Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan.
Institute for Integrated Radiation and Nuclear Science, Kyoto University, Osaka, Japan; Egypt Second Research Reactor, Egyptian Atomic Energy Authority, Cairo, Egypt.
J Environ Radioact. 2020 Nov;223-224:106388. doi: 10.1016/j.jenvrad.2020.106388. Epub 2020 Aug 29.
Radioactive caesium was released during the accident of Fukushima Dai-ichi nuclear power plant (FDNPP) into the surrounding environment. In the current work, radiocaesium micro-particles (CsMPs) and radiocaesium-rich soil particles were selectively separated from soil particles as well as from each other using autoradiography-based procedure. The applied separation scheme is based on water dilution followed by drying of the soil sample prior to imaging plate autoradiography. The SEM/EDS investigation of the individual CsMPs showed that these particles have a silicate glass structure and vary in shape with a diameter less than 10 μm. For the first time, a two-stage formation mechanism was suggested for a CsMP based on shape and structure heterogeneity of its two parts. Perfect spherical core might be formed in the first stage with a remarkable lower content of Al, and relatively higher concentrations of Si and K than an outer angulated structure, which might be attached to the core sphere during a late stage. The radiocaesium-rich soil particles have bigger size than CsMPs and have a plate-like structure with cleavages inside the grains, which suggest that these particles might be a weathered biotite. The average radioactivity ratio of Cs/Cs (dated March 11, 2011) in the investigated particles was found to be 1.05 ± 0.01, which confirmed that the radiocaesium in CsMPs and in the contaminated soil particles has the same source of origin, which could be unite 3 of FDNPP.
福岛第一核电站（FDNPP）事故期间，放射性铯释放到周围环境中。在当前的工作中，使用基于放射性自显影的程序，从土壤颗粒以及彼此之间选择性地分离放射性铯微颗粒（CsMPs）和富含放射性铯的土壤颗粒。所应用的分离方案基于水稀释，然后在成像板放射性自显影之前干燥土壤样品。对单个 CsMPs 的 SEM/EDS 研究表明，这些颗粒具有硅酸盐玻璃结构，形状各异，直径小于 10μm。首次提出了基于 CsMP 形状和结构异质性的两阶段形成机制。第一阶段可能形成完美的球形核心，其 Al 含量显著降低，Si 和 K 的浓度相对较高，而外部棱角结构可能在后期附着在核心球体上。富含放射性铯的土壤颗粒比 CsMPs 更大，具有板状结构，颗粒内部有劈裂，表明这些颗粒可能是风化的黑云母。在所研究的颗粒中，Cs/Cs（2011 年 3 月 11 日测定）的平均放射性比为 1.05±0.01，这证实了 CsMPs 和污染土壤颗粒中的放射性铯具有相同的起源，可能来自 FDNPP 的 3 号机组。
