Impact of spheroidization of UO$_2$ powders on the filling of press molds
Résumé
The integrated technology demonstrator called ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) is a sodium-cooled fast reactor (SFR) currently in design phase. This reactor will use a fuel different to that of pressurized water reactors (PWR). SFR fuel has specific characteristics that require a suitable manufacturing process. Especially, suitable rheological properties are required for the powder feeding the press molds. There is no standard and universal method to characterize the flow of powders, there are direct (shear cells) and indirect methods (dynamic flowability measurements like FT4 Powder Rheometer). We use both methods the shear cell measurement permits to determine the powder flow in quasi-static system whereas the VFR measurement shows the flow index in dynamic system. A spheroidization operation could precede the shaping of pellets to improve the filling properties. In this study we observe the influence of particles morphology on the rheological properties of UO$_2$ powders. Different particle morphologies are investigated in order to obtain a good' filling conditions, i.e. homogeneity and reproducible filling. For that, the behavior of the studied powder needs to be well-understood. It cannot be characterized by a single index but by a combination of different tests.
Origine : Fichiers produits par l'(les) auteur(s)