Bubble morphology in U₃Si₂ implanted by high-energy Xe ions at 300 °C

The microstructure modifications of a high-energy Xe implanted U₃Si₂, a promising accident tolerant fuel candidate, were characterized and are reported upon. The U₃Si₂ pellet was irradiated at Argonne Tandem Linac Accelerator System (ATLAS) by an 84 MeV Xe ion beam at 300 °C. The irradiated specimen was then investigated using a series of transmission electron microscopy (TEM) techniques. A dense distribution of bubbles were observed near the range of the 84 MeV Xe ions. Xe gas was also found to accumulate at multiple types of sinks, such as dislocations and grain boundaries. Bubbles aggregated at those sinks are slightly larger than intragranular bubbles in lattice. At 300 °C, the gaseous swelling strain is limited as all the bubbles are below 10 nm, implying the promising fission gas behavior of U₃Si₂ under normal operating conditions in light water reactors (LWRs).