Abstract: An apparatus for producing spherical uranium dioxide nuclear fuel particles aving diameters of the order of several hundred microns comprises a source of an aqueous solution of uranyl nitrate, urea and hexamethylenetetramine, a container of a hot organic liquid, i.e. paraffin in which water is insoluble, and a droplet-forming dispenser connected between the source and the container. The dispenser has a constricted nozzle disposed above the free surface of the hot liquid and a piston displaceable in the passage leading thereto by a crank mechanism imparting periodic movement to the piston. The piston has a conical tip which cooperates with a seat along the passage having a larger flow cross-section than the nozzle orifice.