Studies on inorganic colloids in groundwater samples from the far field of a waste repository

Colloids are small particles (with one dimension less than 1 μm) that are meta-stable. Colloids are ubiquitous in natural waters, and due to their relatively large surface areas, they may combine with pollutants and contaminants making these mobile through the terrestrial environment. A large amount of research is currently directed at understanding the role colloids in contaminant transport and modelling the interaction of these systems. This understanding is particularly important when considering the disposal of nuclear waste. Currently, low-level nuclear wastes are disposed of by shallow burial at the BNFL owned site at Drigg, Cumbria, UK. Predictive modelling of radionuclide transport, in and around the Drigg site, is an essential part of the safety case for continued disposal. However, colloids are not yet included in predictive modelling and the work described in this report attempts to determine whether colloids should, or should not, be included in the models. [Continues.]