MOX, or Mixed Oxide Fuel, is a type of nuclear fuel made from a blend of uranium and plutonium oxides. It is used in some nuclear reactors as an alternative to traditional uranium fuel. The use of MOX helps to recycle plutonium that is produced in nuclear reactors and can reduce the amount of nuclear waste. MOX fuel can enhance the sustainability of nuclear energy by making use of existing plutonium stockpiles. It is primarily used in pressurized water reactors (PWRs) and boiling water reactors (BWRs), allowing these reactors to operate more efficiently while contributing to energy security and reducing reliance on fresh uranium resources.