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Journal Articles

A Study of cladding technology on tube wall surface by a hand-held laser torch

Terada, Takaya; Nishimura, Akihiko; Oka, Kiyoshi; Moriyama, Taku*; Matsuda, Hiroyasu*

Hozengaku, 13(4), p.87 - 94, 2015/01

Journal Articles

Demonstration of heat resistant fiber Bragg grating sensors based on femtosecond laser processing for vibration monitoring and temperature change

Nishimura, Akihiko; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya; Terada, Takaya; Daido, Hiroyuki

Journal of Laser Micro/Nanoengineering, 9(3), p.221 - 224, 2014/11

 Times Cited Count:0 Percentile:100(Nanoscience & Nanotechnology)

Heat resistant FBG sensors were developed by femtosecond laser processing to apply them to high temperature operated piping system of nuclear power plants. The FBG sensor was installed on the surface of a steel blade and a vibration test was conducted to detect the resonant vibration frequency of the vibrating blade. The FBG sensor had the heatproof performance at 600$$^{circ}$$C. A frequency stabilized sensing system using a tunable laser was tested for structural health monitoring in daily operation of nuclear power plants. The FBG sensor was installed on the surface of a steel blade for vibration induced strain measurements. Welding, brazing, soldering and noble metal powder adhesive were discussed for molding the FBG sensors.

Journal Articles

New instrumentation using a heat resistant FBG sensor installed by laser cladding

Nishimura, Akihiko; Terada, Takaya; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya

Proceedings of 22nd International Conference on Nuclear Engineering (ICONE-22) (DVD-ROM), 6 Pages, 2014/07

Since 2007, JAEA has been developing laser based technologies of structural health monitoring. The FBG sensor made by femtosecond laser processing will be the best candidate. To make the best use of the heat resistant characteristic, the FBG sensor was embedded in metal mold by laser cladding. A groove was processed to the surface of a SUS metal plate. We used a QCW laser to weld a filler wire on the plate. A series of weld beads perfectly formed a sealing clad on the groove. Though the FBG sensor was buried tightly, no degradation on the reflection spectrum was detected after the processing. The FBG sensor could detect the vibration of the plate caused by impact shocks and audio vibration. The reflection peak of the FBG sensor under laser cladding condition was shifted to be 6 nm. We demonstrated that the corresponded temperature derive from the reflection peak shift reached 600 degrees in heat shock experiments. The installation procedure of a FBG sensor using a portable laser cladding machine was described.

Journal Articles

Demonstration of heat resistant Bragg grating by femtosecond laser processing for vibration monitoring

Nishimura, Akihiko; Takenaka, Yusuke*; Furuyama, Takehiro*; Shimomura, Takuya; Terada, Takaya; Daido, Hiroyuki

Proceedings of 1st Smart Laser Processing Conference 2014 (SLPC 2014), 4 Pages, 2014/04

Heat resistant FBG sensors were developed by femtosecond laser processing. In order to apply them to piping system of nuclear power plants, vibration test under high temperature was demonstrated. The FBG sensor had the heatproof performance at 600$$^{circ}$$C. A frequency stabilized sensing system using a tunable laser was tested for structural health monitoring in daily operation of nuclear power plants. The FBG sensor was installed on the surface of a steel blade for vibration induced strain measurements. Welding, brazing, soldering and noble metal powder adhesive were discussed for molding the FBG sensors.

Journal Articles

Characteristics of the heat resistant FBG sensor under laser cladding condition

Nishimura, Akihiko; Terada, Takaya

Proceedings of SPIE, Vol.8963 (CD-ROM), p.896307_1 - 896307_7, 2014/02

 Times Cited Count:0 Percentile:100

We proposed FBG sensor made by femtosecond laser processing could be the best candidate. Combination with fabric reinforcement and heatproof adhesive mold protected fragile optical fiber. To make the best use, we fixed the FBG sensor by metal mold. A groove was processed to a SUS metal plate with a grindstone. We used a Quasi-CW laser to weld a filler wire on plate. The optical fiber set under the filler wire beforehand was heated by the laser pluses with 10 J and 10 ms, partially to be soaked in a weld pool. A series of weld pool formed a sealing clad on the groove. The FBG sensor was buried at 2 mm depth over the length of 1 cm. No degradation on its reflection spectra was detected before and after the processing. The FBG sensor can detect the vibration of the plate caused by impact shocks. In this paper, Bragg peak shift of the FBG sensor under laser cladding condition has been discussed.

Journal Articles

Instrumentation device and surface control technology for coolant piping system of nuclear power plants

Nishimura, Akihiko; Terada, Takaya; Shimada, Yukihiro; Yonemoto, Yukihiro*; Yamada, Tomonori

Proceedings of 20th International Conference on Nuclear Engineering and the ASME 2012 Power Conference (ICONE-20 & POWER 2012) (DVD-ROM), 5 Pages, 2012/07

Instrumentation devices using laser technologies were developed for maintenance of coolant piping system. For instrumentation devices, seismic monitoring by optical fiber sensors was able to detect vibration of piping system. X-ray absorption contrast by synchrotron radiation clarified convection motion inside a molten pool produced by laser welding. For surface control technologies, a new probing system was under development for heat exchanger tubes by laser cladding. And laser ablation could be used for surface cleaning. These technologies are expected for maintenance of the piping system of nuclear power plants.

Journal Articles

Development of worldwide version of system for prediction of environmental emergency dose information; WSPEEDI 2nd version

Terada, Hiroaki; Nagai, Haruyasu; Furuno, Akiko; Kakefuda, Toyokazu; Harayama, Takaya*; Chino, Masamichi

Nippon Genshiryoku Gakkai Wabun Rombunshi, 7(3), p.257 - 267, 2008/09

The second version of WSPEEDI (WSPEEDI-II) which has functions to predict the radiological impact of nuclear accident abroad on Japan by quick calculations of air concentration, surface deposition and radiological doses is developed. WSPEEDI-II has the following functions for practical use. (1) High performance prediction of atmospheric dispersion of radionuclides from local to regional ranges with appropriate resolutions by introducing non-hydrostatic atmospheric dynamic model. (2) Source term estimation by coupling calculation results and monitoring data for the case that no source information is available from abroad. (3) On-line prediction data exchanges with major emergency response systems in the United States and Europe with the similar functions as WSPEEDI-II. (4) Web-based graphical user interface system for easy operation of WSPEEDI-II. (5) Preset East-Asian database for the quick start against a nuclear accident in Eastern Asia. This paper describes these new functions.

JAEA Reports

Numerical simulation system for environmental studies: SPEEDI-MP

Nagai, Haruyasu; Chino, Masamichi; Terada, Hiroaki; Harayama, Takaya*; Kobayashi, Takuya; Tsuzuki, Katsunori; Kim, K.; Furuno, Akiko

JAEA-Research 2006-057, 67 Pages, 2006/09

JAEA-Research-2006-057.pdf:13.49MB

A numerical simulation system SPEEDI-MP has been developed to apply for various environmental studies. SPEEDI-MP consists of dynamical models and material transport models for the atmospheric, terrestrial, and oceanic environments, database for model inputs, and system utilities for file management, visualization, etc. As a numerical simulation tool, a model coupling program (model coupler) has been developed. A coupled model system for water circulation has been constructed with atmosphere, ocean, wave, hydrology, and land-surface models using the model coupler. System utility GUIs are based on the Web technology, allowing users to manipulate all the functions on the system using their own PCs via the internet. In this system, the source estimation function in the atmospheric transport model can be executed on the grid computer system. Performance tests of the coupled model system for water circulation were also carried out for the flood and the storm surge events.

Journal Articles

Production processes of H(D) atoms in the reactions of NO(A$$^{2}Sigma^{+}$$) with C$$_{2}$$H$$_{2}$$, C$$_{2}$$H$$_{4}$$, H$$_{2}$$O and their isotopic variants

Umemoto, Hironobu*; Terada, Naoki*; Tanaka, Kunikazu*; Takayanagi, Toshiyuki; Kurosaki, Yuzuru; Yokoyama, Keiichi

Chemical Physics, 259(1), p.39 - 47, 2000/09

 Times Cited Count:7 Percentile:77.46

no abstracts in English

Oral presentation

Development of fundamental technology for laser cladding in heat exchanger tube

Terada, Takaya; Yamada, Tomonori; Nishimura, Akihiko

no journal, , 

no abstracts in English

Oral presentation

Development of laser cladding technology for maintenance of pipe wall thinning

Terada, Takaya; Nishimura, Akihiko; Oka, Kiyoshi

no journal, , 

no abstracts in English

Oral presentation

Development of inspection technology for laser welding section

Nishimura, Akihiko; Terada, Takaya; Yamada, Tomonori; Takenaka, Yusuke*; Furuyama, Takehiro*

no journal, , 

We are developing the inspection technology for laser micro spot welding. Butt welding for the inner wall of heat exchanger tubes were successfully carried out by a composite-type optical fiber scope. The related technologies are the following: (1) Rapid inspection by eddy current testing (2) Fiber endoscope observation (3) Synchrotron X-ray absorption contrast method. These technologies are versatile to be applied in maintenance for industrial production plants.

Oral presentation

Development of laser cladding and in-situ observation technology in heat exchanger tubes

Terada, Takaya; Nishimura, Akihiko; Oka, Kiyoshi

no journal, , 

no abstracts in English

Oral presentation

Development of laser cladding devices for maintenance of heat exchanger tube

Terada, Takaya; Nishimura, Akihiko

no journal, , 

no abstracts in English

Oral presentation

Remote processing technology of solid surface by pulse laser

Yonemoto, Yukihiro; Nishimura, Akihiko; Shimada, Yukihiro; Terada, Takaya

no journal, , 

no abstracts in English

Oral presentation

Development of new probing system with LIBS and fiber scope inspection for damaged nuclear reactor core

Nishimura, Akihiko; Ito, Fuyumi; Terada, Takaya; Shimada, Yukihiro

no journal, , 

no abstracts in English

Oral presentation

Development of narrow space laser cladding system

Terada, Takaya; Nishimura, Akihiko

no journal, , 

no abstracts in English

Oral presentation

Development of inspection repair technology for tube inner wall of aging nuclear power plants

Ito, Fuyumi; Nishimura, Akihiko; Yonemoto, Yukihiro*; Terada, Takaya; Shimada, Yukihiro

no journal, , 

Development of inspection repair technology for tube inner wall of aging nuclear power plants was described. Three functions of the pulse laser, observation by the composite-type optical fiber scope, and laser-induced breakdown spectroscopy (LIBS) are built into a coupling device. In addition, to facilitate the observation of the cracks, we adopted the magnetic particle testing (MT). And to remove the dispersed magnetic particle liquid from cracks after MT, we manufactured a microcapsule containing the magnetic particle liquid. Furthermore, pulse laser ablation with LIBS can clean up the oxide layer of the inner wall of heat exchanger tubes. Applying LIBS on tube inner wall before MT can give us the information about cracks and defects.

Oral presentation

Observation of laser cladding process by synchrotron radiation X-ray

Terada, Takaya; Yamada, Tomonori; Shobu, Takahisa; Nishimura, Akihiko

no journal, , 

no abstracts in English

Oral presentation

Combination of LIBS and fiber endoscopic observation in limited tubular space

Nishimura, Akihiko; Ito, Fuyumi; Terada, Takaya; Tomiyoshi, Kentaro; Oka, Kiyoshi

no journal, , 

no abstracts in English

40 (Records 1-20 displayed on this page)