The deep geological disposal of high level radioactive waste has been chosen as the preferred final disposal option in Switzerland and Hungary for many years. As a potential host rock for the high activity radioactive waste repository two argillaceous formations, the Boda Claystone Formation in Hungary and Opalinus Clay Formation in Switzerland were selected by the responsible authorities PURAM and NAGRA, respectively.
The objectives of this project are to make specific contributions to the safety assessment of the future radioactive waste repositories through an understanding of relevant retention/retardation mechanisms and processes, and to provide the necessary models and databases. In order to investigate sorption mechanisms on a molecular scale, high-sensitivity measurements are planned on the microscopic scale. Although some of laboratory scale equipments and methods are suitable for specific analytical tasks for specific elements, the versatility and the extremely high-sensitivity of synchrotron radiation (SR) based X-ray microanalytical techniques are even more advantageous. SR based methods are also advantageous in the sense of non-destructivity, therefore, the analyzed samples are still available for other methods, also those requiring digestion of the samples. SR-based microanalytical tools are appropriate for elemental analysis (microscopic X-ray fluorescence – micro-XRF), crystalline phase analysis (microscopic X-ray diffraction – micro-XRD), as well as chemical state and local structure information (X-ray absorption spectrometry – XAS).