Flow properties of uranium dioxide control-shaped powders: Link with the particle morphology and size of asperities

In a nuclear fuel fabrication process, knowledge of flow properties is essential. Indeed, fuel manufacturing is based on a powder metallurgy process and each of its stages requires a good flowability. In this work, we propose to establish a quantitative link between the morphology and asperities of uranium dioxide powder particles and their flow properties. To this end, model uranium dioxide powders with a controlled particle size distribution and a controlled shape have been fabricated. A method was used, based on the image analysis resulting from the 2D projection of each particle, to characterize the morphology of the powder particles. These images were obtained using a scanning electron microscope on resin-coated particles. The morphological parameters chosen to characterize the powder are elongation, circularity and solidity. Rheological properties are obtained using an FT4 powder rheometer: the powder undergoes different tests (permeability, compressibility, and shear) to quantify its flowability. We were able to confirm that the finer the particles making up the powder, the worse the powder flow, and that the more spherical the particles making up the powder, the better the powder flow. Finally, we characterize the asperities of uranium dioxide powder particles and discuss the link between flow and Bond number using our data and data from the literature. • Model uranium dioxide powders with a controlled size and a controlled shape. • A quantitative link between UO 2 powder morphology/asperities and flow properties. • UO 2 particles asperities measurement. • Link between flow function coefficient and Bond number.