Abstract:Based on the dynamic soil column method in laboratory, experiment was conducted on studying the migration of radionuclide Sr-90 in Sand relative to different spraying intensity(spraying intensity was designed to 120 ml d-1, 60 ml d-1, 30 ml d-1,and the corresponding experimental time were 51, 102 204 day respectively).Results showed that migration distance of Sr-90 concentration peak in the soil columns more or less the same, were 42.3 cm、46.2 cm、44.4 cm, Which was positively related to intensity and duration of the spraying. In addition, the concentration distribution curves of Sr-90 in soil column section all exhibited asymmetry and “tailing” phenomena under the three different spray intensity, i.e. After Sr-90 was leached down from the source layer, it was adsorbed to the Sand, thus lagging behind and getting desorbed after the peak concentration passing the observation point, hence Sr-90 concentration remained to be quite high in soil columns for a long time. With the aid of HYDRUS-1D software, two numerical models were established for radionuclide migration, one based on equilibrium adsorption and the other on non-equilibrium adsorption. It was found that the non-equilibrium sorption model, which took into account the first-order rate coefficients β, could be used to better explain the asymmetry and tailing phenomena. Based on fitting the measurements of Sr-90 concentrations in the soil columns, distribution coefficient of Sr-90 in the Sand was figured out to be 0.73 ml g-1, 0.70 ml g-1 and 0.72 ml g-1 relative to intensity of the spraying, which shows that intensity of the spraying did not have much effect on distribution coefficient of Sr-90.