Diffusion experiments in Callovo-Oxfordian clay from the Meuse/Haute-Marne URL, France. Experimental setup and data analyses

In the large-scale experiments, cylindrical blocks of consolidated clay (30 × 30 cm) were used and the radionuclide was introduced as a compacted “solid source”, which was prepared by mixing the tracer with the clay and compacting to a density similar to the one of the consolidated clay. Compared to conventional in situ tests, this setup is more realistic because the contact between tracer and clay is improved. A 3D analysis of diffusion pathways can be carried out after a thorough sampling of the solid block at the end of the experiment. Graphical representations of experimental results along vertical and horizontal planes obtained according to the samples orientation demonstrated the 3D capacity of this methodology and its capability to evaluate anisotropy and heterogeneities.