Method for making mixed oxide (U,Pu)O2 nuclear fuel pellets from non-castable UO2 powder

摘要

A process for manufacturing (U,Pu)O₂ mixed oxide nuclear fuel pellets. In a first blending operation, PuO₂ is mixed with a UO₂ powder and/or fuel manufacturing scrap, forming a first blend. The first blend is micronized and sieved to form a conditioned first blend. Non-free-flowing UO₂ is selected as a second portion of UO₂. The second portion of UO₂ is mechanically granulated to form granulated free-flowing UO₂. In a second blending operation, the conditioned first blend is further mixed with the granulated free-flowing UO₂ and possibly scrap. Lubricants and/or poreformers are added. The blend is pelletized and sintered. During granulation, the non free-flowing UO₂ is compressed to form tablets. The tablets are then crushed until a free-flowing crushed material has been formed. At least one portion of this free flowing crushed material is used in the second blending operation.