Porous UO₂ Bodies Produced by Reduction of U₃O₈

Porous UO₂ microspheres, or kernels, can be produced by reduction of fired U₃O₈ kernels to the lower oxidation state. The temperature at which the U₃O₈ kernel is fired is a major parameter in establishing the degree of porosity, and subsequent reduction from the U₃O₈ state must be carefully controlled to prevent formation of internal cracks. Restricting the furnace temperature to < 1000°C and providing small incremental increases in the quantity of reducing gas added to the furnace inert atmosphere produced well-distributed porosity in the ceramic body without creating cracks in the internal structure of the kernel.