"Uranium dioxide" refers to a chemical compound made up of uranium and oxygen. It is a solid material that is commonly used as fuel in nuclear reactors to generate electricity. Full definition
The potassium - atom mouth of an organic molecule grabs one of the oxygen atoms (red) in uranium dioxide. (sciencemag.org)
The fuel rods in most cases consist of uranium dioxide pellets encased in zirconium alloy tubes or cladding. (scientificamerican.com)
The reactor uses uranium dioxide fuel particles that are also coated with graphite so they will not crack and release fission products even in extreme heat. (discovermagazine.com)