Study on Vertical Transfer of Radionuclide Co-60 in Broun Soil and Aeolian Sandy Soil Around Nuclear Power Plant

Abstract

The coastal soil surrounding to the Nuclear Power Plants were mainly classified to brown soil and aeolian sandy soil in China. In previous research, focused on the elements of Cs-137 and Sr-85 vertical transfer in these soils, but the Co-60, which was the most important factor in the brown soil and aeolian sandy soil were still urgent research. In this study, experiments were conducted to determine the vertical transfer of Co-60 in brown soil and aeolian sandy soil. The soil around Shidaowan Nuclear Power Plant were studied by using undisturbed soil column methods and isotope tracer technology, and identify the factors influencing their migration depths in soil. The results show that with the increase of leaching test, the migration of Co-60 in aeolian sandy soil was greater than that in brown soil, but the difference gradually decreases with the progress of spray test; the content of Co-60 in leaching water was very few and cannot be detected due to the strong adsorption by soil; after three years of undisturbed soil column experiment, 72.36 ∼ 85.26% of Co-60 mainly was retarded in the range of 0∼5cm in both of the soil surface. It was proved that Co-60 was difficult to migrate to groundwater in a short period. The distribution of specific activity of Co-60 in soil was an individual exponential declining with depth of oil. The results showed that the radionuclide Co-60 had little impact on groundwater in the years after the nuclear accident, but it should pay attention to the change of radioactivity concentration in surface soil and then select appropriate soil remediation methods. The study will provide a scientific basis for post-accident environmental impact assessment and post-accident soil remediation in China.