Model Support for an Out-Reactor-Instrumented-Defected-Fuel- Experiment to Validate the RMC Fuel Oxidation Model

Abstract

An out-reactor fuel oxidation experiment with controlled parameters is being planned to provide important data for validation of a mechanistic fuel oxidation model. In support of this experimental planning, fuel oxidation 2D and 3D models are presented in this paper. The model results indicate that increased defect surface area increases the maximum oxygen stoichiometric deviation in the UO₂ fuel pellet. Model predictions indicate that a stoichiometric deviation of 0.0230 will result within one week of heating a defective fuel element with a 20-mm² sheath defect. The model also predicts that doubling the heating time increases fuel oxidation by 49%. A 2D r-θ fuel oxidation model capable of estimating the required electrical linear power is also presented.