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Journal Articles

Numerical simulation of laser welding different kinds of materials using a thermohydraulics computational science numerical simulation code SPLICE

Muramatsu, Toshiharu; Sato, Yuji; Kamei, Naomitsu; Aoyagi, Yuji*; Shobu, Takahisa

Nippon Kikai Gakkai Dai-13-Kai Seisan Kako, Kosaku Kikai Bumon Koenkai Koen Rombunshu (No.19-307) (Internet), p.157 - 160, 2019/10

no abstracts in English

Journal Articles

Development on laser cutting technique to suppress spatter particles aiming at disposal of radio-active waste

Naoe, Takashi; Teshigawara, Makoto; Futakawa, Masatoshi; Mizutani, Haruki; Muramatsu, Toshiharu; Yamada, Tomonori; Ushitsuka, Yuji*; Tanaka, Nobuatsu*; Yamasaki, Kazuhiko*

Proceedings of 8th International Congress on Laser Advanced Materials Processing (LAMP 2019) (Internet), 5 Pages, 2019/05

Laser cutting is one of the options in the disposal of radio-active waste, such as spallation neutron target vessel in J-PARC, etc. Due to unique characteristic of laser, such as non-contact system, it is more easily to provide remote-controlled system in comparison with conventional one, such as mechanical cutting machine, etc. However, a demerit of laser cutting is the sputter and fume caused by laser cutting, resulting in contamination with radio-active materials its surroundings. Recently it was developed that the spatter suppression technique by controlling laser beam profile in laser welding process. In order to apply this suppression technique to laser cutting, first of all, we attempted to observe the phenomenon at melting area during laser cutting using a high-speed video camera in order to make the physical model. The result showed that the appearance of fume and sputter were independently confirmed in the time evolution.

Journal Articles

Potential for remote controllable systematization of the method of testing reinforced concrete using guided-wave on rebar

Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke; Muramatsu, Toshiharu

Proceedings of International Topical Workshop on Fukushima Decommissioning Research (FDR 2019) (Internet), 4 Pages, 2019/05

The aim of this work presented here is to demonstrate the potential of our method for remote controllable systematization, of testing reinforced concrete based on ultrasonic guided-wave on rebar. In order to investigate how the deteriorated phenomena has the effects on the ultrasonic guided-wave propagating on the rebar, following experiments are conducted. Test pieces used for the experiments are made of bare steel rod and cylindrically pored mortar to be representing the actual reinforced concrete. Irradiating the end face of the rod with nanosecond pulsed laser makes the ultrasonic guided-wave induced, at the other end face, the guided wave signal is measured with ultrasonic receiver. One test piece is with no damage and the other is deteriorated test piece. The deterioration is made by electrolytic corroded method. The guided-wave signal from the deteriorated test piece is measured with respect to each energization time, the change in the waveform is investigated. Analyzing the results from the experiments above, it is found that the deterioration of rebar has remarkable effects on the guided-wave signal. The signal from test piece with no damage has strong peak at both specific frequency and lower region, on the other hand, signals from deteriorated test piece has only at the specific frequency depending on the diameter of the steel rod. Finally, discussion concerning with the experimental results and future perspective for remote controllable systematization of our method is carried out.

Journal Articles

Provision of laser irradiation conditions for melting and solidification processes using computational science simulation code SPLICE

Muramatsu, Toshiharu

Sumato Purosesu Gakkai-Shi, 8(1), p.4 - 8, 2019/01

no abstracts in English

Journal Articles

Provision of laser irradiation conditions for melting and solidification processes using computational science simulation code SPLICE

Muramatsu, Toshiharu

Nippon Kikai Gakkai 2018-Nendo Nenji Taikai Koen Rombunshu (DVD-ROM), 5 Pages, 2018/09

A general-purpose three-dimensional thermohydraulics computer science simulation code SPLICE was developed at JAEA and designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications. The results obtained from various numerical simulations using the SPLICE code are very encouraging in the sense that the SPLICE code would be used as one of the efficient front-loading tools to reduce overhead loads in laser processing.

Journal Articles

Computational science simulations for laser coating processes

Muramatsu, Toshiharu

Reza Kako Gakkai-Shi, 25(2), p.81 - 85, 2018/06

no abstracts in English

Journal Articles

Evaluation of melting and solidification processes by laser irradiations using a computational science simulation code SPLICE

Muramatsu, Toshiharu

Dai-89-Kai Reza Kako Gakkai Koen Rombunshu, p.115 - 119, 2018/05

no abstracts in English

Journal Articles

Establishment of Fukui Smart Decommissioning Technology Demonstration Base; Decommissioning Technology Demonstration Test Center (tentative name)

Muramatsu, Toshiharu; Sano, Kazuya; Terauchi, Makoto

Dekomisshoningu Giho, (57), p.65 - 74, 2018/03

The Decommissioning Technology Demonstration Test Center (tentative name) is established as a central facility of "Fukui Smart Decommissioning Technology Demonstration Base" which was adopted by the support policy "Regional Science and Technology Demonstration Base Establishment Project" of the Ministry of Education, Culture, Sports, Science and Technology in FY 2016 supplementary budget. This facility is a base to train local companies about technology concerning the decommissioning of nuclear power plants and for the industry, academia and government to contribute to the development of the regional economy and solving the problem of decommissioning under one roof, and consists of decommissioning dismantling technology verification field, laser processing advanced field and decommissioning mock-up test field. The papers introduce the outline of the facilities in each of these fields.

Journal Articles

Computational science simulation of laser material processing

Muramatsu, Toshiharu

Hikari Araiansu, 28(12), p.31 - 35, 2017/12

no abstracts in English

Journal Articles

Front-loading for metal powder additive manufacturing processes with a computational science simulation code SPLICE

Muramatsu, Toshiharu; Aoyagi, Yuji*; Yoshiuji, Takahiro*

Nippon Kikai Gakkai 2017-Nendo Nenji Taikai Koen Rombunshu (DVD-ROM), 4 Pages, 2017/09

A general-purpose three-dimensional thermohydraulics numerical simulation code SPLICE was developed at Japan Atomic Energy Agency and designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications, such as welding, coating, cutting, etc. The result obtained from metal powder laser additive manufacturing simulations is very encouraging in the sense that the SPLICE code would be used as one of efficient tools to provide the laser irradiation conditions.

Journal Articles

Industry development activities and applied laser research activities at Fukui branch of Japan Atomic Energy Agency

Furusawa, Akinori; Takenaka, Yusuke*; Nishimura, Akihiko; Mizutani, Haruki; Muramatsu, Toshiharu

Nippon Hozen Gakkai Dai-14-Kai Gakujutsu Koenkai Yoshishu, p.479 - 480, 2017/08

Industry development activities on applied laser research held at Fukui branch of Japan Atomic Energy Agency are reported. Industry development is inevitable in long-term vision and strategy for developing maintenance technology and establishing decommissioning technology. Fukui branch of JAEA has organized public seminar offering businesses to promote these activities and technology exchange for years. Here some examples offered in the current seminar are introduced concerning with laser technology. Finally, our goal and important point of view are discussed.

Journal Articles

Computational science simulations of laser coating processes using a metal powder direct injection system

Muramatsu, Toshiharu

Reza Kenkyu, 44(12), p.799 - 803, 2016/12

no abstracts in English

Journal Articles

Computational science simulation of laser material processing and provision of their irradiation conditions

Muramatsu, Toshiharu

KANRIN, 68, p.14 - 18, 2016/09

no abstracts in English

Journal Articles

Front-loading method for laser processing of metallic materials with a digital mock-up system

Muramatsu, Toshiharu

Dai-84-KaiReza Kako Gakkai Koen Rombunshu, p.113 - 116, 2016/01

A general-purpose three-dimensional thermohydraulics numerical simulation code SPLICE was developed at Japan Atomic Energy Agency and designed to deal with gas-liquid-solid consolidated incompressible viscous flows with a phase change process in various laser applications, such as welding, coating, cutting, etc. The result obtained from laser coating simulations is very encouraging in the sense that the SPLICE code would be used as one of efficient front-loading tools for related to the laser coating processes.

Journal Articles

Computational science simulation of laser materials processing and provision of their irradiation conditions

Muramatsu, Toshiharu

RIST News, (60), p.22 - 27, 2016/01

no abstracts in English

JAEA Reports

A Study on laser welding of ferritic/martensitic steel (PNC-FMS) for fast reactor fuel assemblies

Kono, Fumiaki; Sogame, Motomu; Yamada, Tomonori; Shobu, Takahisa; Naganuma, Masayuki; Ozawa, Takayuki; Muramatsu, Toshiharu

JAEA-Technology 2015-004, 57 Pages, 2015/03

JAEA-Technology-2015-004.pdf:20.87MB

Laser welding of ferritic/martensitic steel (PNC-FMS) sheets with different thicknesses (2 mm and 5 mm) was examined to investigate the weldability between the inner and outer duct in fast reactor fuel assemblies with inner duct structure (FAIDUS); the objective of the inner duct is to avoid the re-criticality in case of the core melting accident. Laser-spot and melt-run welding was performed at various laser powers, welding times and velocities to find out the appropriate welding conditions with few defects and enough penetration depth. As for the spot welding, furthermore, slow cooling rate or pulsed laser irradiation could reduce the crack and porosity in the welded zone. The strain of the welded zone almost disappeared and the hardness was comparable with that of the base metal by applying post welding heat treatment at 690 $$^{circ}$$C for 103 min. In addition, the shear strength of welded joints was confirmed to be sufficiently higher than the provisional allowance shear stress. These results indicate that laser welding would be probably applied to the PNC-FMS inner and outer ducts.

JAEA Reports

Research on interaction of laser light and non-metals; Evaluation of laser irradiation behavior to concrete

Yamada, Tomonori; Muramatsu, Toshiharu

JAEA-Research 2014-026, 28 Pages, 2015/02

JAEA-Research-2014-026.pdf:18.03MB

In this study the response of hardened cement pastes, which is a major component of concrete, to laser irradiation was investigated under various experimental conditions aiming at the future application to "laser-processing" of concrete. (1) Evaluation of water-cement ratio for laser irradiation. It was found that hardened cement paste subjected to laser irradiation explodes very easily to be hollowed in all the experimental conditions; this response is applicable to "laser-drilling" of a hardened cement paste. (2) Evaluation of the kind of mortar for laser irradiation. Totally 75 laser irradiation tests for fixed mortar blocks were performed with combinations of following experimental conditions: fine aggregate in the mortar blocks was either of quartz, limestone, or Nachiguro-ishi. Although it was found that all kinds of the mortar fuse under laser irradiation after all, difference in the response to laser irradiation among the mortars was also found.

JAEA Reports

Research on removal technologies of fuel debris and in-vessel structures using laser light, 2; 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, 1; 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

Numerical simulation of laser processing

Yamada, Tomonori; Yamashita, Susumu; Sugihara, Kenta; Muramatsu, Toshiharu

Purazuma, Kaku Yugo Gakkai-Shi, 89(7), p.500 - 506, 2013/08

no abstracts in English

159 (Records 1-20 displayed on this page)