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Shortly after the discovery of nuclear fission in 1938, the remote possibility that it could be used to provide a powerful bomb emerged.
The key development came early in 1940 from one of the original discoverers of fission, Otto Frisch and a new colleague, Rudolf Peierls. Both were refugees from Nazi oppression working at Birmingham University.
Starting with the Neils Bohr idea that fission in natural uranium was due to the small fraction of uranium 235, calculations indicated that if it could be separated only ‘…about a pound’ was needed for a nuclear explosion. Previous estimates had been up to a couple of hundred tons of natural uranium.
The correct figure is more than a pound, but accurate nuclear data for the calculations was not then available. Even with an error of 10 or 100 times and the weight of the casing and other equipment, an atomic bomb was still a practical proposition.
Britain was at war, so Frisch and Peierls offered the discovery to the Government in a memorandum. A special committee was asked to investigate. It was called the ‘Maud Committee’ after Maud Ray, who looked after Neils Bohr’s children. In July 1941 the Committee produced a report stating that the Frisch Peierls bomb would work. It also noted that if war ended before the bomb was used, ‘...[t]he effort would not be wasted...since no nation would…risk being caught without a weapon of such decisive possibilities’.
In Autumn 1941, work on the atomic bomb began in Britain under the code-name ‘Tube Alloys’, mainly on the problem of separating uranium 235 from natural uranium. The Maud Report was sent to the United States where it convinced influential American scientists that an atomic bomb was possible. Meanwhile, work on the separation process became dogged by technical difficulties. Furthermore, concerns arose about German air raids on the very large installation needed. So if resources were found, should it be built at all?
Eventually it seemed the only way Britain could continue work on the bomb would be in a form of partnership with the United States. After the 1943 Quebec Agreement between President Roosevelt and the Prime Minister Winston Churchill, British scientists went to the new laboratory at Los Alamos to assist American atomic bomb work, by now called the ‘Manhattan Project’. They would also collect experience ‘...for future nuclear affairs’, a hint that Britain still wanted its own bomb.
The uranium bomb seemed simple enough. A piece of uranium 235, less than a critical mass, would be fired at a similar piece in a gun barrel. An atomic explosion would occur when the two met. It was not tested - the first one built was dropped on Hiroshima.
Plutonium could not be used like this because the two pieces would begin premature fission as they approached each other, giving a poor yield. This was a serious problem, because there would only be enough uranium 235 for one bomb before attacks on Japan were due. The solution was complex and British scientists are named as major contributors to it in a Los Alamos document. It was tested on July 16
1945 and a similar device was dropped on Nagasaki. The Second World War ended soon after.
In August 1946 the United States passed the ‘McMahon Act’, stopping wartime collaboration with Britain on nuclear weapons. Nevertheless, the British began the development of their own atomic bomb at Fort Halstead in June 1947.
In charge was Dr William Penney, one of the British scientists at Los Alamos during the war.
The intention was to produce a nuclear device ‘…similar to the [one] that destroyed Nagasaki...’. Over the five years this took, improvements emerged and differences between the American design and British equivalent crept in. When it entered service, there was little left of the original except a general resemblance.
To make the core for the weapon, new facilities for handling plutonium were needed, but Fort Halstead was too small. In September 1949, an airfield near the village of Aldermaston in Berkshire was allocated. On April 1
1950, it re-opened as the headquarters of the British atomic weapon programme.
The bomb, called ‘Blue Danube’, was about 1½ metres in diameter and 7½ metres long – size dictated by the need for a good ballistic shape to enclose a warhead that big.
For the first British test, ‘Operation Hurricane’, a warhead from one of these bombs was installed in a frigate called HMS Plym.
On October 3
1952, it was fired in the Monte Bello Islands off the Northwest coast of Australia. Britain was now a nuclear power. Other tests followed, mainly on the Australian mainland.
In November 1952, the United States tested the first experimental hydrogen bomb. The yield was about 400 times the yield of Hurricane.
In August 1953, the Soviet Union claimed to have the hydrogen bomb. In November 1953, the Royal Air Force received its first Blue Danubes, yield reduced to 10 kilotons to eke out stocks of fissile material.
In March 1954, a huge American explosion in the Pacific showered radioactive material on Japanese fishermen and Marshall Islanders. One of the fishermen died of radiation sickness, prompting world-wide demands for a ban on testing. Nevertheless, in July 1954, the British Cabinet authorised the production of ‘thermonuclear bombs’. In August, all the Atomic Weapon Research Establishment sites became part of the United Kingdom Atomic Energy Authority.
In autumn 1955, planning a trial of so-called ‘megaton’ devices got underway. The first was dropped over the Pacific on May 15
1957. The yield of this experimental ‘hydrogen bomb’ was only 300 kilotons. Two other tests also failed to reach the one-megaton target. Another trial was hurriedly planned for November.
At the beginning of October, the Soviet Union launched the world’s first artificial satellite - something quite unexpected. It was an opportunity for the British to approach the United States about renewing collaboration on nuclear weapons. Congress began to amend the 1946 McMahon Act to allow exchanges of information, stopped in 1946, to restart. Shortly after, the next test of a British hydrogen bomb took place on November 8
1957. The yield was 1.8 megatons. Two more successful series of tests followed.
In August 1958, the amended McMahon Act became law. An agreement was signed between the United States and Britain on sharing information ‘for mutual defence purposes’. It remains a cornerstone of work at AWE to this day.
The British decided to produce a megaton yield American warhead design under the code-name ‘Red Snow’. The equivalent British device needed more development and more nuclear tests – not possible because of an agreed pause in testing by the three nuclear powers.
However, certain aspects of the American design did not meet the British Ordnance Board Requirements. Modifications were embodied and trials carried out in Australia. The warhead would no longer fit the original American bomb casing and a much larger and heavier British one had to be used.
In the early 1960s, the development of a small nuclear bomb began - mainly to replace an earlier weapon called ‘Red Beard’.
Known as WE177, it equipped Royal Air Force and Royal Navy aircraft for over three decades beginning in 1966.
A new implosion system was used in WE177 and the British Polaris warhead which went into Royal Navy Service in 1968.
American warhead designers also adopted this new system, which had been tested in the first British underground test at Nevada in March 1962.
Between 1965 and 1974, there were no British nuclear tests and weapon work tapered off. Our staff began to work on various ‘diversification’ projects, including pilot production of fuel elements for fast ‘breeder’ reactors and equipment for early British satellites and the Concorde supersonic airliner.
Well before Polaris entered service in 1968, it was thought likely to be vulnerable to the anti-ballistic missile system in development by the Soviet Union. It was therefore decided to produce a countermeasure. The starting point was the American Antelope system, itself based on Polaris A3.
Over a decade and half, the British developed it into a capability for degrading the Soviet anti-ballistic missile system radar. This would have given attacking warheads the chance to penetrate this type of defence. The counter-measure became better known as ‘Chevaline’ and it entered service in 1982. By then, Trident had been selected as the next delivery system for the British deterrent.
In 1978 plutonium was found in the lungs of laundry workers on site. Production of fissile components was stopped and Sir Edward Pochin from the National Radiological Protection Board was asked to investigate. This led to a long refurbishment programme and a widespread feeling that nothing like it must ever happen again. One outcome was the construction of a new plutonium facility.
In 1987, the Royal Ordnance factories at Burghfield and Cardiff became part of the Atomic Weapons Research Establishment. The word ‘Research’ was dropped and ‘AWRE’ became ‘AWE’.
In 1993, AWE was put into the hands of a management contractor called Hunting Brae. In 2000, the contract was given to AWE Management Ltd (AWE ML). Contractorising brought a change in management style along with other changes resulting from the end of nuclear tests.
The warhead design capability now has other foundations. The physics of nuclear explosions, for example, can be explored with big lasers. AWE made an early start in this field when Her Majesty the Queen opened the HELEN laser in 1979. A much larger laser facility, Orion, is now under construction.
The behaviour of inert nuclear devices is studied in live explosive tests using large flash X-ray machines. More difficult are studies on later stages of the implosion process, an approach pioneered at AWE and known as ‘core-punch’. The results are used in computations on the most powerful computers available. A much larger facility for ‘core punching’ work is planned for AWE.
Whole areas of science, engineering and technology in AWE’s work are now shared with the outside world, and AWE is doing its best to play a significant part in the scientific and technological life of the United Kingdom.
Information courtesy of the AWE Historical & Educational Collection