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Sumita, Takehiro; Sudo, Ayako; Takano, Masahide; Ikeda, Atsushi
Science and Technology of Advanced Materials; Methods (Internet), 2(1), p.50 - 54, 2022/02
Sanada, Yukihisa; Miyamoto, Kenji*; Ochi, Kotaro; Matsuzaki, Koji*; Ogawa, Toshihiro*; Senga, Yasuhiro*
Kaiyo Riko Gakkai-Shi, 24(2), p.9 - 18, 2018/12
Seven years passed since Fukushima Dai-ichi Nuclear Power Station accident which was caused large amount of radionuclide release to the sea. Elucidation of behavior mechanism of radiocesium in the seabed is required for restarting fishing industry. We developed radiation detection system using the unmanned surface vehicle for in-situ measurement of radiocesium concentration in seabed sediment. This system is able to automatically navigate to measurement point and obtain the radiation data on the bottom sediment. The detector was calibrated by comparing the actual sediment samples. The periodical measurement off-shore the Fukushima Prefecture was performed using developed this system. As these results, distribution of radiocesium concentration was changed due to oceanographic condition. However, radiocesium inventory was tendency to decrease according to radiocesium half-life in measurement area. This system is effective for elucidation of behavior mechanism of radiocesium because it can easily measure the radiocesium concentration in the bottom sediment.
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JAERI-M 82-191, 72 Pages, 1982/12
no abstracts in English
Hanawa, Satoshi; Hata, Kuniki; Uchida, Shunsuke; Nishiyama, Yutaka
no journal, ,
Water in the primary circuit of Nuclear Power Plants (NPPs) decomposes by radiolysis, then oxidants such as hydrogen peroxide and oxygen are generated as a result. Hydrogen peroxide is one of the major factor for initiation and propagation of stress corrosion cracking (SCC) in structural materials, hence in-situ monitoring of hydrogen peroxide at the point of interest in irradiation field is quite important to assure the integrity of NPPs. Concentration of hydrogen peroxide in irradiation field is governed by energy deposition by neutron and -ray in which the degree of energy is different in locations, while concentration in un-irradiation area decreases due to thermal decomposition. Quantitative evaluation of hydrogen peroxide is, however, available only by analyzing sampled water at present, and therefore in-situ monitoring of hydrogen peroxide at the point of interest becomes quite important. Frequency dependent complex impedance (FDCI) analysis gives characteristics of oxide film on the materials, and it becames clear by recent activities that the low frequency semicircles in Cole-Cole plots shows linear correlation to the concentration of hydrogen peroxide. JAEA is now developing a sensor for in-situ monitoring of hydrogen peroxide applicable to irradiation environment by applying FDCI. The outline and overall schedule of the sensor development will be reported in the presentation.