Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant.
Caesium-rich micro-particles: A window into the meltdown events at the Fukushima Daiichi Nuclear Power Plant.
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DOI：
10.1038/srep42731
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发表时间：
2017-02-15
影响因子：
4.6
通讯作者：
Utsunomiya S
中科院分区：
文献类型：
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作者：
Furuki G;Imoto J;Ochiai A;Yamasaki S;Nanba K;Ohnuki T;Grambow B;Ewing RC;Utsunomiya S
2011年3月发生在福岛第一核电站（FDNPP）的核灾难导致三个反应堆部分熔毁。在熔毁过程中，一种浓缩粒子，一种富铯微粒（CsMP），通过未知的过程在反应堆内部形成。本文报道了基于原子分辨电子显微镜在FDNPP附近发现的CsMP的熔毁过程中反应堆内部CsMP形成的化学和物理过程。所有CsMPs（尺寸为2.0-3.4 μm）由SiO2玻璃基体和~10纳米尺寸的Zn-Fe-oxide纳米颗粒组成，并伴有广泛的Cs浓度（Cs为Cs2O的1.1-19 wt%）。微量的铀也与锌铁氧化物有关。CsMPs中的纳米结构记录了严重FDNPP事故中熔毁过程中的多个反应过程步骤：熔化的燃料（熔芯）-混凝土相互作用（MCCIs），结合各种空气裂变产物纳米粒子，包括CsOH和CsCl，通过SiO2凝结在源自反应堆压力容器失效的锌-铁氧化物纳米粒子聚集体上进行。尽管如此，CsMPs提供了一种挥发性和低挥发性放射性核素（如U）可以到达环境的机制，应该在FDNPP周围当前环境中Cs和放射性核素的迁移模型中加以考虑。
The nuclear disaster at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in March 2011 caused partial meltdowns of three reactors. During the meltdowns, a type of condensed particle, a caesium-rich micro-particle (CsMP), formed inside the reactors via unknown processes. Here we report the chemical and physical processes of CsMP formation inside the reactors during the meltdowns based on atomic-resolution electron microscopy of CsMPs discovered near the FDNPP. All of the CsMPs (with sizes of 2.0–3.4 μm) comprise SiO2 glass matrices and ~10-nm-sized Zn–Fe-oxide nanoparticles associated with a wide range of Cs concentrations (1.1–19 wt% Cs as Cs2O). Trace amounts of U are also associated with the Zn–Fe oxides. The nano-texture in the CsMPs records multiple reaction-process steps during meltdown in the severe FDNPP accident: Melted fuel (molten core)-concrete interactions (MCCIs), incorporating various airborne fission product nanoparticles, including CsOH and CsCl, proceeded via SiO2 condensation over aggregates of Zn-Fe oxide nanoparticles originating from the failure of the reactor pressure vessels. Still, CsMPs provide a mechanism by which volatile and low-volatility radionuclides such as U can reach the environment and should be considered in the migration model of Cs and radionuclides in the current environment surrounding the FDNPP.