Coupled Hydrochemical Modeling for the Optimal Design of an In-situ Redox Experiment

P. Trinchero[1], J. Molinero[1], G. Román-Ross[1], A. Nardi[1], L.M. De Vries[1], T. Karvonen[2], P. Pitkänen[3]
[1]Amphos 21, Barcelona, Spain
[2]WaterHope, Helsinki, Finland
[3]Posiva, Eurajoki, Finland

In this work, we present a number of scoping calculations that have been carried out to design an in-situ redox experiment (Figure 1) focused on assessing potential changes in the pH and redox conditions and in the buffering capacity of the Olkiluoto bedrock (i.e. the site for the Finnish spent fuel repository). A characteristic of these models lies in the need to integrate prior information, computed by a complex surface-subsurface 3D model (i.e. flow velocity field computed over the transmissive zone HZInf7 - see Figure 2), with a number of nonlinear reactions. This coupling has been achieved by using a Java interface (Nardi et al., 2012) that links COMSOL Multiphysics with the geochemical simulator PHREEQC (Parkhurst and Appelo, 1999).

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