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 f rom reprocessing and spent-fuel elements. The results of a series of t hermal and near-field thermomechanical analyses for disposal in drifts at three horizons of a repository are described. The rise of the temp erature in the emplacement area and the surrounding rock, the room clo sure of access and emplacement drifts during operational time, followe d by the long-term compaction of the backfill material and the resulti ng stresses in rock salt, are investigated. Two numerical modeling pro cedures 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 be havior of rock salt and backfill material, was used to investigate the thermomechanical effects.