Regional Flow and Transport Simulation of Liquid Radioactive Waste Disposal at the Siberian Chemical Combine for Long- and Super-Long-Term Postinjection Periods

Regional groundwater flow and transport models were substantiated for the site of underground disposal of liquid radioactive waste from the Siberian Chemical Combine. The migration of a neutral component and two radionuclides (Sr-90 and U) in groundwaters was predicted for the long- (1000 years) and super-long-term (10 000 years) periods using the microdispersion and macrodispersion approaches. A local modelinsert of the lithological and hydraulic heterogeneity was developed for substantiating the macrodispersion parameters. The simulation results show that, during the long-term period, the contaminated waters will be mainly localized within the injection zone (below buffer horizon IV), and during the super-long-term period about 90% of the total amount of neutral wastes will be discharged into the drainage network, whereas uranium will be fully retained within the disposal site.