Thermal Simulation of Drift Emplacement for Direct Disposal of Spent Fuel-Evaluation of the Backfilling Technique

Abstract

According to the reference concept for direct disposal of spent fuel in the FRG, large disposal casks will be emplaced onto the floor of repository drifts in salt formations. Licensing of this concept requires demonstration of a suitable backfilling technique, investigations of the behavior of the rock salt and the backfill material. Within preceding tests two different backfilling techniques were investigated under realistic conditions: pneumatic backfilling and slinger backfilling . For the evaluation of the quality of backfill due to the technique applied, various data (in situ-density, particle size distribution, proctor density) were obtained from different areas of a simulated emplacement drift. Both backfilling techniques were evaluated considering safety, technical and economical aspects and a slinger truck was found to be most suitable for the designated purpose.