1D and 3D simulation of electrochemical behavior of U/UCl3 and Pu/PuCl3 in molten salt systems

Abstract

In an effort to recycle spent nuclear fuel, molten salt electrorefining of spent nuclear fuel has been investigated as an alternative to aqueous technologies. As performing actual experiments with radioactive material is expensive and difficult, it is useful to create computer models to try and predict the behavior of various designs. In an effort to narrow the gap between computer simulations and reality, a one dimensional model and a three dimensional model of an electrorefiner are developed and tested against experimental data in this work. The one dimensional model was fitted to several cyclic voltammograms of both uranium and plutonium. The model was able to reproduce the cyclic voltammograms, but inconstancies were observed in the case of plutonium. The 3D model was able to reproduce the cell potential of an existing electrorefining system, (i.e., the KAERI HTER) at low values of current. But at higher currents, difficulties were experienced, possibly due to the lack of information regarding the hydrodynamic condition. The newly developed models appear to be useful for the study of electrorefining, but further studies are needed for code validation. One of the main lessons learned in this work is that modelers should be careful about predictions regarding plutonium if it is based on data from a tungsten electrode, as it may misrepresent reality.