Fabrication of UO₂-Mo composite fuel with enhanced thermal conductivity from sol-gel feedstock☆

Highlights: • Microspherical UO₃ feedstock utilized for UO₂-Mo pellet fabrication. • Increase in thermal conductivity of UO₂ fuel candidates with secondary Mo phase. • Higher thermal conductivity increases for pellets from microspheres than powders. - Abstract: Fabrication of monolithic UO₂ and UO₂-Mo composites from Mo metal powder feedstock and UO₃ spheres derived from internal gelation was explored. The addition of 10 vol% Mo as a secondary phase to UO₂ led to an increase of up to 30% in thermal conductivity compared to syntheses in which only pure UO₂ was used. Using coarse and fine Mo metal powder feedstock led to different microstructures, influencing the thermal conductivity of the resulting composites.