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Furusawa, Akinori; Nishimura, Akihiko; Takenaka, Yusuke*
no journal, ,
Large number of concrete structures built in the era of rapid economic growth will exceed fifteen years old in next 10 to 20 years. Developing maintenance and health monitoring techniques for these existing concrete structures is inevitable problem to be resolved. JAEA have tackled to that problem on collaborative research, having achieved to crack detection technique for surface on the concrete of railroad tunnel (1). The technique reported in ref. (1), however, is focusing on the surface cracks, not taking into account the condition of the deep region, including a steel reinforcing bar (rebar) in a reinforced concrete structure. This work supposes a new approach for detecting deteriorated rebar in concrete structure based on laser-ultrasonic. Irradiating the one end of a rebar by nanosecond laser pulses repetitively generates ultrasonic wave propagating along it. The waveform of the ultrasonic received the other end is analyzed to extract the information about its condition.
Yamada, Tomonori; Nguyen, P. L.; Hanari, Toshihide; Shibata, Takuya; Nishimura, Akihiko; Koyama, Shinichi; Daido, Hiroyuki; Shimada, Yoshinori*; Kotyaev, O.*; Kurahashi, Shinri*
no journal, ,
For decommissioning of the Fukushima Daiichi Nuclear Power Station (NPS) of Tokyo Electric Power Company, Incorporated, it is essential to dispose radioactive wastes resulted from the accident. The wastes cannot be diagnosed and removed manually on account of exposure to high radiation dose. Thus research and development of remote techniques for wastes is indispensable. In terms of remote handling, a fiber delivered laser beam can access into the narrow gap and process the object without repulsive force. That is a powerful advantage of laser processing. We are now developing remote laser techniques for sensing and sampling at the Naraha Remote Technology Development Center.
Ueda, Masashi; Saruta, Koichi; Yamaguchi, Toshihiko
no journal, ,
Nishimura, Akihiko; Shibata, Takuya; Yamada, Tomonori; Suzuki, Hiroshi*; Shimada, Kozue; Sato, Yuki; Torii, Tatsuo; Koyama, Shinichi
no journal, ,
In August 2015, we ran an educational program about laser technologies in Tsuruga district of Fukui prefecture and did the other about robot technologies in Tokai of Ibaraki separately. After the establishment of the Naraha remote Technology Development Center, a more advanced educational program was arranged in September 2016. It was a 10 days internship program where we focused the sensing techniques with robotic technologies. We are fighting the problems to break through the present miserable situation of Fukushima Daiichi NPPS. Countermeasure technique against water leakage for the suppression chamber is most needed. As a means of eventually sealing down, UV activating polymerization is under testing. Remote sensing for the pedestal concrete strength is also indispensable. Laser ablation technique for ICP-MS is now under preparation. And the facility has been opened for user's R&D at a low price.
Oka, Kiyoshi*; Nishimura, Akihiko
no journal, ,
no abstracts in English