English 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.
