[en] Models are developed to evaluate the performance of potential geological repositories for high level nuclear wastes systems. Source term models are used to study the stability of the spent nuclear fuel under repository conditions. These models increase the confidence in predicting the evolution and behaviour of the spent fuel matrix and of the radionuclides embedded in it. In this context, we will present a review of the assumptions and approaches considered in most of the studies to simulate the release of the radionuclides embedded in the spent fuel matrix. After this review exercise, we will show the radionuclide release model developed by our group, which is based on kinetic and thermodynamic approaches in order to study the evolution of the spent fuel-water interface as a function of time. The results of this modelling are used as input data in other models that simulate the transport of the released radionuclides through the near-and the far-fields up to the biosphere. Therefore, the model presented in this work should lead to a better definition of the source-term for performance assessment exercises. (Author)