GPR Measurements for Spatial Investigations at the Asse Salt Structure

Abstract

The potash mine in the Asse salt structure, now used as repository for nuclear waste, is in some parts going to be refilled for mechanical stability reasons. As a part of that work, old blind shafts were prepared and offer the option for ground penetrating radar (GPR) measurements on vertical profiles in the mine. Horizontal profiles can be carried out in accessible drifts at the margin of the mine. The salt structure has mainly been explored from the surface by seismic measurements and boreholes. Due to the accuracy of these investigations and the openings and drifts inside the mine, the geological composition of the salt structure is known. East of the mine, the geological model is based on little information. Therefore, boreholes were drilled in that region and direction sensitive borehole tools provide additional structural knowledge. Vertical, horizontal and radial profiles in the mine have allowed imaging the complex geological structural information by mapping distance and direction of reflecting objects. With these results, a three dimensional geological model of the salt structures can now be optimized. This project is conceived and controlled by the operator of the mine the German Federal company BGE (Bundesgesellschaft für Endlagerung). BGR is commissioned amongst others for GPR measurements.