The light water graphite reactor (LWGR) is a design of

nuclear reactor A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons ...

that uses purified graphite as a

neutron moderator In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely ...

and light water (H₂O) as a liquid coolant. Due to the superior moderating properties of graphite,

natural uranium Natural uranium (NU or Unat) is uranium with the same isotopic ratio as found in nature. It contains 0.711% uranium-235, 99.284% uranium-238, and a trace of uranium-234 by weight (0.0055%). Approximately 2.2% of its radioactivity comes from ura ...

can be used as a fuel, avoiding enrichment. The design was developed during the

Manhattan Project The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada. From 1942 to 1946, the ...

, in a horizontal layout, first used in the 1944

B Reactor The B Reactor at the Hanford Site, near Richland, Washington, was the first large-scale nuclear reactor ever built, at 250 MW. It achieved criticality on September 26, 1944. The project was a key part of the Manhattan Project, the United States ...

, also the world's first large-scale reactor. The Project's

Hanford Site The Hanford Site is a decommissioned nuclear production complex operated by the United States federal government on the Columbia River in Benton County in the U.S. state of Washington. It has also been known as SiteW and the Hanford Nuclear R ...

constructed nine LWGRs in total for plutonium production, used throughout the

Cold War The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...

. The Soviet Union subsequently developed a vertical design for use in military plutonium production reactors, constructed at

Mayak The Mayak Production Association (, , from 'lighthouse') is one of the largest nuclear facilities in the Russian Federation, housing Production reactor, production reactors (''non'' electricity) and a reprocessing plant. The closest settlement ...

, the Siberian Chemical Combine in

Seversk Seversk (, ) is a closed city in Tomsk Oblast, Russia, located northwest of Tomsk on the right bank of the Tom River. The population was 108,590 at the 2010 census and 109,106 at the 2002 census. It was previously known as ''Pyaty Pochtovy' ...

, and the Mining and Chemical Combine in Zhelenogorsk. China's nuclear weapons program also developed two military plutonium production LWGRs. Reactors used for plutonium production in the nuclear weapons programs of the United Kingdom, France, and North Korea used gas-cooled reactors (GCRs) moderated by graphite, while those used by Israel, India, and Pakistan were believed to be heavy water reactors (HWRs). The Soviet Union also developed civilian power prototypes eventually into the

RBMK The RBMK (, РБМК; ''reaktor bolshoy moshchnosti kanalnyy'', "high-power channel-type reactor") is a class of graphite moderated reactor, graphite-moderated nuclear reactor, nuclear power reactor designed and built by the Soviet Union. It is so ...

design, the only widespread use of LWGRs for commercial

nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...

plants. RBMKs use slightly enriched uranium (<2% ²³⁵U).

References

{{Reflist Nuclear weapons Nuclear power Nuclear reactors by type Nuclear reactors Nuclear weapons infrastructure Nuclear proliferation

See also

References