核电厂周边土壤中放射性核素60Co的淋溶迁移分布

 我国核电厂址目前主要以滨海厂址为主，周边土壤多为棕壤土和风砂土，关于核素¹³⁷Cs和⁸⁹Sr等核素在土壤中迁移分析较多，关于⁶⁰Co在棕壤土和风砂土中的迁移报道较少。本研究采用原状土柱法及同位素示踪技术，采集我国三代核电“国和一号”石岛湾示范厂址周边的原状土柱，开展放射性核素⁶⁰Co在棕壤土和风砂土中的淋溶垂直迁移实验，模拟核事故后放射性核素⁶⁰Co在2种土壤中的垂直迁移，分析影响⁶⁰Co垂直迁移的相关因素，预测核事故后⁶⁰Co对地下水的影响。实验结果表明，随着淋溶实验的增加，风砂土中⁶⁰Co迁移量比棕壤土中的大，但随着喷淋实验的进行差异渐趋减小；由于土壤对⁶⁰Co的极强吸附，导致淋溶水检测不到⁶⁰Co；经过为期3年的原状土柱实验，72.36%~85.26%的⁶⁰Co主要滞留于土壤表层0~5 cm范围内，因此⁶⁰Co短期内很难迁移到地下水中。土壤中⁶⁰Co比活度与距离土壤表层深度分布呈单项指数规律。

Leaching and vertical transfer of radionuclide 60Co in soils around Nuclear Power Plant

The soils surrounding coastal nuclear power plant are currently mainly brown soil and aeolian sandy soil in China . Previous research focused on the characteristics of ¹³⁷Cs and ⁸⁹Sr in different soils, and details of ⁶⁰Co in brown soil and aeolian sandy soil are still inadequate. This study deals with an experiment to determine the vertical migration of ⁶⁰Co in brown soil and aeolian sandy soil. The soils around Shidaowan Nuclear Power Plant are studied by using undisturbed soil column methods and isotope tracer technology to identify the factors influencing the migration depths in soil. The results show that with the increase of the number of leaching tests the migration of ⁶⁰Co in aeolian sand soil is greater than that in brown soil, but the difference gradually decreases with the progress of spray test; that the content of ⁶⁰Co in leaching water is very little and cannot be detected due to the strong adsorption by soil; and that after three years of undisturbed soil column experiment, 72.36~85.26% of ⁶⁰Co mainly is retarded in the range of 0~5 cm in both soil surfaces. It is proved that ⁶⁰Co is difficult to migrate to groundwater in a short period. The distribution of specific activity of ⁶⁰Co in soil is an individual exponential declining with the depth of oil. The study provides technical support for post-accident environmental impact assessment and post-accident soil treatment in future.