Consistency of the strontium transport parameters in Boom Clay obtained from different types of experiments: accounting for the filter plates

Previously, different types of experiments with Boom Clay did not lead to a consistent value for Sr of the product R of the diffusion accessible porosity  and the retardation factor R. The nearly flat concentration profile measured in a through diffusion experiment could not be explained. A reason is that the filter plates confining the clay sample have not been taken into account. Therefore, for Sr and tritiated water, the apparent diffusion coefficient (Dapp) and R are measured in through diffusion experiments on filter plates. Taking into account the filters, the outlet fluxes and the Sr profiles in the clay of both Sr through diffusion experiments, are described well with (i) the previously estimated Dapp in the clay of 7 × 10-12 m2/s, (ii) an apparent filter diffusion coefficient in the range 2 × 10-12 m2/s to 5 × 10-11 m2/s (vs. 1 × 10-11 m2/s measured in the filter through diffusion experiments), (iii) a clay R in the range between 5000 and 22000, and (iv) a filter R between 0.3 and 0.6 (in agreement with the filter through diffusion measurements). The evolution at the inlet could not be described well with the above parameters.