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Britain's Nuclear Weapons

British Nuclear Facilities

In the United Kingdom nuclear weapons development, acquisition and deployment now occurs entirely within the organizational structure of the Ministry of Defense (MoD). The organization within the MoD responsible for the development, manufacture, and servicing of nuclear weapons is the Atomic Weapons Establishment (AWE), which is under the authority of the Procurement Executive of the MoD. The AWE came into existence on 1 September 1987 through the merger of the Atomic Weapons Research Establishment (AWRE) at Aldermaston, and the Directorate of Atomic Weapons Factories (aka the Royal Ordnance Factories, or ROF) at Burghfield and Cardiff. Prior to its transfer to the MoD in 1973, the AWRE had been under the United Kingdom Atomic Energy Authority since 1954.

AWE Aldermaston
This is the central facility of the British nuclear weapon establishment. It is located at Aldermaston, near Reading, in Berkshire. This facility not only performs most research activities, it also develops weapon designs, and manufactures the majority of weapon components, including nuclear components. It was officially established 1 April 1950 on the site of a World War II airfield. Weapons development work was transferred there from the codenamed "High Explosive Research" (HER) project at Fort Halstead in Kent. The AWE employs about 5000 people.

The facility at Aldermaston covers 880 acres and is broken up into 11 areas. The main administration building is F6.1 in the F area. Area A is known as the Citadel, it occupies the north side of the site and includes the plutonium manufacture and pit fabrication facilities. The A1 plutonium manufacturing buildings were the original fabrication facilities that opened in the early to late 50s. They became badly contaminated in 1978 and were closed, but were reopened in 1982 to manufacture the Chevaline warheads. Operation continued long after its planned closing date, and it manufactured the first Trident warheads. The replacement A90 complex began construction in 1983 and after many delays went into operation in 1991 (5 years late). The A90 complex has 300 glove-box production units, and now handles Trident plutonium component production.

AWE Aldermaston is organized into three major departments relating to weapons development: the Warhead Physics Department, the Warhead Design Department, and the Materials Department.

The Warhead Physics Department is responsible for research and analysis of the fundamental physical processes involved in nuclear weapons. It is divided into the Mathematical Physics Division (conducts theoretical work and computer modelling and simulation), the Warhead Hydrodynamics Division (conducts experimental work in the processes of weapon assembly and disassembly), the Radiation Physics Division (conducts experimental work in both nuclear radiation physics and radiation hydrodynamics), and the Foulness Division (conducts explosive experiments at Foulness in Essex).

The Warhead Design Department develops the complete nuclear weapon design. It is divided into the Weapon Engineering Division ("physics package" design), the Weapon Diagnostics Division (system testing for EMP and nuclear hardening, etc.), and the Electronic Systems Division (fuzing and arming systems development).

The Materials Department develops the materials and processes required to design and manufacture nuclear weapons. It is divided into the Chemistry and Explosives Division, the Chemical Technology Division, and the Metallurgy Division.

AWE Burghfield
The Royal Ordnance Factory (ROF), Burghfield (now AWE Burghfield) was established in 1954 as the final assembly plant for nuclear weapons (the British equivalent of Pantex). It is located 5 miles southwest of Aldermaston and covers 265 acres, although since 1976 it has been omitted from all British maps. It employs some 600 people. Many of the non-nuclear components of nuclear weapons are manufactured at Burghfield - including electronic components, and various casing and component packaging materials. At any given time a number of weapons may be stored there for servicing or disassembly.

AWE Cardiff
Located in Llanishen, 3 miles north of Cardiff, Wales, AWE Cardiff has been involved in nuclear weapon component production since at least 1963. It has a work force of 400 and specializes in high precision components and complex assemblies. Essential parts of thermonuclear weapons, and beryllium/U-238 tampers for fission primaries are manufactured there. Up to 50 tons of depleted uranium may be stored on site. In 1987 AWE Cardiff used 2300 kg of beryllium. Servicing/disassembly of nuclear weapon components also occurs at the facility.

AWE Foulness
This is a 2000 acre test range located on remote Foulness Island on the northern edge of the Thames estuary near Shoeburyness. High explosive tests are conducted at the range, both for weapons development and safety, and to simulate nuclear weapon blast effects.

Sellafield/Windscale/Calder Hall
The main plutonium production site in the United Kingdom is at Sellafield (renamed Windscale when the reactor facility was first built, but now reverted to the original name Sellafield) in north-west England, located on the Cumbrian coast of the Irish Sea. Two 100 MW air-cooled graphite-moderated natural uranium plutonium production reactors (the Windscale Piles) were built there starting in 1950. The first reactor went critical in October 1950, the second in June 1951. These Piles operated until Windscale Pile No. 1 caught fire on 7 October 1957. The fire burned for five days, releasing tens of thousand of curies of radioiodine, and 240 curies of polonium-210 which was being manufactured in the reactor for weapon neutron initiators. During the 11 reactor-years of combined operation these piles produced about 385 kg of weapon-grade plutonium.

Starting in 1956 four more reactors were built at Sellafield - the Calder Hall (CH) Magnox reactors. The Calder Hall reactors entered service between October 1956 and May 1959. These were 180 MW carbon-dioxide cooled reactors with a dual-purpose: they could produce both weapons grade plutonium and electricity. Weapons grade plutonium production tends to interfere with the most economical production of electricity (requiring more uranium for fuel, longer shut down times, and more spent fuel handling), so they were not operated continuously for weapons grade plutonium production. Weapons plutonium production appears to have occurred during 1956-64, the late 1970s, and the mid-late 1980s. These reactors were uprated (as were the identical Chapelcross reactors) to 240 MW in the 1960s, and then downrated slightly in the 1970s.

Sellafield is also the location of British fuel reprocessing facilities, now operated by British Nuclear Fuels Limited (BNFL). The original plant employed the Butex separation process and went into operation on 25 February 1952. The first billets of impure plutonium were produced 31 March 1952. There are now two main plants - the older B205 facility used for Magnox fuel and the newer THORP (thermal oxide reprocessing plant) facility which handles only civilian fuel and is safeguarded. The B205 plant has a capacity of 1500 tonnes of spent fuel per year, compared to 1200 tonnes/year for THORP.

Four more military production reactors, identical to the Calder Hall models but designated "CX", are located at Annan, near Dumfries on Solway Firth in south-west Scotland. Although these reactors have been used for plutonium production, they are also the principal source of tritium for the UK. Although Britain is known to have produced kilogram quantities of tritium before 1970 (6.7 kg of it were exported to the U.S.) the initiation of tritium production at Chapelcross was announced in April 1976. Tritium has apparently been purchased from the U.S. at certain times.

Total Plutonium Production
In addition to the militarized nuclear reactors mentioned above, prior to 1969 spent fuel was diverted from other civilian nuclear reactors as well. Attempting to estimate British weapons plutonium production from these many sources is quite difficult. The best estimates have been made by Albright, Berkhout, and Walker in Plutonium and Highly Enriched Uranium 1996, SIPRI Press. Their net estimate is that Britain produced 3.6 tonnes of weapon grade plutonium in reactors (using fuel burnups of 400-800 megawatt-days/tonne) +/- 0.5 tonnes. About 0.5 tonnes has been effectively lost through reprocessing waste, expenditures in tests, and transfers to the United States. Another 8.7 tonnes of fuel or reactor grade plutonium is also in military inventory.

A British nuclear industry report on plutonium holdings for 1995 showed that British Nuclear Fuels PLC held a total 85 tonnes tonnes of civilian plutonium. 54 tonnes are owned by UK utilities and 31 tonnes owned by BNFL or its overseas customers. Of this 85 tonnes, 39.5 tonnes remains in spent fuel. Only 66 kg was listed as being in MOX fuel exported, none in MOX stock. All separated plutonium had more than 15% Pu-240. The military plutonium stockpile was given as 4.5 tonnes held in various forms by the UK Atomic Energy Authority.

Britain's indigenous supply of enriched uranium is supplied by the gaseous diffusion plant at Capenhurst, originally the site of a Royal Ordnance factory, 25 miles from Risley in Cheshire. Although an enrichment plant was authorized in October 1946, the site was not selected until early 1950. Capenhurst made its initial start up in February 1952, but did not successfully enter operation until 1953 (producing low enriched uranium), and did not produce highly enriched uranium (HEU) until 1954. The plant was given successive upgrades during the fifties, reaching a military significant capacity of 125 kg of highly enriched uranium a year in 1957, and much higher levels in 1959 (as much as 1600 kg/yr, or an enrichment capacity of 325,000 SWU/yr). Capenhurst operated as a source of HEU at full capacity only until the end of 1961. Most of the stages were shut down at that point and the plant converted to low-enriched uranium production for civil reactor use. The 1996 SIPRI estimate was 3.8-4.9 tonnes of HEU being produced, almost all of it in 1959-1961.

The original gaseous diffusion plant was dismantled in 1982, and a new gas centrifuge plant was built called Capenhurst A3. This plant has a capacity of 200,000 SWU/yr and has never produced HEU. After start up ion 1984-85 it produced 4.5% enriched uranium for export to the U.S. either for further enrichment to HEU or in exchange for an equivalent amount of HEU. Since 1993 Capenhurst A3 has been operated as a civilian fuel enrichment plant operated by Urenco under IAEA safeguards.

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