Determining the Exchange Current Density and Tafel Constant for Uranium in LiCl/KCl Eutectic

To obtain Tafel constant and exchange current density data for the U/U3+ couple, a uranium working electrode was examined potentiodynamically at +/- 15 mV overpotential at five temperatures in molten LiCl/KCl eutectic salt. This pre-Tafel region was used to avoid the presence of an observed buildup of material at uranium anodes at Tafel region overpotentials. Data were analyzed using the Oldham-Mansfeld method. The Tafel constant varied inversely with temperature, due to a direct relationship between temperature and transfer coefficient. Exchange current density followed the relation i(o) = 20396e-(4143/T). This temperature-exchange current density relationship yielded an activation energy for the U/U3+ reaction of 34.4 kJ/mol. (C) 2014 The Electrochemical Society. All rights reserved.