UO2, or uranium dioxide, is a compound made up of uranium and oxygen. It is primarily used as a nuclear fuel in reactors, where it undergoes fission to produce energy. UO2 is known for its high melting point and good thermal conductivity, making it suitable for use in various types of nuclear reactors, including pressurized water reactors and boiling water reactors. In its solid form, UO2 appears as a black or dark brown powder. It is typically manufactured through processes like calcination and reduction of uranium ore. Safety measures are crucial when handling UO2 due to the radioactive nature of uranium, which can pose health risks if not managed properly.