High-level nuclear waste management: a geochemical perspective

Atomic Energy of Canada Limited is investigating the concept of the disposal of high-level radioactive waste in an underground vault in an intrusive crystalline rock formation. The environmental impact of such a disposal is, to a large extent, dictated by geochemical processes involving rock-forming minerals, groundwater, and fission products and actinides in the waste. These various geochemical processes impact on the transport of contaminants, including radionuclides and chemically toxic elements, from a used-fuel disposal vault towards the biosphere. The extent and importance of the geochemical processes on contaminant transport are discussed. The predominant processes controlling the velocity of contaminant transport are the various geochemical interactions of the dissolved contaminant species with the minerals lining the surfaces of conductive fractures and fracture systems. Key words: radionuclide, uranium, nuclear contaminant, transport, sorption, diffusion, geochemistry, fission products, granite.