Site Specific Sorption Data for the Asse Salt Mine

The focus of this contribution is to report sorption data for Asse salt mine. The purpose of the experimental program was to obtain data based on site and scenario specific considerations for use in terms of Kd-values for the emplacement rooms in performance assessment calculations. A range of materials, solutions and radionuclides was studied, including the variation of solid to liquid ratio and the effect of complexing agents with EDTA chosen as the representative. Observed sorption kinetics is compared to observations in model systems, where a fast and a subsequent slow sorption step occur. Calculations on a model system are performed assuming a similar sampling procedure as in the experimental program. It is concluded that the observed kinetics can at least partially be explained by the experimental procedure. Problems in obtaining and applying the site specific sorption coefficients in performance assessment are addressed. Special focus is in this respect on the need to develop (i) more mechanistic understanding of sorption processes in complex systems (ii) more complete sorption data sets and (iii) pragmatic sorption models capable of handling high salt concentrations.