The light water graphite reactor (LWGR) is a design of nuclear reactor that uses purified graphite as a neutron moderator and light water (H2O) as a liquid coolant. Due to the superior moderating properties of graphite, natural uranium can be used as a fuel, avoiding enrichment.
The design was developed during the Manhattan Project, in a horizontal layout, first used in the 1944 B Reactor, also the world's first large-scale reactor. The Project's Hanford Site constructed nine LWGRs in total for plutonium production, used throughout the Cold War. The Soviet Union subsequently developed a vertical design for use in military plutonium production reactors, constructed at Mayak, the Siberian Chemical Combine in Seversk, 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 design, the only widespread use of LWGRs for commercial nuclear power plants. RBMKs use slightly enriched uranium (<2% 235U).
+Selected examples of LWGRsReactorCountryCriticality dateInitial power (MWth)NotesRefs.B Reactor26 September 1944250First LWGR, twin D and F reactors built under Manhattan ProjectA-110 June 1948100First Soviet plutonium production reactor; in MayakAM-16 May 195430First LWGR to generate electricityAMB-1001 September 1963286SCWR test?N Reactor8 December 19634000Also Hanford Site, shutdown following Chernobyl disasterAMB-20010 October 1967530SCWR test?Chernobyl Reactor 4 (RBMK)26 November 19833200Reactor exploded in 1986, worst nuclear accident in historyJiuquan reactor1966~250China's first plutonium production reactor, military useGuangyan reactor1973~250Third Front facility, military use
See also
RBMK Hanford Engineer Works Hanford Site Void coefficient
References