The first atomic bomb was tested as part of the top secret Manhattan Project in the desert of New Mexico in 1945. The project was led by the United States with the support of the United Kingdom and Canada. Here are other important events in the history of the UK’s own scientific and military development of nuclear weapons:
At the Cavendish Laboratory in Cambridge James Chadwick performed a series of experiments that disproved the gamma ray hypothesis, which suggested that gamma radiation was the radiation produced when polonium and lithium were combined. This was thought to be true as it was not influenced by an electric field. Chadwick conducted an experiment which found that new radiation was made of uncharged particles with around the same mass as the proton: the neutron. This discovery won Chadwick the Nobel Prize for Physics in 1935. He was part of the British MAUD Committee which concluded that it was possible to develop nuclear weapons – and it was likely to occur. During World War II he was the head of the British division of the Manhattan Project in Los Alamos where he collaborated with nuclear scientists in the US on the development of atomic weapons. He was also responsible for ensuring a British envoy was present at the bombing of Nagasaki.
The UK’s own nuclear weapons development began in October 1952 with its first independent testing. Codenamed ‘Operation Hurricane’, the tests were carried out in in a lagoon of the Monte Bello Islands in Western Australia. The bomb was detonated inside the Plym which was anchored just off Trimouille Island in order to test the effect of a bomb smuggled inside a ship to a port (which was something of great concern to the UK). The resulting explosion created a six metre deep and 300 metre wide crater on the seafloor.
Further nuclear weapons tests were carried out in Australia and on Christmas Island in the Pacific up until 1963. From the 1960s onwards the UK carried out tests in partnership with the USA, with the last to take place in 1991. In total the UK has carried out between 44 and 45 test explosions. In 1963 the US, UK and Soviet Union agreed to only carry out tests underground and in 1996 the UK agreed to stop testing nuclear weapons altogether by signing the United Nation’s (unenforced) treaty.
In October 1957 Britain’s worst nuclear accident occurred when a fire broke out in the reactor of the Windscale Nuclear Power Plant in Cumbria where the reactors were producing plutonium for the weapons programme. The fire burned for three days and at its worst eleven tons of uranium were burning. Radiation caused an increase in thyroid cancer cases in the fallout area. After the event the Board of Enquiry found the clean-up crew to be "prompt and efficient and displayed considerable devotion to duty". The disaster was ranked 5 out of 7 on the International Nuclear Event Scale.
In December of 1962 President Kennedy met with Prime Minister Macmillan to discuss the sale of nuclear weapons after Kennedy cancelled an agreement to sell the Skybolt V-bomber. The leaders agreed on the sale of a US ballistic missile system (launch tubes and firing system) to be launched by a UK developed submarine with the UK’s nuclear warheads. The sale includes the use of Scotland’s Holy Loch as a base for the US’s nuclear submarines. In June of 1968 the HMS Resolution begins patrolling with its Polaris missiles to provide continuous-at-sea-deterrence, meaning at least one submarine is carrying nuclear weapons at sea at any given time. Just one month later the UK signed the Treaty on the Non-Proliferation of Nuclear Weapons with the US and Russia. The Trident submarine weapons system followed on from the Polaris system in December of 1994 with the first patrol of HMS Vanguard. Submarines are now the UK’s only remaining mode of delivering nuclear weapons, but the debate about whether to scrap, update or replace Trident is ongoing.