Nuclear Reactor Types
Magnox Reactors
Being graphite moderated and gas cooled, Magnox reactors owe much to the earliest reactor designs. The name Magnox is derived from the magnesium alloy used to encase the fuel, which is natural uranium metal. Fuel rods are loaded into vertical channels in a core constructed of graphite blocks. The system furthermore involves control rods, which can be inserted or withdrawn from the core to control the rate of fission. The assembly is cooled by carbon dioxide gas, blowing past the fuel cans, which are designed to enhance heat transfer. The hot gas then converts water into steam, powering a generator.
AGR
In order to improve cost efficiency, it was necessary to increase temperatures and achieve higher power density in the former Magnox reactor. This very objective entailed replacing magnesium encasings with stainless steel claddings and diverting from uranium metal to uranium dioxide fuel. The Advanced Gas-Cooled Reactor, or AGR was born.
CANDU
Created in Canada and subsequently globally exported, this heavy water reactor is the only one of its kind. Unenriched uranium dioxide is held in zirconium alloy tubes. The fuel is cooled by pumping heavy water under high pressure through the system, subsequently powering a steam generator.
PWR
The term radioactivity was coined by Marie- and Pierre Curie after the term radiare Latin for “shining”. Their research on the penetrating rays in uranium and the discovery of radium launched an era of using the latter element for the treatment of cancer. Their exploration of this field could be seen as the first peaceful use of nuclear energy.
RBMK Reactor
This water-cooled graphite-moderated reactor design with a positive void-coefficient was developed by Soviet scientists and implemented in the city of Obninsk in 1954. The layout consists of a large graphite core, containing enriched uranium dioxide fuel, next to which water is pumped through and allowed to boil. The generated steam hence powers electrical turbo-generators. Although this design proved itself cost-efficient, it contained multiple fatal flaws which, in 1986, led to the Chernobyl disaster.