Conceptual model analysis of interaction at a concrete–Boom Clay interface

The concept for deep disposal of high-level waste in Belgium is based on the supercontainer, which uses a considerable amount of cementitious materials as buffer and backfill. The hosting geological formation is Boom Clay. For the safety assessment of the supercontainer the interaction between the high pH pore water of the cementitious materials and low pH Boom Clay pore water has to be investigated. We develop a coupled reactive transport code in this diffusion-dominated system by making full use of the multi-processors/cores computers and investigate how sensitive the system is to chemical reaction models, i.e., equilibrium (fastest) and shrinking core model (diffusion-controlled dissolution). The results show that only a slight difference with respect to the clogging time can be found . The insensitivity of the clogging time to reaction models might be due to faster decrease of the macro-diffusion coefficients in the system than the rate drop of reaction.