This article first appeared in the October 2012 issue of BBC History Magazine
It took two ships almost a year to travel halfway across the world. They had left Britain to sail to the Montebello islands, an archipelago 80 miles off the north-western coast of Australia. The ships carried a naval crew and royal engineers, who had a specific task: to prepare the site for the testing of Britain’s first atomic bomb.
On 3 October 1952 at 9.24am local time, just after midnight in London, Britain entered the nuclear age. The test was of a plutonium bomb with a yield of approximately 25 kilotons. The detonation was awe-inspiring. William Penney, the scientific director and a noted mathematical physicist, described the moment he witnessed the explosion: “The sight before our eyes was terrifying – a great greyish cloud being hurled thousands of feet into the air and increasing in size with astonishing rapidity.” The cloud itself was a strange Z-shape, very different to the customary mushroom clouds associated with nuclear weapons tests. The reason was simple: the device had been placed three metres below the waterline and so the mixture of water and mud changed the cloud’s shape.
The rationale for this was also straightforward. The experiment was designed not only to confirm that the science had been mastered, but also to test the effects of a detonation in shallow water. This was exactly the sort of result that might be produced if the Soviet Union smuggled one of its atomic bombs into a harbour in the United Kingdom: what might be the opening salvo of a third world war.
The original idea that the splitting of heavy elements could be harnessed as a weapon was proposed by two émigré scientists in 1940. Otto Frisch and Rudolf Peierls, both from the University of Birmingham, showed that the ‘super-bomb’, as they termed it, could be constructed. The two physicists were clear about what they were proposing: “Then energy liberated in the explosion of such a super-bomb… will, for an instant, produce a temperature comparable to that in the interior of the sun. The blast from such an explosion would destroy life in a wide area. The size of this area is difficult to estimate, but it will probably cover the centre of a big city.” The only defence against an atom bomb, they argued, was the threat from a similar bomb.
The Frisch/Peierls memorandum hit a nerve: Britain was at war and in February 1940, when it was written, was standing alone against Germany. To investigate its potential, a committee was created. It reported in 1941 that a bomb was not only feasible, but that it was imperative that Britain develop one and that co-operation with the United States was crucial. From 1941 onwards, under the code name ‘Tube Alloys’, Britain began to research how to build a nuclear weapon. With American collaboration assured in 1943, Britain decided to relocate its scientists to help resolve the scientific issues hindering US progress.
The Manhattan Project (to build the first atomic bomb) had its heart at Los Alamos in the New Mexico desert. British scientists and technicians worked at a number of sites spread across the breadth of the US, but most were based at Los Alamos, which included a significant number of European émigrés in its top positions, people who had escaped Nazism.
The British mission arrived in December 1943 and by the following year comprised just 19 people: a tiny fraction of the estimated 3,500 total population of Los Alamos. The numbers concealed the value and importance of the British contingent. British scientists were at the heart of some of the most important scientific work. Hans Bethe, who was head of the Theoretical Division, later stated that “the collaboration of the British mission was absolutely essential… without the members of the British mission, it is not unlikely that our final weapon would have been considerably less efficient in this case”.
On 16 July 1945 in the Alamogordo desert, the first ever atomic device – Trinity – was exploded. Within a few weeks two different types of bomb – one plutonium implosion; the other uranium gun-method – were dropped on Japan. With the subsequent end of the war, the wives of the British mission prepared a formal party to celebrate, complete with a “feast” of soup, steak and kidney pie and trifle.
A farsighted move
Despite the end of the war, work continued at Los Alamos. The majority of the British mission had left, although some notable figures – including Klaus Fuchs, who would later be revealed as a Soviet spy – remained until 1946. The head of the British mission, Sir James Chadwick (who had won a Nobel prize for discovering the neutron) ordered all departing members to take note of their and other people’s research before leaving the US. The result was an encyclopaedia of the work done during the war. This proved to be a prescient move – in 1946 the US Congress passed the Atomic Energy Act (known as the McMahon Act) which forbade the passing of technical information to any third party, including the UK.
War had devastated Britain and it emerged from the six-year conflict economically ruined. The new prime minister, Clement Attlee, was quick to grasp the potential for nuclear weapons. In late August 1945 he wrote that “a decision on major policy with regard to the atomic bomb is imperative”, and that until it was taken, all postwar planning would be “worthless”. That decision was formally taken in January 1947 in a specially restricted cabinet committee yet, in practice, the wheels had been set in motion long before this.
Why did Britain need an atomic capability? Several factors were important: the British assumed that the Soviet Union would acquire them; the best means of defence against nuclear weapons was to have nuclear weapons; there was no international agreement on their use; and it allowed Britain to remain at the high table of international politics, particularly vis-à-vis the Americans.
The foreign secretary, Ernest Bevin, is famously said to have commented at a cabinet meeting that “we’ve got to have this. I don’t mind for myself, but I don’t want any other foreign secretary of this country to be talked at, or to, by the secretary of state of the United States as I just have had… we’ve got to have this thing over here, whatever it costs… we’ve got to have a bloody Union Jack flying on top of it.”
William Penney, who had been part of the British mission to Los Alamos, was chosen to be in charge of the scientific aspects. The design for the bomb was to replicate the device dropped on Nagasaki, and Penney is said to have compared scientific advances with what was known from Chadwick’s encyclopaedia of the wartime efforts.
Work continued in great secrecy throughout the late 1940s and early 1950s. Progress was slow, and there were a number of problems along the way. Even with a good grasp of the science involved, the technical advances necessary were immense, ranging from the construction of incredibly precise machine tooling to the fabrication of fissionable plutonium. Furthermore, the British design was not an exact duplication, and novel approaches had to be made to certain aspects.
As the design of the bomb continued, discussion raged about where to test the device and in what way it should be detonated. An answer to the second question arrived in July 1950: an intelligence assessment concluded that Britain’s great vulnerability lay in its ports. For this reason the British authorities decided to replicate a nuclear explosion in a harbour by detonating the bomb in the hull of a ship.
The answer to the first question – where? – was resolved soon after, when Attlee wrote to Robert Menzies, his Australian counterpart, requesting permission for the bomb to be tested on Australian soil. (The British chose Australia for a number of reasons – including the fact that the government could pay Australia in pounds sterling, not US dollars). Without discussing it with his cabinet colleagues, Menzies – who declared himself “British to the bootstraps” – agreed.
Operation Hurricane was a success. The device worked as hoped and Britain entered the nuclear club as its third member (after the USA and Soviet Union). Scientifically, it was a great achievement, particularly for a country that had been so ravaged by war.
However, the radioactive fallout from the test turned out to be greater than predicted and was subsequently detected – at very low doses – at locations thousands of miles away. Part of the explanation for this was what had prompted the test: detonation of a bomb onboard a ship in a harbour setting. Despite this, a 1985 official Australian inquiry concluded that operational policies had been followed and that there had been no exposure above prescribed radiation limits.
Within a month the British test was eclipsed by an American one. On 1 November on an atoll in the Pacific, the Americans exploded a device that employed thermonuclear reactions. This ‘hydrogen bomb’ produced a yield over 400 times greater than the British test. The arms race had truly begun.
Nuclear Britain: What happened after 1952?
The test of an atomic bomb in 1952 was the beginning, not the end, of Britain’s involvement in nuclear weapons. Even while scientists had been working on the atomic bomb, advanced atomic designs were being discussed, as were ideas for a hydrogen bomb. The technical leap from atomic to hydrogen weapons was as great as the jump to the first bomb. The increase in potency was significant: scientifically there is no upper limit to the destructive yield of a hydrogen bomb.