Novel and Practicable Approach to Modeling Radionuclide Transport Through Heterogenous Geological Media

This paper describes a novel approach to modelling radionuclide transport through a heterogeneous geological medium. It is assumed that a statistical description of the heterogeneity can be formulated. The approach then essentially consists of three steps: (i) sampling of a large number of potential transport pathways (15‘000 in this example), covering the ranges of properties; (ii) grouping of these pathways in a manner which reflects their importance for radionuclide transport into a small number of “legs” with appropriately averaged properties; (iii) modelling geosphere transport processes in these legs. It is demonstrated that the number of legs required to represent conservatively, but without excessive conservatism, all the transport pathways is small (5 in this example). This result is important for safety assessment, where many different parameter variations may need to be considered and where computational efficiency is often a vital issue.