Abstract

Calculation of migration of radionuclides through the geosphere, within safety assessment studies for nuclear waste disposal in deep geologic formations, are often carried out with models taking sorption into account. There is a lack of knowledge about the conditions of the experiments underlying the available sorption data. Therefore the RIVM decided to participate in a Finnish intercalibration study, which was supported by the Expert Group on Geochemical Modelling. The sorption experiments have been performed by R.M.J. Pennders of the Laboratory of Radiation Research and supported by G.C. Wijland of the Laboratory of Soil and Groundwater Research. For cesium the sorption-value (Kd) after one week of contact and a solid/solution ratio of 1 g of potassium feldspar to 10 ml of a standard synthetic groundwater was 10.65. The mixing ratio did not seem to have an influence on the resulting Kd-value. From experiments performed with uranium after one week of contact and a mixing ratio of 1:10 a Kd-value is not very reliable.