Institute for Radiological Protection and Nuclear Safety (IRSN), Environmental Research Division, BP 3-13115 St-Paul-lez-Durance Cedex, France.
Environ Sci Technol. 2014 Oct 7;48(19):11268-76. doi: 10.1021/es502590s. Epub 2014 Sep 22.
The Fukushima Dai-ichi nuclear accident led to massive atmospheric deposition of radioactive substances onto the land surfaces. The spatial distribution of deposits has been estimated by Japanese authorities for gamma-emitting radionuclides through either airborne monitoring surveys (since April 2011) or in situ gamma-ray spectrometry of bare soil areas (since summer 2011). We demonstrate that significant differences exist between the two surveys for radiocaesium isotopes and that these differences can be related to dry deposits through the use of physically based relationships involving aerosol deposition velocities. The methodology, which has been applied to cesium-134 and cesium-137 deposits within 80-km of the nuclear site, provides reasonable spatial estimations of dry and wet deposits that are discussed and compared to atmospheric numerical simulations from the Japanese Atomic Energy Agency and the French Institute of Radioprotection and Nuclear Safety. As a complementary approach to numerical simulations, this field-based analysis has the possibility to contribute information that can be applied to the understanding and assessment of dose impacts to human populations and the environment around Fukushima.
福岛第一核电站核事故导致大量放射性物质通过大气沉降作用沉积在陆地表面。日本当局通过航空监测调查（自 2011 年 4 月起）或对裸露土壤地区进行现场伽马射线光谱测量（自 2011 年夏季起），对释放出的γ放射性核素的沉积情况进行了估计。我们证明，两种调查方法在放射性铯同位素方面存在显著差异，并且可以通过使用涉及气溶胶沉积速度的物理关系，将这些差异与干沉积联系起来。该方法已应用于距离核设施 80 公里范围内的铯-134 和铯-137 沉积物，为干湿沉积提供了合理的空间估算，并与日本原子力安全保安院和法国放射防护与核安全研究所的大气数值模拟结果进行了讨论和比较。作为对数值模拟的补充方法，这种基于现场的分析有可能提供可用于了解和评估福岛周边人类群体和环境所受剂量影响的信息。
