SAFT-VRE is an extension of the statistical associating fluid theory for potentials of variable range (SAFTVR) that can be used to describe the thermodynamic properties of strong-electrolyte solutions. Here the SAFT-VRE method is used in a flowsheet simulation code to calculate the densities of uranyl nitrate/nitric acid aqueous solutions and the activities of species that are needed for the calculation of the distribution coefficients of nitric acid and uranium in the nitric acid-30% tributyl phosphate (TBP) extraction system that is used in an advanced PUREX process for the reprocessing of spent nuclear fuels. Simulation results of both single-stage extraction experiments and of a multistage flowsheet test showed that the SAFT-VRE method can be used in flowsheet simulations with reasonable accuracy, thus demonstrating for the first time that thermodynamically-based mesoscale SAFT-VRE models can be linked to the macro-scale model of the PUREX solvent extraction process.