The main objective of the VEKOCO project is the extension and harmonization of models for the evaporation and condensation heat transfer processes in COCOSYS. The existing models of evaporation and condensation heat transfer will be improved by including various flow regimes and boundary conditions. The new models will be validated as far as possible, implemented in COCOSYS and harmonized according to the code structure. The modified COCOSYS will be applied to a generic containment, to prove the feasibility and importance of the modification.