High temperature mechanical properties of fluorite crystal structured materials (CeO2, ThO2, and UO2) and advanced accident tolerant fuels (U3Si2, UN, and UB2)

Abstract

The mechanical interaction between the fuel and cladding that occurs during operation of a nuclear reactor is important to understand as it can lead to cladding failures and release of radioactive material into the coolant. In order to develop better models of the pellet-clad mechanical interactions, the mechanical properties of the fuel at relevant operating temperatures, like the elastic moduli, are needed for current and advanced accident tolerant fuels (ATFs). In this work, elevated temperature nanoindentation and resonant ultrasound spectroscopy were used to measure the moduli and hardness of several fluorite materials (CeO2, ThO2, UO2) and several ATF candidates (ATF) (U3Si2, UN, UB2). In addition, a comparison of the two techniques was performed in this study to independently validate the mechanical properties.