For the assessment of the long-term safety of a geological disposal of high- and intermediate level radioactive waste and/or spent fuel in the Boom Clay, a better understanding of the migration behaviour of Natural Organic Matter (NOM) is needed because it can act as a carriermolecule for radionuclides. Therefore, a large-scale in-situ migration experiment with 14C-labelled NOM was performed to study the NOM migration behaviour on a large scale (m), on the long-term (> 10 years) and in directions parallel and perpendicular to the bedding plane (transport anisotropy). The numerical modelling tool HYDRUS2D/3D was used to interpret the results. The model was built stepwise, testing the influence of advection, colloid attachment/detachment and anisotropy. The upscaling of previously determined parameters from small scale lab tests was also tested. A classic diffusion-advection description, using parameter values in the range of those obtained in the lab tests, provided already reasonable results. Inclusion of a colloid filtration term in the model significantly improved the simulation. Finally, the model was succesfully tested against a second dataset and the anisotropy of the Boom clay was brought into account.
|State||Published - Nov 2010|
|Event||2009 Migration: 12th International Conference on the Chemistry and Migration Behaviour of Actinides and Fission Products in the Geosphere - Pacific Northwest National Laboratory, Kennewick|
Duration: 20 Sep 2009 → 25 Sep 2009