Vertical distribution of 90 Sr and 137 Cs in soils near the Fukushima Daiichi nuclear power station
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Vertical distribution of 90Sr and 137Cs in soils near the Fukushima Daiichi nuclear power station Takayuki Sasaki1 · Daisuke Matoba1 · Terumi Dohi2 · Kenso Fujiwara2 · Taishi Kobayashi1 · Kazuki Iijima2 Received: 9 April 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract The radioactivity concentrations for 90Sr and 137Cs in soil samples collected near Fukushima Daiichi nuclear power station were investigated. The depth profile of 137Cs from the surface soil to 20 cm showed a typical decreasing tendency, that is, high radioactivity from the surface down to 5 cm due to the strong sorption of specific minerals. After deposition of 90Sr, 90 Sr has migrated to deeper soil layers in the past 5 years compared to 137Cs. This tendency was supported by the results of sequential extraction to identify the predominant sorption species, and by the sorption coefficients determined by batch-wise sorption experiments. Keywords 90Sr · 137Cs · Soil · Depth profile · Fukushima Daiichi nuclear power station
Introduction The severe accident at Fukushima Daiichi nuclear power station (FDNPS) on 11 March 2011 was caused by the tsunami that followed the great earthquake of magnitude 9.0. Hydrogen explosions, a breach of reactor pressure vessels, and vent operations occurred in reactors, resulting in the release into the atmosphere of enormous amounts of radionuclides contained within the fuel. Highly radioactive plumes, containing fission products such as 134Cs, 135Cs, 137Cs, 131I, 129mTe, and 90 Sr, were transported from the reactor buildings to the local and regional environment [1–3]. Several years after the accident, many researchers have been involved in tracking and monitoring hazardous radionuclides, especially the gamma emitter 137Cs with a half-life of ca. 30 years [4]. Both wet and dry deposits of radioactive Cs have been investigated [5, 6]. Sanada et al. [7] measured the distribution of air dose Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10967-020-07294-3) contains supplementary material, which is available to authorized users. * Takayuki Sasaki sasaki.takayuki.2a@kyoto‑u.ac.jp 1
Department of Nuclear Engineering, Kyoto University, Kyoto‑daigaku‑Katsura, Nishikyo, Kyoto 615‑8540, Japan
Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Miharu‑machi, Fukushima 963‑7700, Japan
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rates and the distribution of radioactive cesium deposition on the ground within a radius of approximately 5 km from the NPS, using an air-borne survey system. The footprint of several radioactive plumes with quite high gamma radioactivity that extended from the FDNPS was illustrated. Meanwhile, less emission of Sr has been estimated and this attributed to its lower volatility. In a report by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) [8], it is noted that a short half-life radionuclide (89Sr), which is a characteristic product of nuclear accidents, was detected in 5 cm-thick soil from the surface collected from a wide area of Fukus
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