送交者: hehe 于 2005-2-12, 20:59:59:
回答: 英国的第一个核武器是不是美国提供的 由 HunHunSheng 于 2005-2-12, 13:30:24:
The United Kingdom has four Vanguard class submarines armed with nuclear-tipped Trident missiles. The principle of operation is based on maintaining deterrent effect by always having at least one submarine at sea, and was designed for the Cold War period. One submarine is normally undergoing maintenance and the remaining two in port or on training exercises. It has been suggested that British ballistic missile submarine patrols are coordinated with French ones [1]
Each submarine carries 16 Trident II D-5 missiles, which can each carry up to twelve warheads. However, the British government announced in 1998 that each submarine would carry only of 48 warheads (halving the limit specified by the previous government), which is an average of three per missile. However one or two missiles per submarine are probably armed with fewer warheads for "sub-strategic" use causing others to be armed with more.
The British-designed warheads are thought to be selectable between 0.3 kt, 5-10 kt and 100 kt; the yields obtained using either the unboosted primary, the boosted primary, or the entire "physics package". Although it owns the warheads, the United Kingdom does not actually own the missiles; instead it leased 58 missiles from the United States government and these are exchanged when requiring maintenance with missiles from the United States Navy's own pool.
The United Kingdom is one of the five "Nuclear Weapons States" (NWS) under the Nuclear Non-Proliferation Treaty, which the UK ratified in 1968.
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Number of warheads
In the Strategic Defence Review published in July 1998, the British Government stated that once the Vanguard submarines became fully operational (the fourth and final one, Vengeance, entered service on 27 November 1999), it would "maintain a stockpile of fewer than 200 operationally available warheads" [2] (http://www.mod.uk/issues/sdr/deterrent.htm). The Stockholm International Peace Research Institute has estimated the figure as 185 [3] (http://projects.sipri.se/nuclear/10anuketabl.pdf).
At the same time, the British Government indicated that warheads "required to provide a necessary processing margin and for technical surveillance purposes" were not included in the "fewer than 200" figure [4] (http://www.publications.parliament.uk/pa/cm199798/cmhansrd/vo980714/text/80714w19.htm#80714w19.html_spnew0) . Many estimates for the total number of warheads are around 200, for instance the Natural Resources Defense Council believes that this figure is accurate to within a few tens [5] (http://www.nrdc.org/nuclear/nudb/datab19.asp), although the World Alamanac suggests a potentially much higher value of 200-300.
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History
British nuclear weapons had their genesis in the Second World War when the United Kingdom worked on development of an atomic bomb, initially on their own under the cover name of tube alloys but later as a partner in the American Manhattan Project. The Manhattan Project resulted in the two nuclear weapons dropped on Japan which led to the country's surrender.
The United Kingdom started independently developing nuclear weapons again shortly after the war, Labour Prime Minister Clement Attlee setting up a cabinet sub-committee to examine the feasibility, GEN.75 (and known informally as the "Atomic Bomb Committee"), as early as 29 August 1945. A civilian nuclear program started in 1946 under Air Marshal Viscount Portal of Hungerford. It was based at two former airfields, Harwell in Berkshire (now in Oxfordshire) and Risley in Lancashire were taken over as sites for research and manfuacture respectively. The first nuclear pile, BEPO (Britain Experimental Pile Zero), went critical at Harwell on 3 July 1948.
William Penny, a physicist specialising in hydrodynamics was asked in October 1946 to prepare a report on the viability of building a British weapon. He had joined the Manhattan project in 1944, and had been in an observation plane that accompanied the Nagasaki bomber, and had also done damage assessment on the ground following Japan's surrender. He had subsequently participated in the American Operation Crossroads test at Bikini Atoll. As a result of his report, the decision to proceed was formally made on 8 January 1947 at a meeting of the GEN.163 committee of six cabinet members, including Prime Minister Clement Attlee with Penney appointed to take charge of the programme.
The project was hidden under the name Basic High Explosive Research or BHER (later just HER) and was based initially at Woolwich Arsenal but in 1950 moved to a new site at Aldermaston in Berkshire. A particular problem was the American McMahon Act of 1946 restricting access to nuclear technology. Although British scientists knew the areas of the Manhattan Project in which they had worked well, they only had the sketchiest details of those parts which they were not directly involved in. With the start of the Cold War there had been some warming of nuclear relations between the British and American governments, which led to hopes of American cooperation. However this was quickly dashed by the arrest in early 1950 of Klaus Fuchs, a Soviet spy working at Harwell.
Plutonium production reactors were based at Sellafield in Cumberland (now in Cumbria) and construction began in September 1947, leading to the first plutonium metal ready in March 1952. The first British weapon was detonated on HMS Plym anchored in the Monte Bello Islands on 2 October 1952. This led to the first deployed weapon, the Blue Danube free-fall bomb, in November 1953. It was very similar to the American Mark 4 weapon in having a 60 inch diameter, 32 lens implosion system with a levitated core suspended within a natural uranium tamper, and equipped the V Bomber force which had been developed to carry it. It remained in service until 1963, when it was replaced by the Blue Steel.
A gaseous diffusion plant was built at Capenhurst, near Chester and started production in 1953. By 1957 it was capable of annually producing 125 kg of highly enriched uranium. Additional plutonium production was later provided by two electricity generating Magnox reactors at Calder Hall.
The availability of highly enriched uranium allowed the British to develop a thermonuclear bomb in the 1950s, first detonating a prototype in 1957 but only a few were eventually deployed. Instead, having demonstrated their thermonuclear capability, and with a general thawing again of nuclear relations between the two countries, the British were given access to the design of the smaller American Mk 28 warhead and were able to manufacture copies.
The British also developed an air-launched cruise missile to carry the weapons, Blue Steel, entering service in 1963 and phased out in 1969. It was to have been replaced by Skybolt air-launched ballistic missiles purchased from the United States, and the British consequently cancelled their Blue Steel extended range upgrade and troubled Blue Streak ballistic missile projects. To British consternation, the American government cancelled Skybolt at the end of 1962. Consequently the British purchased Polaris missiles for use in British-built ballistic missile submarines. The British developed an upgrade to system, called Chevaline, to compensate for Soviet ABM system in the 1970s which later generated huge controversy once it became public in 1980 as it had been kept secret whilst costs rocketed. By the time it entered service in 1982 it had cost over a billion pounds.
Vanguard Class SubmarineThe UK also retained air-dropped free-fall WE 177 bombs manufactured in the 1970s until August 1998 when the last was dismantled leaving the four Vanguard class submarines, which replaced the Polaris ones in the early 1990s, as the United Kingdom's only nuclear weapons platform. It has been estimated by the Bulletin of the Atomic Scientists that the United Kingdom has built around 1,200 warheads since the first Hurricane device of 1952. In terms of number of warheads, the British arsenal was at its maximum size of about 350 in the 1970s.
As well as the establishment at Aldemaston, the UK nuclear weapons programme also has a factory at Burghfield nearby which assembled the weapons and is responsible for their maintenance, and had another in Cardiff which built non-fissile components and a 2000 acre (8 km²) test range at Foulness. Since 1993 the sites have been managed by private consortia. The Foulness and Cardiff facilities closed in October 1996 and February 1997 respectively.