Parametric studies on confinement of radionuclides in the excavated damaged zone due to bentonite type and temperature change

• Extrusion speed is affected by a change in temperature.
• Na-bentonite will extrude faster than Ca-bentonite.
• Cesium migration in bentonite is enhanced due to decreasing sorption.
• Np migration in bentonite is inhibited due to increasing sorption.
• Bentonite extrusion into a fracture potentially can confine radionuclides.

A parametric study is presented in this paper in order to examine the potential of the extruding bentonite into a fracture in the EDZ to confine radionuclides. Radionuclide migration of cesium and neptunium were studied at elevated temperatures and for a sodium- and calcium-type bentonite. Parameter values were obtained based on empirical studies for hydraulic conductivity, molecular diffusion, and sorption. Results indicate extrusion speed is affected by temperature changes. Elevated temperatures also affect radionuclide migration. For Cs, migration is enhanced due to decreasing sorption, while Np migration is inhibited due to increasing sorption. The potential to confine radionuclides is favorable, and the choice of bentonite does not seem to affect radionuclide confinement in the extruding region.