A Model to Predict the Ultimate Failure of Coated Fuel Particles During Core Heatup Events

A model to predict the ultimate failure of TRISO-coated fuel particles under hypothetical core heatup events is proposed. Features of the model include the ability to treat the statistical variation of the number of coated fuel particles and to make a thermodynamic estimation of the stoichiometry of irradiated UO₂ kernels and the equilibrium CO pressures. The model predictions agree well with the results of postirradiation heating tests. The thermal creep of pyrolytic carbon, however, must be taken into account to further improve the accuracy of the prediction.