M174 Progress Report on the European Joint Programme on Radioactive Waste Management Task 4.2

In the framework of EURAD-GAS joint research project, Task 4 is dedicated to the conceptualization and evaluation of gas migration at the scale of a repository. In this regard, the contributions of the University of Liege are presented on subtask 4.2, which is dedicated to the numerical simulation of gas migration through a “generic repository”. Two-dimensional (2D) plane strain analysis is performed using the finite element method over a space scale of several hundred meters and time scale of 100,000 years. The model dimensions, initial boundary conditions (i.e. mechanical, thermal, and hydraulic), time-varying boundary conditions, and the source terms for heat/gas flow are implemented in accordance with the design specifications from the ANDRA (France) and ONDRAF (Belgium) with certain simplifications. The governing equations of multiphase fluid and heat flow through porous media are also discussed. The simulation results are presented mainly in terms of the evolution of relevant indicators such as pore water pressure, pore air pressure, degree of saturation, stresses, and temperature at the key locations in the system.