DITUSC targets the consolidation and improvement of the knowledge to predict processes over long timescales in key fields for geological disposal of radioactive waste. Beyond the need to identify, critically assess and eventually define strategies to close existing safety-relevant data gaps and maintaining the know-how in the area of thermodynamics, this WP supports present and future capabilities for the reliable use of thermodynamic model calculations for the performance evaluation of various disposal configurations, for Safety Analyses and the development of the Safety Case.