Quantitative Procedure to Determine the Rate of U3O8 Formation on UO

Abstract

The literature on the rate of U₃O₈ formation on UO₂ has been critically reviewed. Even after inappropriate data have been culled, there remains a large uncertainty in the reported values of the activation energy. We have thus developed an X-ray diffraction technique to measure specifically U₃O₈ formation on the surface of UO₂ pellets, and an appropriate mathematical model to analyse the kinetic data. The resulting Arrhenius expression yields a value of 146 ± 10 kJ mol^-1 for the activation energy for the formation of U₃O₈. The kinetic data presented herein can be used to assess the performance of used fuel under dry air storage conditions.