Small, ceramic urania spheres can be prepared for use as nuclear fuel by internal chemical gelation of uranyl nitrate solution droplets. Acid-deficient uranyl nitrate solutions up to 3.4 M in uranium with N03'/U mole ratios of 1.5 to 1.7 are prepared by dissolution of U308 or U03. Decomposition of hexamethylenetetramine dissolved in the uranyl nitrate solution releases ammonia to precipitate hydrated U03. Previously established flowsheet conditions have been improved and modified at ORNL and have been applied to prepare dense U02 spheres with average diameters of 1200, 300, and 30 pm. The 1200and 300-^m U02 spheres were prepared by gelation in trichloroethylene at 50 to 65 °C; 2-ethyl-1-hexanol was used as the gelation medium to prepare 30-;um U02 spheres.