EBSD studies on microstructure and crystallographic orientation of UO2-Mo composite fuels

Abstract

The microstructure of the fuel pellet plays an essential role in fission gas buildup and release and is critical for the safe and continued operation of nuclear power stations. Structural analysis of uranium dioxide (UO2)–molybdenum (Mo) composite fuel pellets prepared at a range of sintering temperatures from 1300 to 1800 °C was performed. Mo micro and nanoparticles were used in making the composite pellets. A systematic investigation into the influence of processing parameters during Spark Plasma Sintering (SPS) of the pellets on the microstructure, texture, grain size, and grain boundary characters of UO2-Mo is presented. UO2-Mo composite show significant differences in the fraction of general boundaries and also special/coincident site lattice (CSL) boundaries. EBSD orientation maps demonstrated that texturing was observed in the pellets fabricated at 1500 °C. The experimental investigations suggest that UO2-Mo composite pellets have favorable microstructural features compared to the UO2 pellet.

Keywords

• Nuclear fuel (UO2)
• Accident tolerant fuel (UO2-Mo)
• SPS sintering
• Microstructure
• Texture
• Grain boundaries