Onda Yuichi, Kato Hiroaki, Hoshi Masaharu, Takahashi Yoshio, Nguyen Minh-Long
Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
J Environ Radioact. 2015 Jan;139:300-307. doi: 10.1016/j.jenvrad.2014.06.002. Epub 2014 Jun 22.
The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident resulted in extensive radioactive contamination of the environment via deposited radionuclides such as radiocesium and (131)I. Evaluating the extent and level of environmental contamination is critical to protecting citizens in affected areas and to planning decontamination efforts. However, a standardized soil sampling protocol is needed in such emergencies to facilitate the collection of large, tractable samples for measuring gamma-emitting radionuclides. In this study, we developed an emergency soil sampling protocol based on preliminary sampling from the FDNPP accident-affected area. We also present the results of a preliminary experiment aimed to evaluate the influence of various procedures (e.g., mixing, number of samples) on measured radioactivity. Results show that sample mixing strongly affects measured radioactivity in soil samples. Furthermore, for homogenization, shaking the plastic sample container at least 150 times or disaggregating soil by hand-rolling in a disposable plastic bag is required. Finally, we determined that five soil samples within a 3 m × 3-m area are the minimum number required for reducing measurement uncertainty in the emergency soil sampling protocol proposed here.
福岛第一核电站事故通过放射性铯和碘-131等沉降放射性核素导致了环境的广泛放射性污染。评估环境污染的程度和水平对于保护受影响地区的居民以及规划去污工作至关重要。然而，在这种紧急情况下需要一个标准化的土壤采样方案，以便于采集大量易于处理的样本用于测量伽马发射放射性核素。在本研究中，我们基于对福岛第一核电站事故影响区域的初步采样制定了一个紧急土壤采样方案。我们还展示了一项初步实验的结果，该实验旨在评估各种操作程序（如混合、样本数量）对测量放射性的影响。结果表明，样本混合对土壤样本中测量的放射性有强烈影响。此外，为了实现均匀化，需要将塑料样本容器摇晃至少150次，或者在一次性塑料袋中手工滚动土壤使其分散。最后，我们确定在3米×3米的区域内采集五个土壤样本是在此提出的紧急土壤采样方案中减少测量不确定性所需的最少样本数量。
