[SY-B7] Symposium B-7

[SY-B7] Modeling swelling in U₃Si₂ nuclear fuel using a multi-scale computational approach

^○Larry Aagesen¹, Karim Ahmed², Benjamin Beeler¹, Daniel Schwen¹, Yongfeng Zhang¹ (1.Idaho National Laboratory, United States of America, 2.Texas A&M University, United States of America)

U₃Si₂ is a leading candidate for application as an accident-tolerant fuel for commercial nuclear power generation. Due to U₃Si₂’s high thermal conductivity relative to conventional UO₂ fuel, it is believed to have a wider margin to melting/relocation in accident scenarios. However, based on limited experimental data, it is believed that U₃Si₂ undergoes much more significant swelling. To predict the swelling of U3Si2, a multi-scale computational approach has been developed. A phase-field model of fission gas bubble was developed, which tracks vacancies on the U lattice sites and Xe atoms as defect species. The proportional swelling of the fuel was assumed to be equal to the volume fraction of the bubble phase. The phase-field model was parameterized using density functional theory and molecular dynamics calculations. The incorporation of the swelling predictions to engineering-scale fuel performance models will be discussed.