In a period between 1943 and 1974 radioactive wastes were temporary buried on a special site on the territory of RRC “Kurchatov Institute". The site monitoring held since the end of the 80s showed that contaminants are located not only on the surface and in the ground but they have also spread in groundwater. The paper presents preliminary results of the work on development of numerical models of radioactive contamination migration the waste disposal site. The objectives of the work were to evaluate the existing contamination plume, to determine mechanisms of contaminant migration on the site and to develop a numerical model of radioactive contamination transport that would allow correctly predicting further plume spreading for making necessary engineering decisions. Based on laboratory findings and radiation monitoring data obtained at the waste disposal site and its adjacent areas, there were determined the site hydrogeological structure and parameters, and a geoinformation database was developed. Three-dimensional numerical models of groundwater flow (using the MODFLOW code) and mass transport (using the MT3DMS code) were built and verified against field measurements. Using these models, preliminary predictions of radionuclide migration from the waste disposal site were made.