Analysing flow and transport phenomena in sparsely fractured media is important for understanding how natural geological environments function as barriers against transport of contaminants and other substances stored in subsurface geological repositories. Sparsely fractured crystalline bedrock is a favourable environment due to weak advective flow and strong retention properties, where the interplay between advective and dispersive flow strongly impacts both inert and reactive transport. The natural bedrock can thereby delay transport of waterborne substances for considerable amounts of time, allowing sorption and decay processes to limit release to the biosphere.

There are however many challenges involved in characterising, quantifying and modelling subsurface flow and transport, mainly due to great geological complexity and variability of the subsurface. Also, there are limitations in availability of field data and uncertainties related to conditioning models against relevant field measurements, in particular related to flow information, and in being able to describe how meaningful uncertainties impact application-significant assessments.

This research theme involves developing and applying methods for numerical fracture network modelling combined with analytical, semi-analytical and algorithmic approaches to investigate flow, flow pathways, and transport processes in geological fractured media, based on application of relevant field data. In particular, applications towards storage of spent nuclear fuel related to the Swedish and Finnish site characterisation campaigns are considered. Here transport of radionuclide particles is of main interest. Also, applications involving carbon capture and storage (CCS) are considered, where caprocks can act as practically impermeable layers to gaseous carbon release from subsurface storage of supercritical carbon dioxide.