The Colloid Formation and Migration (CFM) Project is an international research project for the investigation of colloid formation/bentonite erosion, colloid migration, and colloid-associated radionuclide transport, relevant to both NBS and EBS areas of UFDC. This collaborative project is one of several experimental R&D projects associated with the Grimsel Test Site (GTS) in the Swiss Alps, a URL situated in sparsely fractured crystalline host rock. Colloid-related R&D comprises in situ migration experiments conducted between boreholes in a fracture shear zone; these are complemented by laboratory and modeling studies.
The main R&D objectives, relevant to both natural system and engineered barrier issues, are as follows:
- To examine colloid generation rates and mechanisms at the engineered barrier–host rock boundary under in situ conditions,
- To study the long-term geochemical behavior (mobility, mineralization, colloid formation, etc.) of radionuclides,
- To evaluate the long-distance migration behavior of radionuclides and colloids in water-conducting features in a repository-relevant flow system (i.e., with a very low flow rate/water flux),
- To examine reversibility of radionuclide uptake onto colloids,
- To gain experience in long-term monitoring of radionuclide/colloid propagation near a repository.