Natural flake graphite of laminated structure is aeolotropic, and it is difficult to press spherical fuel element because of low bulk density and tap density of graphite micro-powder.

• 天然鳞片石墨为层状结构呈各向异性,且天然鳞片石墨微粉的松装密度和振实密度太低,不利于球形燃料元件的压制。