Keywords:Radioactive waste disposal, Compacted bentonite, Calcium carbonate, Electromigration
Calcium carbonate precipitation may occur in bentonite which will be used as an engineered barrier in disposal of radioactive waste generated from Fukushima nuclear accident. In this study, an electrokinetic method was used to enhance the calcium and carbonate migration in saturated sodium bentonite. Sequential extraction method was developed to quantify different states of cations and anions in compacted bentonite after the electromigration experiment. The conditions for CaCO3 precipitation are discussed based on the spatial distribution and chemical states of ions both in the interlayer and in the pore water of bentonite.