Nuclear fuel pellets. Box of nuclear fuel pellets ready to be loaded into fuel pins at a nuclear fuel assembly factory. These nuclear fuel pellets contain mixed oxide (MOX) fuel, which is a mixture of plutonium and uranium. The uranium and plutonium are mixed together as a powder and turned into the ceramic (oxidised) fuel pellets seen here. The fuel pellets are then loaded one on top of the other into long fuel pins, up to 3 metres long, and used to create controlled nuclear fission reactions in nuclear reactors. Millions of these pellets are used in a nuclear reactor. This is the Melox factory in Marcoule, France. Photographed in 2004.