Reactive Transport Processes in Compacted Bentonite

A.E. Idiart[1], M. Pekala[1], A. Nardi[1], D. Arcos[1]
[1]Amphos 21, Barcelona, Spain

The Swedish Organization for Radioactive Waste (SKB) is considering disposal High Level Wastes in a deep underground repository. Bentonite clay is planned to be used in the near-field of the waste packages as buffer material. The buffer is expected to provide a favorable environment with limited radionuclide migration due to slow diffusion and retardation by sorption and cation-exchange effects. A modeling of these bentonites has been undertaken to verify whether a reactive transport model with cation-exchange can explain the observed experimental patterns. This work has implemented a reactive transport model using the Subsurface Flow Module and a set of DAE. The obtained results agree well with experimental data and provide insight into the processes behind solute transport in bentonite.