Review of sintering and densification in nuclear fuels: Physical mechanisms, experimental results, and computational models

This work is a review of two density changes common in UO₂ nuclear fuel: sintering and irradiation-enhanced densification. These density changes must be understood in order to predict fuel behavior, increase fuel lifetime, and design safer and more economical reactor fuels. The physical causes of each dimensional change are summarized. Then a summary is given of published experimental data as well as conclusions that can be drawn from that data. Finally, the most commonly used models for predicting these behaviors are summarized and compared based on the type of model, assumptions in the model, and the physics accounted for in each model. Models are categorized as empirical, semi-empirical, continuous, or microstructural. Commonly used models are presented, summarized, and compared based on the model category, assumptions, and physics that are included in the models. Finally, recommendations are given for future model development.