ABSTRACT
The disposal of heat-generating radioactive waste includes the options of emplacement of casks in drifts of a repository in salt rock, and the emplacement of canisters in boreholes. The use of crushed salt as backfill material is planned to seal drifts and boreholes. The prediction of the long-term behaviour of backfilled drifts and boreholes requires the development of appropriate numerical models. To this end, a new constitutive model for crushed salt based on phenomenological and physical assumptions was developed and implemented into the ANSALT finite element code, including the necessary numerical algorithms for efficient evaluation of the nonlinear time-dependent behaviour of crushed salt. To demonstrate the suitability of the code and the constitutive model, calculations on a large-scale in-situ test of the emplacement of heated casks in drifts are presented which focus on the long-term thermomechanical behaviour of backfilled drifts, e.g. drift closure, backfill pressure, and backfill compaction.
