Capability for Hydrogeochemical Modelling within Discrete Fracture Networks

A new method for simulating solute transport and geochemical interactions within fractured rock is presented. This will be an important capability assessing the safety of radioactive waste disposal facilities that are located crystalline bedrock. Specifically, discrete fracture network (DFN) module ConnectFlow groundwater flow software has been updated to: (i) simulate advection diffusion more than one species (with equations coupled by evolving density viscosity); (ii) model solutes into matrix between fractures; (iii) utilise iPhreeqc library to chemical reactions involving solutes, minerals on fracture/pore surfaces minerals. The performance ConnectFlow’s DFN also significantly improved via parallelisation which allows complex calculations attempted. These developments significant because hydrogeochemistry accurately represented in explicit DFN, rather using approximate equivalent continuous porous medium (ECPM) methods. Illustrative have completed facility spent nuclear fuel at Olkiluoto Finland, former candidate site disposal, Laxemar, Sweden. show simulations provide results qualitatively similar from ECPM calculations. However, a less direct approach, notable differences exist when compared approach.