The effect of model dimensionality on source terms for the assessment of used fuel disposal

1-D mass-transport models are often used to determine source terms for the safety assessment of used nuclear fuel disposal in geological vaults. In this paper, we investigate the dependence of solubility -controlled source terms on the dimensionality of the diffusion equation used to describe the mass transport of U solution species. Precipitation of U-containing solids downstream from the used-fuel matrix has been included in the model. Such precipitation enhances the dissolution rate of used fuel, and hence, increases the source term. The dimensionality of the diffusion equation is found to have a relatively small effect on radionuclide release for the assumed disposal vault geometries and for time periods less than 104 yr. (author)