Mixed Oxide Fuel, or MOX, is a type of nuclear fuel made from a blend of plutonium and uranium oxides. It is primarily used in nuclear reactors as an alternative to traditional uranium fuel. The use of MOX helps recycle plutonium from spent nuclear fuel, reducing nuclear waste and making better use of existing resources. MOX fuel can improve the sustainability of nuclear energy by allowing reactors to operate more efficiently. It is particularly beneficial in fast breeder reactors, which can generate more fissile material than they consume. This process contributes to a more closed fuel cycle in the nuclear industry.