A gas-cooled reactor is a type of nuclear reactor that uses gas, typically carbon dioxide or helium, as a coolant to transfer heat away from the reactor core. This design allows for higher operating temperatures, which can improve the efficiency of electricity generation. The reactor core is usually made of graphite, which also serves as a moderator to slow down neutrons and sustain the nuclear fission process. One of the main advantages of gas-cooled reactors is their inherent safety features. The use of gas as a coolant reduces the risk of overheating, as gas does not boil like water. Additionally, these reactors can be designed to operate at atmospheric pressure, minimizing the risk of pressure-related accidents. Examples of gas-cooled reactors include the Magnox and AGR (Advanced Gas-cooled Reactor) designs.