会議発表用資料 Sr-90 measurement in Japanese soil samples after the Fukushima nuclear accident

Sahoo, S.K.  ,  Kavasi, N.  ,  Mietelski, J.W.  ,  Sorimachi, A.  ,  Lokas, E.  ,  Aono, T.

2015-09-21
内容記述
The cooling system of the nuclear reactors were damaged by a devastating tsunami hitting the Fukushima Daiichi Nuclear Power Plant (FDNPP), Japan, which resulted in a nuclear major accident (Level 7 of the International Nuclear and Radiological Event Scale) with international radioactive contamination. Among the released volatile fission products (I, Te, Cs isotopes), intermediate volatile elements such as Sr and Ru isotopes also were emitted.Sr-90 is a biologically hazardous radionuclide considering its similar metabolism in human tissues to the calcium. Bone cells can uptake strontium from the blood and recreate the bone tissue wherein the decaying Sr-90 and its decay product Y-90 can cause internal radiation exposure. Therefore, the environmental monitoring to reveal the contaminated areas in Japan is essential.In this study, soil samples with relatively high Cs-137 were collected from the vicinity of the damaged Fukushima Daiichi Nuclear Power Plant. The soil samples were chemically open digested using an acid mixture of HNO3, HF and HClO4. The strontium separation was carried out using extraction chromatography resin (Sr resin) and Sr-90 was detected with a liquid scintillation counter system (TriCarb-3100).The level of activity concentrations of Sr-90 in the analysed soil samples was no more than tens of Bq kg-1 showing good agreement with the results of recently published surveys (Kavasi, 2015, Mishra, 2014). It has been reported in Japan before the FDNPP about radioactive background contamination of Sr-90 about 6 Bq m-2 in soil might be originated from atmospheric nuclear weapon tests. In this study, we did not notice any significant Sr-90 contamination from the limited samples and internal radiation dose caused by Sr-90 uptake could be negligible.AcknowledgmentsThis work was partially funded by Fukushima Prefecture related to Research and Development in Radiological Sciences.ReferencesKavasi, N., Sahoo, S. K., Sorimachi, A., Tokonami, S., Aono, T and Yoshida, S. (2015) J. Radioanal. Nucl. Chem. 303, 2565-2570Mishra, S., Sahoo S. K., Arae, H., Watanabe Y and Mietelski J. W. (2014) J. Chromatogr. Sep. Tech. 5:6, 1000250.
International Conference Enviromental Radioactivity

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