Saegusa Hiromitsu, Ohyama Takuya, Iijima Kazuki, Onoe Hironori, Takeuchi Ryuji, Hagiwara Hiroki
Fukushima Environmental Safety Center, Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Sahei Building, 1-29, Okitama-cho, Fukushima-shi, Fukushima 960-8034, Japan.
Fukushima Environmental Safety Center, Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Sahei Building, 1-29, Okitama-cho, Fukushima-shi, Fukushima 960-8034, Japan.
J Environ Radioact. 2016 Nov;164:36-46. doi: 10.1016/j.jenvrad.2016.04.020. Epub 2016 Jul 11.
The environment in the area around Fukushima Daiichi Nuclear Power Plant has been contaminated by widely deposited significant amount of radioactive materials, which were released to the atmosphere caused by the Fukushima Daiichi Nuclear Power Plant accident due to the Great East Japan Earthquake, which occurred on March 11, 2011. The radiocesium released in the accident mainly affects radiation dose in the environment. Decontamination work in the contaminated area except a mountain forests has been conducted to decrease the radiation dose. However, there are concerns that the redistribution of this radiation due to water discharge will occur due to the resulting transport of radiocesium. In particular, the deposition of soil particles containing radiocesium on the flood plains in the downstream areas of Fukushima's rivers can potentially increase the local radiation dose. Therefore, it is important to understand the influence of the deposition behavior of radiocesium on the radiation dose. Investigations of rivers have been performed to enhance the understanding of the mechanisms by which radiocesium is deposited on these flood plains. It was found that the spatial distribution of the radiocesium concentration on the flood plain along the river is heterogeneous with a dependence on the depositional condition and that the number of points with high air dose rates is limited. In detail, the radiocesium concentration and air dose rates in flood channels are higher than those at the edges of the river channels. Based on these heterogeneity and hydrological events, the deposition and transport mechanisms of the radiocesium due to water discharge at rivers were also interpreted, and a conceptual model was constructed.
福岛第一核电站周边地区的环境已被大量广泛沉积的放射性物质污染，这些物质是由于2011年3月11日发生的东日本大地震导致福岛第一核电站事故释放到大气中的。事故中释放的放射性铯主要影响环境中的辐射剂量。为降低辐射剂量，已对除山林之外的污染区域开展了去污工作。然而，人们担心由于放射性铯的迁移，排水会导致这种辐射重新分布。特别是，含有放射性铯的土壤颗粒在福岛河流下游地区的洪泛平原上沉积，可能会增加当地的辐射剂量。因此，了解放射性铯的沉积行为对辐射剂量的影响非常重要。已对河流进行了调查，以加深对放射性铯在这些洪泛平原上沉积机制的理解。研究发现，沿河流洪泛平原上放射性铯浓度的空间分布是不均匀的，取决于沉积条件，且高空气剂量率点的数量有限。具体而言，洪水河道中的放射性铯浓度和空气剂量率高于河道边缘。基于这些不均匀性和水文事件，还对河流排水导致放射性铯的沉积和迁移机制进行了解释，并构建了一个概念模型。
