Abstract

The purpose of the work is to analyze long-term radiocesium wash-off from the catchments contaminated due to the Chernobyl accident in 1986 and Fukushima Dai-ichi NPP (FDNPP) accident in 2011. A semiempirical diffusional model for radionuclide wash-off is proposed enabling estimation of ¹³⁷Cs dissolved and particulate wash-off coefficients for Chernobyl and Fukushima contaminated catchments, explaining the differences in these parameters and predicting their long-term trend. The model is based on the premise that the erosion of catchment topsoil is the source of sediments in the rivers, and the radionuclide concentration in the topsoil can be described by a simple diffusion equation. The normalized coefficients of particulate ¹³⁷Cs wash-off for the Fukushima contaminated catchments are slightly lower than those for Chernobyl. The normalized coefficients of the dissolved ¹³⁷Cs wash-off from Fukushima catchments are at least an order of magnitude lower those for Chernobyl, mainly due to an order of magnitude difference in the ¹³⁷Cs distribution coefficients for Fukushima and Chernobyl rivers. The proposed semiempirical diffusional model for radionuclide wash-off satisfactorily describes the temporal trends in the variations of the ¹³⁷Cs wash-off coefficients, both in the Chernobyl and Fukushima, and can be used for predicting ¹³⁷Cs wash-off after a nuclear accident.

中文翻译：

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受污染流域放射性核素冲刷的半经验扩散模型及其使用福岛河和切尔诺贝利河监测数据的测试

摘要

这项工作的目的是分析因 1986 年切尔诺贝利事故和 2011 年福岛第一核电站 (FDNPP) 事故而受到污染的集水区的长期放射性铯冲刷。提出了放射性核素冲刷的半经验扩散模型能够估计切尔诺贝利和福岛受污染集水区的¹³⁷ Cs 溶解和颗粒冲刷系数，解释这些参数的差异并预测它们的长期趋势。该模型的前提是流域表土的侵蚀是河流沉积物的来源，表土中的放射性核素浓度可以用简单的扩散方程来描述。颗粒物的归一化系数¹³⁷福岛受污染集水区的 Cs 冲刷量略低于切尔诺贝利。福岛集水区溶解的¹³⁷ Cs 冲刷的归一化系数至少比切尔诺贝利低一个数量级，主要是由于福岛河和切尔诺贝利河的¹³⁷ Cs 分配系数存在数量级差异。提出的放射性核素冲刷半经验扩散模型令人满意地描述了切尔诺贝利和福岛核事故中¹³⁷ Cs 冲刷系数变化的时间趋势，可用于预测核事故后的¹³⁷ Cs 冲刷。