Diffusion of HTO, sodium 22 and Caesium in Opalinus clay: a combined field, laboratory and modelling study
Titre du congrès :Clays in natural and engineered barriers for radioactive waste confinement Ville du congrès :Tours Date du congrès :14/03/2005
As indicated by recent investigations, diffusion is the main transport process in consolidated argillaceous formations (e.g. Callovo-Oxfordian, Opalinus Clay) that are foreseen as potential host rocks for high-level radioactive waste repositories. However, reliable data on diffusion properties of these rocks are still scarce, in particular with regard to the behaviour of reactive species. This contribution reports on a comprehensive, internationally supported study, which focussed on the diffusion of non-reactive and reactive species in Opalinus Clay, using a combined field, laboratory and modelling approach. The core part involved the investigation of HTO, stable I-, 22Na+ and stable Cs+ diffusion in an in-situ experiment at the Mont Terri Rock Laboratory in Switzerland. The modelling part was largely aided by diffusion data carried out under laboratory conditions