PORE STRUCTURE, FLUID FLOW AND RADIONUCLIDE TRANSPORT IN GEOLOGICAL BARRIER MATERIALS

摘要

This work presents the preliminary results of using variousand complementary approaches to investigating porestructure of, and resulting anomalous fluid flow andradionuclide movement in, generic geological barriermaterials (shale, clay sediment, crystalline rock, tuff, saltrock). The experimental approaches include mercury intrusionporosimetry, small angle neutron scattering, and vacuumsaturation followed with micro-scale elemental mapping withlaser ablation-ICP-MS. Pore size is not the major contributorto slow fluid flow and radionuclide transport, the anomalousbehavior appears to be caused by low pore connectivity. Forexample, the shales have a predominant presence of nanoscalepore-throat sizes, and very limited (and steep decline of)edge-accessible pore spaces from vacuum saturation andsubsequent tracer mapping tests. In summary, our evolvingcomplementary approaches provide a rich toolbox for tacklingthe pore structure characteristics in tight geological barriermaterials, and associated fluid flow & radionuclide transportbehavior, dictates how these media will perform in naturaland engineered systems in a waste repository.