Reactive transport modelling has become an integral part of the research carried out in the RWI group. We use a broad range of existing state-of-the-art reactive transport codes, including PFLOTRAN, FLOTRAN, ToughReact and CrunchFlow but we have also developed in-house versions of codes that incorporate new features aimed at solving specific problems. Most recently, we have incorporated a method for approximating Donnan equilibrium between interstitial and anion depleted porosities (i.e. between the free water and the electrical double layer/interlayer porosity, respectively) into FLOTRAN. This allows us to model reactive transport in a clay by explicitly taking into account the effect of charged surfaces of the clay minerals on transport and pore water composition.
Aside from that, current research projects include simulations of thermal-hydraulic-chemical processes in the near field of the nuclear repository at Olkiluoto, Finland aimed at quantifying the corrosion rate of the copper canisters containing the spent nuclear fuel and a similar study related to estimating the corrosion rate of steel canisters in the Opalinus Clay at Mt Terri. We have developed reactive transport models of geothermal systems and CO2 injection systems that unravel the complex interplay of heat transport, solute transport and chemical reactions as well as the feedbacks between chemically induced porosity/permeability changes, fluid flow and transport.
The recent acquisition of two multi-core servers by our group as well as access to the UBELIX cluster at the University of Bern allows us to make use of the HPC capabilities of PFLOTRAN (www.pflotran.org). Simulations involving complex 3D geometries, high grid resolutions and/or geological time-scales have become tractable.
