Since 1967 radioactive wastes have been disposed of in the Asse II salt mine in Northern
Germany. A signifi-cant part of these wastes originated from the pilot reprocessing plant WAK
in Karlsruhe and consisted of cemented NaNO3 solutions bearing fission products actinides as
well as process chemicals. With respect to the long-term behavior of these wastes the
licensing authorities requested leaching experiments with full scale samples in relevant salt
solutions which were performed since 1979. The experiments aimed at demonstrating the
transferability of results obtained with laboratory samples to real waste forms and at the
investigation of the effects of the industrial cementation process on the properties of the
waste forms. This research program lasted until 2013. The corroding salt solutions were sampled
several times and after termination of the experiments the solid materials were analyzed by
various methods. The results present-ed in this report cover the evolution of the solutions and
the chemical and mineralogical characterization of the solids including radionuclides and waste
components and the paragenesis of solid phases (corrosion products). The outcome is compared
to the results of model calculations. For safety analysis conclusions are drawn on
radionuclide retention evolution of the geochemical environment evolution of the density of
solutions and effects of temperature and porosity of the cement waste simulates on cesium
mobilization.
