Porosity Effect on Fission-Induced Creep Behavior of Irradiated U-10Mo Alloy

Fission-gas-induced porosity significantly affects the irradiation creep behavior of U-10Mo alloy, which is critical for the safe and reliable design of fuel elements. In this study, a representative volume element (RVE) model with randomly distributed pores is developed to investigate the porosity-dependent irradiation creep of U-10Mo alloy. Based on homogenization theory and macroscale dimensional variation, the effective creep strain and creep rate are obtained, and the contributions of the U-10Mo skeleton and pores to the macroscale creep are quantitatively distinguished. Systematic parametric studies examine the effects of fission rate, tensile stress, and porosity on the effective irradiation creep response. The results show that (1) the effective creep strain scales linearly with both fission rate and applied stress and increases significantly with porosity; (2) the creep deformation of the U-10Mo skeleton dominates the macroscale creep, contributing from approximately 85% at 10% porosity to approximately 63% at 25% porosity, while the pore contribution increases with increasing porosity; (3) a porosity-dependent effective irradiation creep rate model is established, with only two fitting parameters, and it exhibits good internal consistency and extrapolability. Additional simulations at porosities of 5%, 18%, and 28% agree well with the fitting curve. The model is further validated by a U-10Mo/Al monolithic fuel element irradiation-induced deformation simulation, where the predicted thickness deformation shows reasonable agreement with experimental data. This work provides a practical and physically grounded model for multi-scale thermo-mechanical coupled analyses and engineering-scale fuel performance simulations of porous U-10Mo fuels.