The AMPEDEK project: Geochemical, Petrophysical and Rock Mechanical Characterization of the Crystalline Basement in Germany for High-Level Radioactive Waste Disposal

The long-term and safe disposal of high-level radioactive waste remains a major concern in both scientific and public discussions. In Germany, the Federal Company for Radioactive Waste Disposal (BGE) is responsible for selecting a suitable repository. In the first phase of the site selection process, the BGE defined several sub-areas, seven of which lie within the crystalline basement. However, many of these areas lack detailed information on the mineralogical, geochemical, petrophysical, and mechanical properties of the crystalline rocks, limiting the ability to assess their suitability. To address this gap, the AMPEDEK project aims to build a comprehensive reference database for crystalline basement rocks in Germany. In the initial project phase, data from over 40 published sources were compiled and integrated. Subsequently, around 650 cylindrical plugs from drill cores and outcrops were systematically analysed for petrophysical, mechanical, thermal, and geochemical properties. Triaxial tests and thermal conductivity measurements were conducted at elevated temperatures (up to 275 °C) and pressures (up to 30 MPa) to simulate reservoir conditions. The resulting database comprises ~25,700 data points for up to 34 rock properties derived from over 8,200 samples across more than 3,400 locations in eight federal states. The results reveal a wide range and variability in rock properties, reflecting the geological complexity of Germany’s crystalline basement. Lithology-specific trends in density, magnetic susceptibility, and thermal conductivity were observed. HT/HP experiments show significant changes in permeability and thermal properties with increasing temperature and pressure, underlining the need for site-specific characterization.