Advanced Gas-cooled Reactors (AGRs) are a type of nuclear reactor that uses carbon dioxide as a coolant and graphite as a moderator. They are designed to generate electricity by harnessing the heat produced from nuclear fission. AGRs operate at higher temperatures than many other reactor types, which improves their thermal efficiency. These reactors are primarily used in the United Kingdom and are known for their ability to use natural uranium fuel. AGRs have a unique design that allows for a longer operational life and reduced waste production compared to some other nuclear technologies.