The migration experiment of Sr-90 in variable saturated soils and numerical simulation used Hydrus-3d

There is a scientific support that migration data of Sr-90 in the nuclear waste landfill soil will provide for safety estimation and accident response measures in landfill.In order to make a more accurate prediction of the migration of Sr-90, it is critical to get the migration parameters such as longitudinal (or transverse) dispersivity and partition coefficient. This article try to use a method for estimating the migration parameters of Sr-90 in variable saturated soils combining experiment and numerical simulation, then explores the method with the migration of Sr-90 in silty loam in Shanxi province as an example. The migration experiment of Sr-90 was carried by column method , the water flow in is 375 mL/d, the pH value was about 7 at room temperature. The results show that the migration distance of central flow direction for Sr-90 is 3.9 cm and the peak concentration is 1.04×104 Bq/cm3. According to the concentration distribution of Sr-90 in the soil column combined with three-dimensional numerical model of nuclide migration (Hydrus-3d), the partition coefficient in the silty loam is 79 ml/g while the longitudinal dispersivity is 0.7 cm and the transverse dispersivity is 0.8 cm by fitting. This method takes the porosity and water velocity of solid into consideration that static experiments fail to cover and obtains the longitudinal and transverse dispersivity at the same time, which making the results more tally with the actual situation.