AGRs - Advanced Gas-Cooled Reactors are the second generation of British gas-cooled reactors. They use graphite as a moderator and are cooled primarily with carbon dioxide, however nuclear generation does not emit any CO2. The first AGR in commercial operation was Hinkley Point B in 1976.
Moderator - In nuclear engineering, a neutron moderator is a medium that reduces the speed of the nuclear fission reaction; or, in other words, slows down the neutrons to improve the efficiency of the nuclear reaction.
Graphite bricks - The core of the AGR is made up of graphite bricks with channels that contain the fuel elements and control rods.
Fuel elements - AGR fuel consists of stainless steel pins. These pins are made up of small pellets containing uranium, which are built into a graphite sleeve. Seven or eight smaller fuel elements are fixed together vertically to form one large fuel element.
Control rods – These control the reactor power. The graphite core contains channels for the boron steel control rods, which can be raised and lowered to control the reactor power.