The GRaZ II project deals with the migration of radionuclides in the near field of a repository for radioactive waste in clay formations with focus on the hyper-alkaline water-cement-system. KIT-INE investigates the retention of actinides and lanthanides by clay minerals in presence of carbonate and silicate, cement phases and cement alteration phases. Furthermore, the influence of cement additives (e.g. plasticizer and superplasticizers) on the sorption of actinides is studied at high pH values. One important issue of the project is the thermodynamic modeling of experimental solubility, complexation, and sorption data. The project provides basic knowledge and thermodynamic data needed in the frame of a long-term safety analysis of different repository concepts.