Journal of Nuclear Fuel Cycle and Waste Technology

This study presents a revised crackling core model for the description of UO2 sphere oxidation in air atmosphere. For close reproduction of the sigmoid behavior exhibited in UO2 to U3O8 conversion, the fragmentation effect contributing to the increased reactive surface area and the concept of variable grain conversion time were considered in the model development. Under the assumptions of two-step successive reaction of UO2 → U3O7 → U3O8 and final grain conversion time equivalent to ten times the initial grain conversion time, the revised model showed good agreement with the experimental data measured at 599 – 674 K and a lowest deviation when compared with Nucleation and Growth model and AutoCatalytic Reaction model. The evaluated activation energy at 100% conversion to U3O8, 57.6 kJ·mol-1, was found to be closer to the experimentally extrapolated value than to the value determined in AutoCatalytic Reaction model, 48.6 kJ·mol-1.

Keywords

UO2 산화,파편화,쪼개짐심 모델,결정립