Sr Retardation Factor Experimental Study Of Loess

On the one hand, radionuclide is used for industry, which promotes the economic development; on the other hand, radionuclide is harmful to human health and ecological environment if it is not treated properly. Nowadays, the geologic disposal is considered as one of the best methods. And the superficial disposing is widely applied to treat the VLLW. Many factors need to be considered for choosing a suitable site to treat the radionuclide. And the migration of nuclide is one of the most important factors and must be considered.Firstly, we studied the behavior of Sr in contact with test loess through kinetic adsorption and the equilibrium was reached almost instantaneously. Then, adsorption isotherms of Sr on the test loess were studied using laboratory batch system and experimental concentration of Sr is rang from 5mg/l to 100mg/l. The adsorption isotherms of Sr were described by the Freundlich equation. The Kf value and 1/n value are 117.67 and 0.6791 respectively. And the Kd value is 55.01mL/g when the 1/n value is 1. The Kd values are all increased with the decreasing of temperature,the reducing of particle size,the increasing of initial concentration and the increasing of pH and have negative correlation of Ca2+ ion concentration.Secondly, the migration experiment lasted seven months about 215 days. The miscible displacement experiments were carried out on saturated homogeneous loess under steady-state flow at a specific pore water velocity to investigate the movement of Sr using bromide as a tracer. The vertical concentration distribution of Sr in column was obtained, which was used to compute the retardation coefficient. The results from leaching experiment suggested that maximum of concentration is located in 11.25cm. then the retardation coefficient was calculated and its value is 283.6.Finally,the computer code(HYDRUS-1D) was applied to fit the breakthrough curve of bromide. And by solving inverse problem of the convection dispersion equation, the relative parameters were obtained. Then the least-squares optimization approach was used to estimate the position of concentration of Sr in column.