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The first artificial nuclear reactor, the Chicago Pile-1, used nuclear graphite as a moderator. Graphite-moderated reactors were involved in two of the best-known nuclear disasters: an untested graphite annealing process contributed to the Windscale fire (but the graphite itself did not catch fire), while a graphite fire during the Chernobyl ...
Water (sometimes called "light water" in this context) is the most commonly used moderator (roughly 75% of the world's reactors). Solid graphite (20% of reactors) and heavy water (5% of reactors) are the main alternatives. [1] Beryllium has also been used in some experimental types, and hydrocarbons have been suggested as another possibility.
Nuclear graphite is any grade of graphite, usually synthetic graphite, manufactured for use as a moderator or reflector within a nuclear reactor.Graphite is an important material for the construction of both historical and modern nuclear reactors because of its extreme purity and ability to withstand extremely high temperatures.
Graphite moderator blocks in the RBMK can be repaired and replaced in situ, unlike in the other current large graphite moderated reactor, the advanced gas-cooled reactor. [48] Longitudinal cutting in some of the graphite columns during lifetime extension refurbishment work can return the graphite stack to its initial design geometry. [49]
A gas-cooled reactor (GCR) is a nuclear reactor that uses graphite as a neutron moderator and a gas (carbon dioxide or helium in extant designs) as coolant. [1] Although there are many other types of reactor cooled by gas, the terms GCR and to a lesser extent gas cooled reactor are particularly used to refer to this type of reactor.
Sketch of a pebble-bed reactor. The pebble-bed reactor (PBR) is a design for a graphite-moderated, gas-cooled nuclear reactor. It is a type of very-high-temperature reactor (VHTR), one of the six classes of nuclear reactors in the Generation IV initiative. Graphite pebble for reactor. The basic design features spherical fuel elements called ...
The Manhattan Project ultimately used graphite moderated reactors to produce plutonium, while the German wartime nuclear project wrongfully dismissed graphite as a suitable moderator due to overlooking impurities and thus made unsuccessful attempts using heavy water (which they correctly identified as an excellent moderator). The Soviet nuclear ...
The X-10 Graphite Reactor was the world's second artificial nuclear reactor after Chicago Pile-1 and was the first reactor designed and built for continuous operation. [47] It consisted of a huge block, 24 feet (7.3 m) long on each side, of nuclear graphite cubes, weighing around 1,500 short tons (1,400 t), that acted as a moderator.