Journal Articles

Element-selective observation of electronic structure transition between semiconducting and metallic states in boron-doped diamond using soft X-ray emission and absorption spectroscopy

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:44.36(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$$p$$-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$$p$$- and C 2$$p$$-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.

Journal Articles

Development of migration prediction system(MIGSTEM) for cationic species of radionuclides through soil layers

Onuki, Toshihiko; Takebe, Shinichi; Yamamoto, Tadatoshi

Journal of Nuclear Science and Technology, 26(8), p.795 - 804, 1989/08

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 5; Characteristics of geometry recognition performance for laser scanning device in laser cutting processes

Yamada, Tomonori; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 1; Outline of the study

Muramatsu, Toshiharu; Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 4; Evaluation of laser cutting and crushing characteristics by an XYZ triaxial robot

Takebe, Toshihiko; Matsunaga, Yukihiro; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 2; Characteristic evaluation of metal cutting by laser continuous irradiation and assist gas flow

Hanari, Toshihide; Matsunaga, Yukihiro; Takebe, Toshihiko; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 9; Generalization of influence factor on high powered fiber laser cutting performance

Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 6; Experiment of laser cutting and crushing of randomly-shaped / metal-ceramics composite

Takebe, Toshihiko; Hanari, Toshihide; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 8; Study on the improvement of metal cutting performance by modulated assist gas jet flows

Hanari, Toshihide; Takebe, Toshihiko; Yamada, Tomonori; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Laser cutting and crushing for indefinite shape materials

Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 12; Response surface method of underwater laser cutting performance

Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

Oral presentation

Evaluation of fiber laser cutting and crushing applied to the removal technology of fuel debris and in-vessel structures

Yamada, Tomonori; Hanari, Toshihide; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu

no journal, , 

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.

Oral presentation

Study on removal technologies for Fukushima's fuel debris using laser light, 13; Characteristic evaluation of optical signal emitted from molten metal during laser cutting process

Hanari, Toshihide; Yamada, Tomonori; Takebe, Toshihiko; Matsunaga, Yukihiro; Nguyen, P. L.; Muramatsu, Toshiharu

no journal, , 

no abstracts in English

26 (Records 1-20 displayed on this page)