Thermal and Thermomechanical Analyses for Disposal in Drifts of a Repository in Rock Salt

In the last few years, several repository concepts have been developed for salt formations to dispose of both high-level radioactive waste from reprocessing and spent-fuel elements. The results of a series of thermal and near-field thermomechanical analyses for disposal in drifts at three horizons of a repository are described. The rise of the temperature in the emplacement area and the surrounding rock, the room closure of access and emplacement drifts during operational time, followed by the long-term compaction of the backfill material and the resulting stresses in rock salt, are investigated. Two numerical modeling procedures were used to obtain the results in this study. A computer code based on the closed-form solution for a heat source in a homogeneous medium was applied to predict the temperatures; a finite-element code, taking into account the nonlinear, temperature- and time-dependent behavior of rock salt and backfill material, was used to investigate the thermomechanical effects.