THE SELECTION OF A SORPTION DATA-BASE FOR THE GEOSPHERE MODEL IN THE CANADIAN NUCLEAR-FUEL WASTE MANAGEMENT PROGRAM

A sorption data base has been developed for use in a stochastic contaminant transport model to assess the performance of a used-fuel disposal vault. The data base contains data for sorption on granite and thirteen primary and alteration minerals. An empirical sorption equation has been developed to address the geochemical variability in an intrusive rock formation. To allow sorption data obtained on unconsolidated material to be used in transport calculations through intact rock, differences in the surface areas and, hence, sorptive capacities of the two types of material are recognized by incorporating a surface area term that is a function of porosity. This provides a more conservative and more defensible assessment of radionuclide transport through consolidated geological material.