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Sanada, Yukihisa; Abe, Tomohisa; Sasaki, Miyuki; Kanno, Marina*; Yamada, Tsutomu*; Nakasone, Takamasa*; Miyazaki, Nobuyuki*; Oshikiri, Keisuke*; Watabe, Hiroshi*
Journal of Nuclear Science and Technology, 10 Pages, 2023/00
The "treated water" from which the main radioactive materials were removed contains tritium, and stakeholders in Japan have been debating how to treat it. The amount of treated water stored in the facility has reached its limit, and the Japanese government has decided that the treatment method will be to discharge the water into the ocean by FY 2023 (FY: Fiscal Year). The present research developed a simple and practical tritium monitor for the Fukushima Daiichi Nuclear Power Station (FDNPS) tritiated water release. A simple and practical tritium monitor was developed for FDNPS tritiated water release based on thin plastic scintillator sheets. The developed devices were calibrated using standard tritium solutions and a method for calculating the minimum detectable activity. Fifteen 0.25 mm-thick scintillators can be placed in the 0.26 L flow cell where the sample water is fed, yielding an active surface area of 3,200 mm. The efficiency of tritiated water with full water is 0.000035 cps Bq. The minimum detectable activity under simple shielding conditions was 7,800 Bq L (Measurement time was 3,600 s).
Sanada, Yukihisa; Miyamoto, Kenji*; Momma, Hiroyasu*; Miyazaki, Nobuyuki*; Nakasone, Takamasa*; Tahara, Junichiro*; Baba, Shoichiro*; Furuyama, Hiroki*
Marine Technology Society Journal, 55(5), p.222 - 230, 2021/09
Large quantities of volatile radionuclides were released into the atmosphere following the Fukushima Daiichi Nuclear Power Station (FDNPS) accident in March 2011. To evaluate their effect on aquatic organisms and radiocesium behavior in the environment, the monitoring of radioactive cesium in the waterbed soil is important. We developed a dedicated radiation survey device that can both directly measure and collect some sediment samples. A comprehensive test was conducted using this device, which was installed in an unmanned surface vehicle at Fukushima offshore contaminated by radiocesium that resulted from the FDNPS accident. Consequently, the effectiveness of this device was confirmed because the measurement results of the sediment-core sample and in-situ radiation survey results show a good correlation. A successful application of this device in the time of post-nuclear facility accident is expected.
Ito, Chikara; Ito, Keisuke; Ishikawa, Takashi; Yoshida, Akihiro; Sanada, Yukihisa; Torii, Tatsuo; Notomi, Akihiro*; Wakabayashi, Genichiro*; Miyazaki, Nobuyuki*
Hoshasen, 39(1), p.7 - 11, 2013/09
no abstracts in English
Okuyama, Shinichi; Torii, Tatsuo; Suzuki, Akihiko*; Shibuya, Masanori*; Miyazaki, Nobuyuki*
Journal of Nuclear Science and Technology, 45(Suppl.5), p.414 - 416, 2008/06
Times Cited Count:27 Percentile:84.49(Nuclear Science & Technology)In case of a nuclear emergency when a large amount of radioactive substances and/or radiation is released from a nuclear facility, emergency radiation monitoring is carried out from the sea and air as well as from the ground adjacent to the facility to evaluate the influence of the radiation on the surrounding environment. As a means of radiation monitoring from the air, aerial monitoring using a manned helicopter is conducted. Although a manned helicopter can monitor a large area during a short time, flight at an altitude of 300 m or lower is prohibited by the Aviation Law in Japan. Therefore, it is difficult for a manned helicopter to measure the radiation profile near the ground and to measure the radiation level in a complicated terrain. In recent years, technologies for autonomous flying of industrial unmanned helicopters have been developed and applied to natural disasters. In expectation of the application of unmanned helicopters to aerial radiation monitoring during a nuclear emergency, we have developed a remote radiation monitoring system and investigated its possibilities.
Sanada, Yukihisa; Torii, Tatsuo; Miyazaki, Nobuyuki*
no journal, ,
no abstracts in English
Takamura, Yoshihide; Sanada, Yukihisa; Torii, Tatsuo; Miyazaki, Nobuyuki*
no journal, ,
no abstracts in English
Ito, Chikara; Yamamoto, Takahiro; Sekine, Takashi; Wakaida, Ikuo; Miyazaki, Nobuyuki*
no journal, ,
no abstracts in English
Sanada, Yukihisa; Sasaki, Miyuki; Miyazaki, Nobuyuki*; Torii, Tatsuo*
no journal, ,
Since the Fukushima Daiichi Nuclear Power Plant accident, various radiation imaging systems, including Compton cameras, have been developed. A fractal geometry-based detector (FRIE) has been developed as a detector that enables measurements in 360-degree directions, instead of the two-dimensional measurements of existing Compton cameras and pinhole-type cameras. In addition, by optimizing the inverse problem analysis method to match the characteristics of this detector, 3D radiation image reconstruction has been achieved. Here, as part of the series of presentations, we report the results of field tests in an environment using this detector system.