Modeling migration of strontium in sand and gravel aquifer in the candidate VLLW disposal site

摘要

For the very low level radioactive waste (VLLW) disposal site, it is essential to study the regional hydrogeological condition and the transportation process of nuclide in the disposal site with the engineering barrier. The candidate VLLW repository located at the confluence of two rivers in the southwest of China, which included the characters of enrichment of the rainfall, closing to the river and inhomogeneous media. Several key aspects were focused on: (1) identified the geological and hydrogeological condition and characteristic of the VLLW disposal site, and found the recharge, runoff and drainage route and the head of the groundwater, the boundary and the spatial change of the unconfined aquifer; (2) got the parameters of simulating model by the in situ pumping experiments and correlation coefficients from the soil column experiments and batch tests; (3) calibrated the model with the data of the observed observation wells; simulated the steady state flow and migration of Sr from the repository with fine-particle barrier in 300 years by application the MODFLOW and MT3D module in the Groundwater Modeling System (GMS). The result showed that the barrier was an effective measure for the management of the disposal VLLW.