Nuclear weapons tests are experiments carried out to determine the performance, yield , and effects of nuclear weapons . Testing nuclear weapons offers practical information about how the weapons function, how detonations are affected by different conditions, and how personnel, structures, and equipment are affected when subjected to nuclear explosions . However, nuclear testing has often been used as an indicator of scientific and military strength. Many tests have been overtly political in their intention; most nuclear weapons states publicly declared their nuclear status through a nuclear test.
186-794: Operation Mosaic was a series of two British nuclear tests conducted in the Montebello Islands in Western Australia on 16 May and 19 June 1956. These tests followed the Operation Totem series and preceded the Operation Buffalo series. The second test in the series was the largest ever conducted in Australia. The purpose of the tests was to explore increasing the yield of British nuclear weapons through boosting with lithium-6 and deuterium , and
372-465: A British hydrogen bomb, 15 July was set as the terminal date for Operation Mosaic. The British Government was anxious that Grapple should take place before a proposed moratorium on nuclear testing came into effect. The second test was therefore conducted under time pressure. At the time of the Royal Commission into British nuclear tests in Australia it was claimed that the second test was of
558-733: A Montebello Working Party as a subcommittee of the Maralinga Committee as a counterpart to the British Mosex. Adams met with W. A. S. Butement of the recently formed Atomic Weapons Tests Safety Committee (AWTSC), an organisation created by the Australian Government to oversee the safety of nuclear tests. Mosex agreed that at least two members of the AWTSC would be present on board the Task Force 308 flagship,
744-681: A combined American, British, and Canadian project. The British Government expected that the United States would continue to share nuclear technology after the war, which it regarded as a joint discovery, but the United States Atomic Energy Act of 1946 (McMahon Act) ended technical cooperation. Fearing a resurgence of United States isolationism , and Britain losing its great power status, the British Government restarted its own development effort, which
930-427: A design incorporating staging, radiation implosion, and compression, but they had not mastered the design of thermonuclear weapons. Knowing that much of the yield of American and Soviet bombs came from fission in the uranium-238 tamper , they had focused on what they called the "lithium-uranium cycle", whereby neutrons from the fission of uranium would trigger fusion, which would produce more neutrons to induce fission in
1116-495: A distrust of British security arrangements. The remaining British scientists working in the United States were denied access to papers that they had written just days before. Attlee set up a cabinet sub-committee , the Gen 75 Committee (known informally by Attlee as the "Atomic Bomb Committee"), on 10 August 1945 to examine the feasibility of an independent British nuclear weapons programme. The Chiefs of Staff Committee considered
1302-462: A fission bomb. It would produce radiation to implode a secondary, Dick, another fission device. In turn, it would implode Harry, a thermonuclear tertiary. Henceforth, the British designers would refer to Tom, Dick and Harry rather than primary, secondary and tertiary. They still had only vague ideas about how a thermonuclear weapon would work, and whether one, two, or three stages would be required. Nor
1488-481: A flabbergasted Oulton. "We shall have to do it all again, providing we can do so before the ban comes into force; so that means as soon as possible." A re-think was required. Cook had the unenviable task of explaining the failure to the government. Henceforth, he would take a tighter grip on the hydrogen bomb programme, gradually superseding Penney. The scientists and politicians considered abandoning Green Granite. The Minister of Defence, Duncan Sandys , queried Cook on
1674-497: A given weapon type for a country is included, as well as tests that were otherwise notable (such as the largest test ever). All yields (explosive power) are given in their estimated energy equivalents in kilotons of TNT (see TNT equivalent ). Putative tests (like Vela incident ) have not been included. British hydrogen bomb programme The British hydrogen bomb programme was the ultimately successful British effort to develop hydrogen bombs between 1952 and 1958. During
1860-504: A hydrogen bomb, but produced three designs: Orange Herald , a large boosted fission weapon ; Green Bamboo , an interim thermonuclear design; and Green Granite , a true thermonuclear design. The first series of Operation Grapple tests involved Britain's first airdrop of a thermonuclear bomb. Although hailed as a success at the time, the first test of the Green Granite design was a failure. The second test validated Orange Herald as
2046-487: A hydrographic survey of the Montebello Islands, laying marker buoys for moorings. Care had to be taken with this, as Operation Hurricane had left some parts of the islands dangerously radioactive. The corvettes HMAS Fremantle and HMAS Junee provided logistical support, ferried personnel between the islands and the mainland, and accommodated 14 Australian and British media representatives during
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#17327945686382232-701: A joint discovery, but the United States Atomic Energy Act of 1946 (also known as the McMahon Act) ended technical cooperation. Fearing a resurgence of American isolationism, and the loss of Britain's great power status, the British government resumed its own development effort, which was codenamed " High Explosive Research ". The successful nuclear test of a British atomic bomb in Operation Hurricane in October 1952 represented an extraordinary scientific and technological achievement. Britain became
2418-655: A joint discovery. On 8 August 1945 the Prime Minister, Clement Attlee , sent a message to President Harry Truman in which he referred to both of them as "heads of the Governments which have control of this great force". On 9 November 1945, Attlee and the Prime Minister of Canada , Mackenzie King , went to Washington, D.C., to confer with Truman about future cooperation in nuclear weapons and nuclear power. A Memorandum of Intention they signed replaced
2604-429: A larger radiation case. The safety limit was again set to 2 megatonnes of TNT (8.4 PJ). Keith Roberts calculated that the yield could reach 3 megatonnes of TNT (13 PJ), and suggested that this could be reduced by modifying the tamper, but Cook opposed this, fearing that it might cause the test to fail. Because of the possibility of a moratorium on testing, plans for the test, codenamed Grapple Y, were restricted to
2790-415: A location continued, with Malden Island and McKean Island being considered. The former became the frontrunner. Three Avro Shackletons from No. 240 Squadron RAF were sent to conduct an aerial reconnaissance and Holland agreed to send the survey ship HMNZS Lachlan to conduct a maritime survey. The test series was given the secret codename "Operation Grapple". Air Commodore Wilfrid Oulton
2976-426: A major construction effort to improve the facilities on Christmas Island, and those that had been constructed on Malden Island had to now be duplicated on Christmas Island. Works included 26 blast-proof shelters, a control room, and tented accommodation. Components of Rounds A and C were delivered to Christmas Island on 24, 27 and 29 October. Round B would not be available; to get the calculations for Round A completed,
3162-471: A mastery of thermonuclear weapons technology. An international moratorium on nuclear tests commenced on 31 October 1958, and Britain ceased atmospheric testing for good. The successful development of the hydrogen bomb, along with the Sputnik crisis , resulted in the 1958 US–UK Mutual Defence Agreement , in which the nuclear Special Relationship was restored. The neutron was discovered by James Chadwick at
3348-606: A matter of urgency. A new directorate known as Tube Alloys was created to coordinate this effort. Sir John Anderson , the Lord President of the Council , became the minister responsible, and Wallace Akers from Imperial Chemical Industries (ICI) was appointed the director of Tube Alloys. In July 1940, Britain offered the United States access to its scientific research, and Cockcroft briefed American scientists on British nuclear weapons developments. He discovered that
3534-530: A moratorium would restrict further nuclear weapons development by the Soviet Union; but it would also lock the United Kingdom into a permanent state of inferiority. The Defence Policy Committee, chaired by the Prime Minister and consisting of the senior Cabinet members, considered the political and strategic implications on 1 June, and concluded that "we must maintain and strengthen our position as
3720-506: A number of populated islands in nearby atoll formations. Though they were soon evacuated, many of the islands' inhabitants suffered from radiation burns and later from other effects such as increased cancer rate and birth defects, as did the crew of the Japanese fishing boat Daigo Fukuryū Maru . One crewman died from radiation sickness after returning to port, and it was feared that the radioactive fish they had been carrying had made it into
3906-475: A paper in which he described the mechanism of thermonuclear burning. He suggested that the Americans had compressed lithium-6 and uranium around a fissile core. In April 1956, the recognisable ancestor of the later devices appeared. There were now only two stages: Tom, the fission primary; and Dick, which was now also a set of concentric spheres, with uranium-235 and lithium-6 deuteride shells. A spherical Dick
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#17327945686384092-607: A patent in May 1946. This was tested in the American Operation Greenhouse George test in May 1951, but was also found to be unworkable. There was also some intelligence about Joe 4 derived from its debris, which was provided to Britain under the 1948 Modus Vivendi . Penney established three megaton bomb projects at Aldermaston: Orange Herald , under Bryan Taylor , a large boosted fission weapon; Green Bamboo , an interim thermonuclear design similar to
4278-493: A plutonium processing plant at Windscale , and a gaseous diffusion uranium enrichment facility at Capenhurst , near Chester . Uranium ore was stockpiled at Springfields. As the American nuclear programme expanded, its requirements became greater than the production of the existing mines. To gain access to the stockpile, they reopened negotiations, which resulted in the 1948 Modus Vivendi , which allowed for consultation on
4464-487: A prohibited area until 1992. A 2006 zoological survey found that the wildlife had recovered. As part of the Gorgon gas project , rats and feral cats were eradicated from the Montebello Islands in 2009, and birds and marsupials were transplanted from nearby Barrow Island to Hermite Island. Today, the Montebello Islands are a park. Visitors are advised not to spend more than an hour per day at the test sites, or to take relics of
4650-532: A result of a scenario of a concentrated number of nuclear explosions in a nuclear holocaust , the thousands of tests, hundreds being atmospheric, did nevertheless produce a global fallout that has peaked in 1963 (the Bomb pulse ), reaching levels of about 0.15 mSv per year worldwide, or about 7% of average background radiation dose from all sources, and has slowly decreased since, with natural environmental radiation levels being around 1 mSv . This global fallout
4836-687: A series of meetings in Washington, DC, on 27 and 28 August 1958 to work out the details. The U.S. delegation included Willard Libby , AEC deputy chairman; Major General Herbert Loper , the Assistant to the Secretary of Defence for Atomic Energy Affairs; Brigadier General Alfred Starbird , AEC Director of Military Applications; Norris Bradbury , director of the Los Alamos National Laboratory ; Edward Teller , director of
5022-547: A significantly higher yield than suggested by the official figures: 98 kilotonnes of TNT (410 TJ ) as compared to 60 kilotonnes of TNT (250 TJ), but this remains unsubstantiated. During the early part of the Second World War , Britain had a nuclear weapons project, code-named Tube Alloys , which the 1943 Quebec Agreement merged with the American Manhattan Project to create
5208-473: A single salvo test; Pakistan's second and last official test exploded four different devices. Almost all lists in the literature are lists of tests; in the lists in Misplaced Pages (for example, Operation Cresset has separate items for Cremino and Caerphilly , which together constitute a single test), the lists are of explosions. Separately from these designations, nuclear tests are also often categorized by
5394-525: A small committee be established to examine the matter. Cabinet agreed at a meeting in November 1952, and the committee was created, chaired by Crookshank. Cabinet accepted its recommendations in April 1953, and another committee was established under Anderson (now Lord Waverley) to make recommendations on the implementation of the new organisation and its structure. The Atomic Energy Authority Act 1954 created
5580-451: A type of nuclear device in which isotopes of light elements such as lithium-6 and deuterium are added. The resulting nuclear fusion reactions produce neutrons, and thus increase the rate of fission, and therefore the yield . The British had no practical experience with boosting, so a test of the concept was required. The scientists had also heard a rumour from American sources that the yield could be improved by up to 50 per cent through
5766-496: A usable design of a megaton weapon, but it was not a thermonuclear bomb, and the core boosting did not work. A third test attempted to correct the Green Granite design, but was another failure. In the Grapple X test in November 1957, they successfully tested a thermonuclear design. The Grapple Y test the following April obtained most of its yield from nuclear fusion , and the Grapple Z test series later that year demonstrated
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5952-447: A variety of fissile material compositions, densities, shapes, and reflectors . They can be subcritical or supercritical, in which case significant radiation fluxes can be produced. This type of test has resulted in several criticality accidents . Subcritical (or cold) tests are any type of tests involving nuclear materials and possibly high explosives (like those mentioned above) that purposely result in no yield . The name refers to
6138-532: A world power so that Her Majesty's Government can exercise a powerful influence in the counsels of the world." Churchill informed Cabinet of the decision on 7 July 1954, and they were not happy about not being consulted, particularly the Lord Privy Seal , Harry Crookshank . Cabinet debated the matter that day and the next, before postponing a final decision. On 27 July 1954, the Lord President of
6324-531: A yield of 60 kilotonnes of TNT (250 TJ), making it the largest nuclear device ever detonated in Australia. At the time of the Royal Commission into British nuclear tests in Australia in 1985, Joan Smith , a British investigative journalist, published a book, Clouds of Deceit: Deadly Legacy of Britain's Bomb Tests , in which she alleged that the G2 test had a significantly higher yield than suggested by available figures—98 kilotonnes of TNT (410 TJ) as compared to
6510-472: Is effective or not until it has been tested." Testing of boosted designs was carried out by Operation Mosaic in the Monte Bello Islands in Western Australia in May and June 1956. This was a sensitive matter; there was an agreement with Australia that no thermonuclear testing would be carried out there. The Australian Minister for Supply Howard Beale , responding to rumours reported in
6696-488: Is very unlikely to develop significant nuclear innovations without testing. One other approach is to use supercomputers to conduct "virtual" testing, but codes need to be validated against test data. There have been many attempts to limit the number and size of nuclear tests; the most far-reaching is the Comprehensive Test Ban Treaty of 1996, which has not, as of 2013 , been ratified by eight of
6882-658: The Cavendish Laboratory at the University of Cambridge in February 1932, and in April 1932, his Cavendish colleagues John Cockcroft and Ernest Walton split lithium atoms with accelerated protons . In December 1938, Otto Hahn and Fritz Strassmann at Hahn's laboratory in Berlin-Dahlem bombarded uranium with slow neutrons, and discovered that barium had been produced, and therefore that
7068-507: The Kermadec Islands , which lie about 1,000 kilometres (620 mi) northeast of New Zealand, would be suitable. They were part of New Zealand, so Eden wrote to the Prime Minister of New Zealand , Sidney Holland , to ask for permission to use the islands. Holland refused, fearing an adverse public reaction in forthcoming elections. Despite reassurances and pressure from the British government, Holland remained firm. The search for
7254-666: The Landing Ship, Tank , HMS Narvik , when the decision to fire was taken. He also had discussions with Leonard Dwyer, the Director of the Australian Bureau of Meteorology about the weather conditions that could be expected for the test. It was agreed that a Royal Australian Navy (RAN) frigate would act as a weather ship for the test series, and that a second weather ship might be required to give warnings of willy willys and cyclones . A small fleet of ships
7440-694: The Lawrence Livermore Laboratory ; and James W. McCrae, president of the Sandia Corporation . The British representatives were Brundrett and J.H.B. Macklen from the Ministry of Defence, and Penney, Cook and E. F. Newly from Aldermaston. The Americans disclosed the details of nine of their nuclear weapon designs: the Mark 7 , Mark 15 / 39 , Mark 19 , Mark 25 , Mark 27 , Mark 28 , Mark 31 , Mark 33 and Mark 34 . In return,
7626-620: The Operation Buffalo tests were already scheduled to be held there. It was therefore decided that the best option was to return to the Montebello Islands, where the operation could be supported by the Royal Navy . There were also doubts as to whether the Australian Government would allow a 50-kilotonne-of-TNT (210 TJ) test at Maralinga. This was a sensitive matter; there was an agreement with Australia that no thermonuclear testing would be carried out there. The Australian minister for supply , Howard Beale , responding to rumours reported in
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7812-668: The Pilbara region, although four Royal Air Force (RAF) Shackletons and about 70 RAF personnel were based at RAAF Base Darwin , from whence the Shackletons daily flew weather reconnaissance flights, commencing on 2 March. There was a cyclone three days later. Three Royal Australian Air Force (RAAF) Neptunes flew safety patrols, five RAF Varsity aircraft tracked clouds and flew on low-level radiological survey missions, five RAF Canberra bombers were tasked with collecting radioactive samples, four RAF Hastings aircraft flew between
7998-903: The Quebec Conference in August 1943, the Prime Minister , Winston Churchill , and the President of the United States , Franklin Roosevelt , signed the Quebec Agreement , which merged the two national projects. The Quebec Agreement established the Combined Policy Committee and the Combined Development Trust to coordinate their efforts. The 19 September 1944 Hyde Park Agreement extended both commercial and military cooperation into
8184-697: The United Kingdom Atomic Energy Authority (UKAEA) on 19 July 1954. Plowden became its first chairman. His fellow board members were Hinton, who was in charge of the Industrial Group at Risley; Cockcroft, who headed the Research Group at Harwell; and Penney, who led the Weapons Group at Aldermaston. The UKAEA initially reported to Salisbury in his capacity as Lord President of the Council; later in
8370-691: The V-bombers , or on missiles. Sandys was not convinced, but he authorised further tests, as did the Prime Minister, now Harold Macmillan following Eden's resignation in the wake of the Suez crisis . The earliest possible date was November 1957 unless the Operation Antler tests were cancelled, but the Foreign Office warned that a moratorium on nuclear testing might come into effect in late October. The scientists at Aldermaston had created
8556-524: The Vela incident . From the first nuclear test in 1945 until tests by Pakistan in 1998, there was never a period of more than 22 months with no nuclear testing. June 1998 to October 2006 was the longest period since 1945 with no acknowledged nuclear tests. A summary table of all the nuclear testing that has happened since 1945 is here: Worldwide nuclear testing counts and summary . While nuclear weapons testing did not produce scenarios like nuclear winter as
8742-421: The critical mass of a metallic sphere of pure uranium-235 , and found that instead of tons, as everyone had assumed, as little as 1 to 10 kilograms (2.2 to 22.0 lb) would suffice, and would explode with the power of thousands of tons of dynamite. The MAUD Committee was established to investigate further. It reported that an atomic bomb was technically feasible, and recommended pursuing its development as
8928-580: The prime minister of Australia , Robert Menzies , on 16 May 1955. Eden detailed the nature and purpose of the tests. He explained that the experiments would include the addition of light elements as a boost, but promised that the yield of neither test would exceed two and a half times that of the Operation Hurricane test. Neither the anticipated nor the actual yield of the Hurricane test had been officially disclosed to Australian officials, but
9114-558: The tanker RFA Eddyrock , they formed Task Group 308.1. The Far East Fleet also supplied the cruiser HMS Newfoundland , and destroyers HMS Cossack , Concord , Consort and Comus . These formed Task Group 308.3, which was mainly responsible for weather reporting. The destroyer HMS Diana was detailed to carry out scientific tests, and formed Task Group 308.4. They were augmented by RAN vessels, designated Task Group 308.2. The sloop HMAS Warrego and boom defence vessel Karangi carried out
9300-474: The " Annex 2 countries " required for it to take effect, including the United States. Nuclear testing has since become a controversial issue in the United States, with a number of politicians saying that future testing might be necessary to maintain the aging warheads from the Cold War . Because nuclear testing is seen as furthering nuclear arms development, many are opposed to future testing as an acceleration of
9486-632: The 23 crewmen of a Japanese fishing boat, the Daigo Fukuryū Maru ( Lucky Dragon No. 5 ). Meanwhile, the Soviet Union tested Joe 4 , a boosted fission weapon with a yield of 400 kilotonnes of TNT (1,700 TJ) on 12 August 1953. This was followed by Joe 19 , a true two-stage thermonuclear weapon on 20 November 1954. Although the British Hurricane device was more advanced than the American Fat Man bombs of 1946, Britain
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#17327945686389672-675: The Admiralty to be Penney's deputy. Cook commenced work at Aldermaston on 1 September 1954. Henry Hulme joined in 1954. He was too senior to be placed in Corner's theoretical physics division, so he became an assistant to Penney, with special responsibility for the hydrogen bomb programme. Samuel Curran, who had worked on the Manhattan Project in Berkeley, became head of the radiation measurements division. The physicist John Ward
9858-604: The American S-1 Project (later renamed the Manhattan Project ) was smaller than the British, and not as far advanced. The two projects exchanged information, but did not initially combine their efforts, ostensibly over concerns about American security. Ironically, it was the British project that had already been penetrated by atomic spies for the Soviet Union . The United Kingdom did not have
10044-436: The British government wanted. Churchill, who had replaced Attlee as prime minister, turned to Lord Cherwell for advice on the prospect of producing a British hydrogen bomb. Cherwell reported that "We think we know how to make an H-bomb", but Penney did not agree with this sanguine assessment. A New Weapons Committee was established at Aldermaston on 15 October 1951 to examine improvements to their atomic bombs. John Corner ,
10230-488: The British provided the details of seven of theirs, including Green Grass; Pennant, the boosted device which had been detonated in the Grapple Z test on 22 August; Flagpole, the two-stage device scheduled for 2 September; Burgee, scheduled for 23 September; and the three-stage Haillard 3. The Americans were impressed with the British designs, particularly with Haillard 1, the heavier version of Haillard 3. Cook therefore changed
10416-539: The CTBT has been signed by 183 States, of which 157 have also ratified. However, for the Treaty to enter into force it needs to be ratified by 44 specific nuclear technology-holder countries. These "Annex 2 States" participated in the negotiations on the CTBT between 1994 and 1996 and possessed nuclear power or research reactors at that time. The ratification of eight Annex 2 states is still missing: China, Egypt, Iran, Israel and
10602-488: The Council, the Marquess of Salisbury , raised the matter, although it was not on the agenda, stressing the need for a decision. This time Cabinet agreed to proceed with the development of thermonuclear weapons. Churchill's return to the prime ministership meant Lord Cherwell's return to the post of Paymaster General . He was a strong supporter of the atomic energy programme, but while he agreed with its size and scope, he
10788-547: The Grapple Z programme to fire Haillard 1 instead of Haillard 3. Macmillan wrote to Plowden: I had a very interesting talk with Brundrett, Penney and Cook about their discussions in Washington last week, and I have been very impressed by the results which they have achieved. It is clear that the Americans were amazed to learn how much we already know and this was a major factor in convincing them that we could be trusted with more information than they probably intended originally to give us. I hope that these discussions will be only
10974-493: The Green Granite test and substituted a new weapon codenamed Purple Granite. This was identical to Short Granite, but with some minor modification to it; additional uranium-235 was added, and the outer layer was replaced with aluminium. Despite its failure, the test was described as a successful thermonuclear explosion, and the government did not confirm or deny reports that the UK had become a third thermonuclear power. When documents on
11160-403: The House of Commons on 5 April 1954 in which Churchill blamed Attlee for the McMahon Act. The new Eisenhower administration in the United States looked favourably on the idea of a moratorium, and the Foreign Secretary , Anthony Eden , was sounded out about it by the U.S. Secretary of State, John Foster Dulles . The United States had now finished its Operation Castle series of tests, and such
11346-441: The IBM 704 had to be turned over to them, and there was no possibility of completing the Round B calculations on the Ferranti. On inspection, a fault was found in the Round A Tom, and the fissile core was replaced with the one from Round C. Round A was dropped by a Valiant bomber piloted by Squadron Leader Barney Millett at 08:47 on 8 November 1957. This time the yield of 1.8 megatonnes of TNT (7.5 PJ) exceeded expectations;
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#173279456863811532-525: The Japanese food supply. Castle Bravo was the worst U.S. nuclear accident, but many of its component problems—unpredictably large yields, changing weather patterns, unexpected fallout contamination of populations and the food supply—occurred during other atmospheric nuclear weapons tests by other countries as well. Concerns over worldwide fallout rates eventually led to the Partial Test Ban Treaty in 1963, which limited signatories to underground testing. Not all countries stopped atmospheric testing, but because
11718-432: The Mosaic Executive (Mosex) or Buffalo Executive (Buffalex) as appropriate. Captain Hugh Martell would be in charge as commander Task Force 308, with the temporary rank of commodore . Charles Adams from Aldermaston, who had been the deputy technical director to Leonard Tyte for Operation Hurricane and to William Penney on Operation Totem, was appointed the scientific director for Operation Mosaic, with Ieuan Maddock as
11904-428: The Partial Nuclear Test Ban Treaty. The 1996 Comprehensive Nuclear-Test-Ban Treaty (CTBT) bans all nuclear explosions everywhere, including underground. For that purpose, the Preparatory Commission of the Comprehensive Nuclear-Test-Ban Treaty Organization is building an international monitoring system with 337 facilities located all over the globe. 85% of these facilities are already operational. As of May 2012 ,
12090-399: The Parting Pool in the Montebello Islands. The Radiological Group, wearing full protective clothing, entered the lagoon in a cutter . They retrieved measuring instruments and conducted a ground survey. A tent with a decontamination area was established ashore, and a water pump allowed the Radiological Group to wash themselves before they returned to Narvik . The main danger to the ships' crews
12276-483: The Pendant and Burgee tests, allowing a smaller, lighter Tom for two-stage devices. The international moratorium commenced on 31 October 1958, and Britain ceased atmospheric testing for good. British timing was good. The Soviet Union's launch of Sputnik 1 , the world's first artificial satellite , on 4 October 1957, came as a tremendous shock to the American public, who had trusted that American technological superiority ensured their invulnerability. Now, suddenly, there
12462-429: The Prime Minister, who gave verbal approval, and a handful of officials. Air Vice Marshal John Grandy succeeded Oulton as Task Force commander. The bomb was dropped off Christmas at 10:05 local time on 28 April 1958 by a Valiant piloted by Squadron Leader Bob Bates. It had an explosive yield of about 3 megatonnes of TNT (13 PJ), and remains the largest British nuclear weapon ever tested. The design of Grapple Y
12648-420: The Quebec Agreement. The three leaders agreed that there would be full and effective cooperation on atomic energy, but British hopes were soon disappointed. The Atomic Energy Act of 1946 (McMahon Act), which was signed into law by Truman on 1 August 1946, ended technical cooperation. Its control of "restricted data" prevented the United States' allies from receiving any information. This partly resulted from
12834-435: The RAF had reckoned that fission bombs would be sufficient for most targets, and therefore that Britain had no intention of developing hydrogen bombs. On 12 and 19 March 1954, Penney briefed the Gen 475 Committee meetings, attended by the Chiefs of Staff, senior officials from the Ministry of Defence and Foreign Office , and Sir Edwin Plowden , about recent developments in thermonuclear weapons. Sir Frederick Brundrett ,
13020-402: The Soviet Layer Cake used in Joe 4 and the American Alarm Clock; and Green Granite , a true thermonuclear design. Orange Herald would be the first British weapon to incorporate an external neutron initiator . For Green Granite, Penney proposed a design based on radiation implosion and staging. There would be three stages, which he called Tom, Dick and Harry. Tom, the primary stage, would be
13206-509: The Treasury refused to adjust the salaries of his other two deputies to match. Rather than ruin his organisation's morale, Hinton had dropped the proposal to appoint Kearton. Nor could any reorganisation be carried out without Treasury approval. Within a month of assuming office, Cherwell had prepared a memorandum proposing that responsibility for the program be transferred from the Ministry of Supply to an Atomic Energy Commission. Cherwell managed to persuade Churchill to propose to Cabinet that
13392-470: The UK and Australia, and two Whirlwind helicopters provided a taxi service. The United States Air Force (USAF) provided a pair of C-118 Liftmasters to collect radioactive samples. Lieutenant-Colonel R. N. B. Holmes was in charge of the Royal Engineers, whose task including erecting the 300-foot (91 m) aluminium towers for the shots. Adams arrived at the Montebello Islands on 22 April, and
13578-425: The UK and refit for Operation Grapple , the first test of a British hydrogen bomb, 15 July was set as the terminal date for Mosaic. As the deadline approached, William Cook , the scientist in charge of the hydrogen bomb project at Aldermaston, determined that in view of the results of G1, G2 was now more important than ever. He agreed that, if necessary, Grapple, could be delayed to conduct G2. With time running short,
13764-891: The United Kingdom until 1991, the United States until 1992, and both China and France until 1996. In signing the Comprehensive Nuclear-Test-Ban Treaty in 1996, these countries pledged to discontinue all nuclear testing; the treaty has not yet entered into force because of its failure to be ratified by eight countries. Non-signatories India and Pakistan last tested nuclear weapons in 1998. North Korea conducted nuclear tests in 2006 , 2009 , 2013 , January 2016 , September 2016 and 2017. The most recent confirmed nuclear test occurred in September 2017 in North Korea. Nuclear weapons tests have historically been divided into four categories reflecting
13950-561: The United States and the Soviet Union were responsible for roughly 86% of all nuclear tests, their compliance cut the overall level substantially. France continued atmospheric testing until 1974, and China until 1980. A tacit moratorium on testing was in effect from 1958 to 1961 and ended with a series of Soviet tests in late 1961, including the Tsar Bomba , the largest nuclear weapon ever tested. The United States responded in 1962 with Operation Dominic , involving dozens of tests, including
14136-457: The United States have signed but not ratified the Treaty; India, North Korea and Pakistan have not signed it. The following is a list of the treaties applicable to nuclear testing: Over 500 atmospheric nuclear weapons tests were conducted at various sites around the world from 1945 to 1980. As public awareness and concern mounted over the possible health hazards associated with exposure to the nuclear fallout , various studies were done to assess
14322-409: The amount of it that is necessary. Hydronuclear tests study nuclear materials under the conditions of explosive shock compression. They can create subcritical conditions, or supercritical conditions with yields ranging from negligible all the way up to a substantial fraction of full weapon yield. Critical mass experiments determine the quantity of fissile material required for criticality with
14508-417: The arms race. In total nuclear test megatonnage , from 1945 to 1992, 520 atmospheric nuclear explosions (including eight underwater) were conducted with a total yield of 545 megatons , with a peak occurring in 1961–1962, when 340 megatons were detonated in the atmosphere by the United States and Soviet Union , while the estimated number of underground nuclear tests conducted in the period from 1957 to 1992
14694-688: The arrest for espionage of British physicist Alan Nunn May , who had worked in the Montreal Laboratory, in February 1946, while the legislation was being debated. It was but the first of a series of spy scandals. The arrest of Klaus Fuchs in January 1950, and the June 1951 defection of Donald Maclean , who had served as a British member of the Combined Policy Committee from January 1947 to August 1948, left Americans with
14880-479: The assembly, wanted to know the configuration of Green Granite. Cook ruled that it would use a Red Beard Tom, and would fit inside a Blue Danube casing for dropping. The design was frozen in April 1956. There were two versions of Orange Herald, large and small. They had similar cores, but the large version contained more explosive. The designs were frozen in July. Green Bamboo was also nominally frozen, but tinkering with
15066-482: The burial points of all explosive devices can be connected by segments of straight lines, each of them connecting two burial points, and the total length does not exceed 40 kilometers. For nuclear weapon tests, a salvo is defined as two or more underground nuclear explosions conducted at a test site within an area delineated by a circle having a diameter of two kilometers and conducted within a total period of time of 0.1 seconds. The USSR has exploded up to eight devices in
15252-685: The chairman of the Chiefs of Staff's Working Party on the Operational Use of Atomic Weapons (OAW), then asked Penney on 25 May for a working paper for an OAW meeting on 31 May. In turn, OAW sent a report to the Chiefs of Staff, who recommended that the United Kingdom develop its own thermonuclear weapons. Admiral of the Fleet Sir Rhoderick McGrigor , the First Sea Lord , recalled that: The United Kingdom, as
15438-527: The cloud had trouble finding it, and only after some searching located it about 80 miles (130 km) from where it was supposed to be. The following day, the Canberra sent to track the cloud and collect more samples could not locate it at all. The bulk of the fallout drifted over the Arafura Sea , but owing to different winds at different altitudes, part of it again drifted over the mainland. As fallout
15624-416: The cloud to collect samples, one of which was flown by Menaul. The results of the test were mixed. The yield was between 15 and 20 kilotonnes of TNT (63 and 84 TJ), as had been anticipated, although the mushroom cloud rose to 21,000 feet (6,400 m) instead of 14,000 feet (4,300 m) as predicted. Valuable data was obtained. The implosion system had performed flawlessly, but the boosting effect of
15810-560: The construction effort alone. The tank landing ship HMS Narvik would reprise the role of control ship it had for Operation Hurricane; but as it was also required for Operation Mosaic, it had very little time to return to the Chatham Dockyard for a refit before heading out to Christmas Island for Operation Grapple. Having decided on a location and date, there still remained the matter of what would be tested. John Challens , whose weapons electronics group would have to produce
15996-457: The contamination was highest, would receive a dose of 580 microsieverts (0.058 rem ) over a period of 50 years, assuming that they wore no clothes; an annual exposure of 150 millisieverts (15 rem) is normally considered acceptable for occupational purposes. By the 1980s the radioactivity had decayed to the point where it was no longer hazardous to the casual visitor, but there were still radioactive metal fragments. The island remained
16182-583: The contrary, the United States, the Soviet Union and the United Kingdom all rushed to perform as much testing as possible before the deadline, which the Soviets did not meet, conducting tests on 1 and 3 November. A new British test series, known as Grapple Z, commenced on 22 August. It explored new technologies such as the use of external neutron initiators, which had first been tried out with Orange Herald. Core boosting using tritium gas and external boosting with layers of lithium deuteride were successfully tested in
16368-461: The date for the test. There had been protests in Perth at the test series, and the deputy premier of Western Australia , John Tonkin , promised to discuss demands for an end to the tests. Martin and Titterton confronted Martell and Adams, and Martin told them that without sufficient information about the nature of the tests, the AWTSC could not approve the test. That it had a veto came as a surprise; it
16554-550: The decade the UKAEA would report directly to the Prime Minister. Over 20,000 staff transferred to the UKAEA; by the end of the decade, their numbers had grown to nearly 41,000. Like Hinton, Penney had difficulty recruiting and retaining the highly skilled staff he needed. In particular, he wanted a deputy with a strong scientific background. An approach to Vivian Bowden failed. After Penney repeatedly asked for William Cook , Salisbury managed to persuade McGrigor to release Cook from
16740-518: The design continued. On 3 September, Corner suggested that Green Granite could be made smaller by moving the Tom and Dick closer together. This design became known as Short Granite. By January 1957, with the tests just months away, a tentative schedule had emerged. Short Granite would be fired first. Green Bamboo would follow if Short Granite was unsuccessful, but be omitted as unnecessary otherwise. Orange Herald (small) would be fired next. Because Short Granite
16926-588: The development of thermonuclear weapons would shore up Britain's great power status and restore the special relationship with the United States, which would give the UK a prospect of influencing American defence policy. There was a third political consideration: the Lucky Dragon incident had touched off a storm of protest, and there were calls from trade unions and the Labour Party for a moratorium on nuclear testing, resulting in an acrimonious debate in
17112-492: The early part of the Second World War , Britain had a nuclear weapons project, codenamed Tube Alloys . At the Quebec Conference in August 1943, British prime minister Winston Churchill and United States president Franklin Roosevelt signed the Quebec Agreement , merging Tube Alloys into the American Manhattan Project , in which many of Britain's top scientists participated . The British government trusted that America would share nuclear technology, which it considered to be
17298-719: The explosion of a missile launched from a submarine. Almost all new nuclear powers have announced their possession of nuclear weapons with a nuclear test. The only acknowledged nuclear power that claims never to have conducted a test was South Africa (although see Vela incident ), which has since dismantled all of its weapons. Israel is widely thought to possess a sizable nuclear arsenal, though it has never tested, unless they were involved in Vela. Experts disagree on whether states can have reliable nuclear arsenals—especially ones using advanced warhead designs, such as hydrogen bombs and miniaturized weapons—without testing, though all agree that it
17484-441: The explosion's effects, it did not give an appreciable understanding of nuclear fallout , which was not well understood by the project scientists until well after the atomic bombings of Hiroshima and Nagasaki . The United States conducted six atomic tests before the Soviet Union developed their first atomic bomb ( RDS-1 ) and tested it on August 29, 1949. Neither country had very many atomic weapons to spare at first, and so testing
17670-405: The extent of the hazard. A Centers for Disease Control and Prevention / National Cancer Institute study claims that nuclear fallout might have led to approximately 11,000 excess deaths, most caused by thyroid cancer linked to exposure to iodine-131 . The following list is of milestone nuclear explosions. In addition to the atomic bombings of Hiroshima and Nagasaki , the first nuclear test of
17856-415: The first of a series, in which Anglo-American cooperation in this field will become progressively closer. But if we do succeed in gradually persuading the Americans to regard the enterprise as a joint project in which we are entitled to be regarded as equal partners in terms of basic knowledge, it will be because we have got off to a flying start under the bilateral agreement; and the credit for that must go to
18042-492: The first of a thermonuclear weapon. The United States had not attempted an airdrop of a hydrogen bomb until the Operation Redwing Cherokee test on 21 May 1956. Their bomb had landed 6.4 kilometres (4 mi) from the target; Hubbard missed by just 382 metres (418 yd). The Short Granite's yield was estimated at 300 kilotonnes of TNT (1,300 TJ), far below its designed capability. Penney cancelled
18228-639: The first test. They were replaced by Karangi for the second test. A pair of RAN 120-foot (37 m) motor lighters , MWL251 and MRL252, provided water and refrigeration respectively. The two barges were visited by the First Sea Lord , Admiral Lord Mountbatten , and Lady Mountbatten , who flew out to the islands on a Whirlwind helicopter on 15 April. Only a small party of Royal Engineers and two Aldermaston scientists travelled on Narvik . The main scientific party left London by air on 1 April. The Air Task Group consisted of 107 officers and 407 other ranks. Most were based at Pearce near Perth and Onslow in
18414-497: The formation of these treaties. Examples can be seen in the following articles: The Partial Nuclear Test Ban treaty makes it illegal to detonate any nuclear explosion anywhere except underground, in order to reduce atmospheric fallout. Most countries have signed and ratified the Partial Nuclear Test Ban, which went into effect in October 1963. Of the nuclear states, France, China, and North Korea have never signed
18600-652: The head of the theoretical group at Aldermaston, suggested producing a device in the "megaton range"—one with a yield of 500 kilotonnes of TNT (2,100 TJ) or more. In this he was thinking not of a thermonuclear weapon, but of a large fission one. The idea was not pursued at that time, because the RAF wanted more, not bigger, atomic bombs. Meeting in Bermuda in December 1953 with Dwight D. Eisenhower , who had replaced Truman as president earlier that year, Churchill told him that
18786-415: The imperative to persist with thermonuclear designs, given that Orange Herald satisfied most military requirements, and the tests were very expensive. Cook replied that megaton-range fission bombs represented an uneconomical use of expensive fissile material, that they could not be built to produce yields of more than a megaton, and that they could not be made small enough to be carried by aircraft smaller than
18972-452: The island. The physicists at Aldermaston had plenty of ideas about how to follow up Grapple X. Possibilities were discussed in September 1957. One was to tinker with the width of the shells in the Dick to find an optimal configuration. If they were too thick, they would slow the neutrons generated by the fusion reaction; if they were too thin, they would give rise to Taylor instability. Another
19158-555: The issue of nuclear weapons in July 1946, and recommended that Britain acquire them. A nuclear reactor and plutonium -processing facility was approved by the Gen 75 committee on 18 December 1945 "with the highest urgency and importance". The decision to proceed was formally made on 8 January 1947 at a meeting of Gen 163, another cabinet subcommittee, and was publicly announced in the House of Commons on 12 May 1948. D notice No. 25 forbid
19344-491: The lack of creation of a critical mass of fissile material. They are the only type of tests allowed under the interpretation of the Comprehensive Nuclear-Test-Ban Treaty tacitly agreed to by the major atomic powers. Subcritical tests continue to be performed by the United States, Russia, and the People's Republic of China, at least. Subcritical tests executed by the United States include: The first atomic weapons test
19530-409: The later phases of the Cold War , though, both countries developed accelerated testing programs, testing many hundreds of bombs over the last half of the 20th century. Atomic and nuclear tests can involve many hazards. Some of these were illustrated in the U.S. Castle Bravo test in 1954. The weapon design tested was a new form of hydrogen bomb, and the scientists underestimated how vigorously some of
19716-474: The lithium deuteride had been negligible; the process had not been fully understood. HMS Diana , about 6 miles (9.7 km) from ground zero, was quickly decontaminated, and sailed for Singapore on 18 May. The fallout cloud initially moved out to sea as predicted, but then reversed direction and drifted across northern Australia. Tests on the aircraft at Onslow had detected signs of radioactive contamination from G1, indicating that some fallout had been blown over
19902-457: The mainland. The results of G1 meant that a natural uranium tamper could be used in G2 without exceeding the planned 80 kilotonnes of TNT (330 TJ) limit agreed to with the AWTSC. (One of 100 kilotonnes of TNT (420 TJ) was used for safety purposes.) Scientific rehearsals for G2 were held on 28 and 31 May, followed by a full rehearsal on 4 June. The fissile core for the device was delivered to Onslow by RAF Hastings on 6 June, and once again
20088-452: The manpower or resources of the United States, and despite its early and promising start, Tube Alloys fell behind its American counterpart. The British considered producing an atomic bomb without American help, but it would require overwhelming priority, disruption to other wartime projects was inevitable, and it was unlikely to be ready in time to affect the outcome of the war in Europe . At
20274-455: The medium or location of the test. Another way to classify nuclear tests is by the number of explosions that constitute the test. The treaty definition of a salvo test is: In conformity with treaties between the United States and the Soviet Union, a salvo is defined, for multiple explosions for peaceful purposes, as two or more separate explosions where a period of time between successive individual explosions does not exceed 5 seconds and where
20460-424: The meteorologists predicted a break in the weather and Martell ordered the countdown to recommence. Weather balloons indicated that conditions were stable between 5,000 and 24,500 feet (1,500 and 7,500 m), with an anomaly between 19,000 and 24,500 feet (5,800 and 7,500 m) that was not considered significant. G2 was detonated from a tower on Alpha Island at 02:14 UTC (10:14 local time) on 19 June. It produced
20646-520: The military effects of atomic weapons ( Crossroads had involved the effect of atomic weapons on a navy, and how they functioned underwater) and to test new weapon designs. During the 1950s, these included new hydrogen bomb designs, which were tested in the Pacific, and also new and improved fission weapon designs. The Soviet Union also began testing on a limited scale, primarily in Kazakhstan . During
20832-477: The nature and purpose of the tests. He promised that the yield of the second, larger test would not be more than two and a half times that of the Operation Hurricane test, which was 25 kilotonnes of TNT (100 TJ). Menzies cabled his approval of the tests on 20 June 1955. The yield of the second test turned out to be 60 kilotonnes of TNT (250 TJ), which was larger than the limit of 50 kilotonnes of TNT (210 TJ) for tests in Australia. Another test site
21018-472: The newspapers, asserted that "the Federal Government has no intention of allowing any, hydrogen bomb tests to take place in Australia. Nor has it any intention of allowing any experiments connected with hydrogen bomb tests to take place here." Since the tests were connected with hydrogen bomb development, this prompted Eden to cable the Prime Minister of Australia , Robert Menzies , detailing
21204-436: The newspapers, asserted that "the Federal Government has no intention of allowing any hydrogen bomb tests to take place in Australia. Nor has it any intention of allowing any experiments connected with hydrogen bomb tests to take place here." While a boosted fusion weapon is not a hydrogen bomb, the tests were indeed connected with hydrogen bomb development. The prime minister of the United Kingdom , Sir Anthony Eden , cabled
21390-536: The official figure of 60 kilotonnes of TNT (250 TJ). She based this claim on "secret documents released to the Public Record Office in 1985", but the text was uncited, and the documents have never been found. British official historian Lorna Arnold reported that she had never seen any such documents. The cloud rose to 47,000 feet (14,000 m), considerably higher than the predicted 37,000 feet (11,000 m). The procedure for collecting samples
21576-458: The position is awkward for you and that you must make minor concessions. Rather than stonewall, Adams and Martell disclosed the same information that had been given to Menzies, on condition that they kept it to themselves. This mollified them, and the G1 test went ahead. The device was detonated on Trimouille Island at 03:50 UTC (11:50 local time) on 16 May. Soon afterwards, Narvik and Alert entered
21762-697: The post-war period. A British mission led by Akers assisted in the development of gaseous diffusion technology at the SAM Laboratories in New York. Another, headed by Mark Oliphant , assisted with the electromagnetic separation process at the Berkeley Radiation Laboratory . Cockcroft became the director of the joint British-Canadian Montreal Laboratory . A British mission to the Los Alamos Laboratory
21948-403: The predicted yield had only been 1 megatonne of TNT (4.2 PJ). But it was still below the 2 megatonnes of TNT (8.4 PJ) safety limit. This was the real hydrogen bomb Britain wanted, but it used a relatively large quantity of expensive highly enriched uranium. Due to the higher-than-expected yield of the explosion, there was some damage to buildings, the fuel storage tanks, and helicopters on
22134-493: The prevailing wind pattern was interrupted. These were not common at this time of the year; at the start of Operation Mosaic, it had been estimated that conditions favourable for G2 would occur only three days per month. In fact, since Narvik had arrived in March, not a single day had been suitable. And good weather conditions alone were insufficient; the meteorologists had to accurately forecast them. To allow Narvik to return to
22320-474: The publication of details on the design, construction or location of atomic weapons. The project was given the cover name "High Explosive Research". Production facilities were constructed under the direction of Christopher Hinton , who established his headquarters in a former Royal Ordnance Factory at Risley in Lancashire . These included a uranium metal plant at Springfields , nuclear reactors and
22506-528: The purpose of the test itself. Aside from these technical considerations, tests have been conducted for political and training purposes, and can often serve multiple purposes. Computer simulation is used extensively to provide as much information as possible without physical testing. Mathematical models for such simulation model scenarios not only of performance but also of shelf life and maintenance . A theme has generally been that even though simulations cannot fully replace physical testing, they can reduce
22692-585: The recognised leader of the Commonwealth , and as a leading world power, had a position to maintain in world affairs. If our influence were to decline it would be virtually impossible to regain our rightful place as a world power. It was essential that the United Kingdom should have the ability to produce the H-Bomb in order that she could claim membership of the Allied H-Club. Thus, it was hoped that
22878-480: The scientific superintendent. Group Captain S. W. B. (Paddy) Menaul would command the Air Task Group. Planning was conducted at Aldermaston. On 18 July 1955 a five-man mission headed by Martell that included Adams, Menaul and Lieutenant Commanders A. K. Dodds and R. R. Fotheringham departed the UK for Australia. They arrived on 22 July, and began a series of discussions. The Australian Government created
23064-700: The senior Cabinet members, considered the political and strategic implications in June 1954, and concluded that "we must maintain and strengthen our position as a world power so that Her Majesty's Government can exercise a powerful influence in the counsels of the world." In July 1954, Cabinet agreed to proceed with the development of thermonuclear weapons. The scientists at the United Kingdom Atomic Energy Authority 's Atomic Weapons Establishment at Aldermaston in Berkshire included William Penney , William Cook , Ken Allen , Samuel Curran , Henry Hulme , Bryan Taylor and John Ward . They did not know how to build
23250-407: The series was Grapple 1, of Short Granite. This bomb was dropped from a height of 14,000 metres (45,000 ft) by a Vickers Valiant bomber of No. 49 Squadron RAF piloted by Wing Commander Kenneth Hubbard , off the shore of Malden Island at 11:38 local time on 15 May 1957. It was Britain's second airdrop of a nuclear bomb after the Operation Buffalo test at Maralinga on 11 October 1956, and
23436-427: The series were declassified in the 1990s, the tests were denounced as a hoax, but the reports were unlikely to have fooled the American observers. The next test was Grapple 2, of Orange Herald (small). This bomb was dropped at 10:44 local time on 31 May by another 49 Squadron Valiant, piloted by Squadron Leader Dave Roberts. It exploded with a force of 720 to 800 kilotonnes of TNT (3,000 to 3,300 TJ). The yield
23622-456: The study of Joe 19. It was found that there was a large amount of residual uranium-233 . The Soviet scientists had used this isotope so they could distinguish the behaviour of uranium in different parts of the system. This clarified that it was a two-stage device. Hulme prepared a paper in January 1956. At this point there were still three stages, Dick being a fission device and Harry the thermonuclear component. Two weeks later, Ken Allen produced
23808-491: The tamper. However, this is not the most important reaction. Corner and his theoretical physicists at Aldermaston argued that Green Granite could be made to work by increasing compression and reducing Taylor instability. The first step would be achieved with an improved Tom. The Red Beard Tom was given an improved high explosive supercharge, a composite (uranium-235 and plutonium) core, and a beryllium tamper, thereby increasing its yield to 45 kilotonnes of TNT (190 TJ). The Dick
23994-597: The target date. Oulton held the first meeting of the Grapple Executive Committee on New Oxford Street in London on 21 February 1956. The RAF and Royal Engineers would improve the airfield to enable it to operate large, heavily loaded aircraft, and the port and facilities would be improved to enable Christmas Island to operate as a base by 1 December 1956. It was estimated that 18,640 measurement tons (21,110 m ) of stores would be required for
24180-399: The team of scientists and technicians who have enabled us, single-handed, to keep virtually abreast of the United States in this complex and intricate business of nuclear weapons development. It is a tremendous achievement, of which they have every right to be very proud. The Anglo-American Special Relationship proved mutually beneficial, although it was never one of equals; the United States
24366-399: The test procedures were altered to allow for a break in the weather to be exploited, with an earlier firing time and a shorter countdown. Another complication was safety. While the test of a larger device would normally mandate a larger safety area, Beale announced that G2 was going to be smaller than G1. To avoid embarrassing him, the safety area was not enlarged, and no official announcement
24552-530: The tests as souvenirs. A pyramid-shaped obelisk marks the site of the G2 explosion on Alpha Island. Nuclear test The first nuclear device was detonated as a test by the United States at the Trinity site in New Mexico on July 16, 1945, with a yield approximately equivalent to 20 kilotons of TNT . The first thermonuclear weapon technology test of an engineered device, codenamed Ivy Mike ,
24738-511: The then four nuclear states and many non-nuclear states signed the Limited Test Ban Treaty , pledging to refrain from testing nuclear weapons in the atmosphere, underwater, or in outer space . The treaty permitted underground nuclear testing . France continued atmospheric testing until 1974, and China continued until 1980. Neither has signed the treaty. Underground tests conducted by the Soviet Union continued until 1990,
24924-595: The third country to test nuclear weapons. The first Blue Danube atomic bombs were delivered to Bomber Command in November 1953, although the V bombers to deliver them to their targets were not available until 1955. In the meantime, nuclear deterrence was provided by the United States Strategic Air Command , which had begun operating from British bases in 1949. The successful test of an atomic bomb represented an extraordinary scientific and technological achievement. Britain became
25110-537: The time, momentum was gathering both domestically and internationally for a moratorium on nuclear testing. The British Government was most anxious that this should not occur before Britain had developed hydrogen bombs, which it was hoped would be achieved in 1957. In thinking about thermonuclear designs, the British scientists at the Atomic Weapons Research Establishment at Aldermaston considered boosted fission weapons . These are
25296-580: The two countries pool their resources to meet the challenge. To do this, the McMahon Act's restrictions on nuclear cooperation needed to be relaxed. British information security , or the lack thereof, no longer seemed so important now that the Soviet Union was apparently ahead, and the United Kingdom had independently developed the hydrogen bomb. The trenchant opposition from the Joint Committee on Atomic Energy that had derailed previous attempts
25482-523: The uranium nucleus had been split. Hahn wrote to his colleague Lise Meitner , who, with her nephew Otto Robert Frisch , developed a theoretical explanation of the process. By analogy with the division of biological cells , they named the process " fission ". The discovery of fission raised the possibility that an extremely powerful atomic bomb could be created. Frisch and Rudolf Peierls , both German refugee scientists working in Britain, calculated
25668-544: The use of a natural uranium tamper . Although a boosted fission weapon is not a hydrogen bomb , which the British Government had agreed would not be tested in Australia, the tests were connected with the British hydrogen bomb programme . The Operation Totem tests of 1953 had been carried out at Emu Field in South Australia , but Emu Field was considered unsuitable for Operation Mosaic. A new, permanent test site
25854-465: The use of a natural uranium tamper . Two tests were therefore scheduled: one with a lead tamper to investigate the effect of lithium deuteride , and one with a natural uranium one to investigate effect of the tamper. It was hoped that the two tests would advance progress towards building a British hydrogen bomb. The need for speed dictated the location. The Operation Totem tests of 1953 had been carried out at Emu Field in South Australia , but it
26040-399: The use of nuclear weapons, and limited sharing of technical information. As Chief Superintendent Armament Research (CSAR, pronounced "Caesar"), Penney directed bomb design from Fort Halstead . In 1951 his design group moved to a new site at Aldermaston in Berkshire. The first British atomic bomb was successfully tested in Operation Hurricane on 3 October 1952. Britain thereby became
26226-630: The use of the Montebello Islands would save as much as six months' of development time. Menzies cabled his approval of the tests on 20 June. Like Operation Hurricane before it, the test was a Royal Navy responsibility. Planning commenced in February 1955 under the codename Operation Giraffe. In June 1955, the Admiralty adopted the codename Operation Mosaic. The Atomic Trials Executive in London, chaired by Lieutenant General Sir Frederick Morgan , had already begun planning Operation Buffalo. It assumed responsibility for Operation Mosaic as well, sitting as
26412-561: The use of the RAF and British Army. Nuclear material was also acquired from the United States. Under the Mutual Defence Agreement 5.4 tonnes of UK-produced plutonium was sent to the US in return for 6.7 kilograms (15 lb) of tritium and 7.5 tonnes of highly enriched uranium between 1960 and 1979, replacing Capenhurst production, although much of the highly enriched uranium was used not for weapons, but as fuel for
26598-455: The weapon materials would react. As a result, the explosion—with a yield of 15 Mt —was over twice what was predicted. Aside from this problem, the weapon also generated a large amount of radioactive nuclear fallout , more than had been anticipated, and a change in the weather pattern caused the fallout to spread in a direction not cleared in advance. The fallout plume spread high levels of radiation for over 100 miles (160 km), contaminating
26784-488: The world's third nuclear power , reaffirming the country's status as a great power, but hopes that the United States would be sufficiently impressed to restore the nuclear Special Relationship were soon dashed. In November 1952, the United States conducted the first successful test of a true thermonuclear device or hydrogen bomb. Britain was therefore still several years behind in nuclear weapons technology. The Defence Policy Committee, chaired by Churchill and consisting of
26970-490: The world's third nuclear power, reaffirming its status as a great power , but hopes that the United States would be sufficiently impressed to restore the Special Relationship were soon dashed. On 1 November 1952, the United States conducted Ivy Mike , the first successful test of a true thermonuclear device (also known as a hydrogen bomb). Due to its physical size and use of cryogenic liquid deuterium , it
27156-415: The yield was 25 kilotonnes of TNT (100 TJ), so this implied an upper limit was about 60 kilotonnes of TNT (250 TJ). Later an 80-kilotonne-of-TNT (330 TJ) limit was agreed to. Eden informed Menzies that the two shots would be from towers, which would produce a fifth of the fallout of that of Operation Hurricane, and there would be no danger to people or animals on the mainland. He explained that
27342-493: Was 1,352 explosions with a total yield of 90 Mt. The yields of atomic bombs and thermonuclear are typically measured in different amounts. Thermonuclear bombs can be hundreds or thousands of times stronger than their atomic counterparts. Due to this, thermonuclear bombs' yields are usually expressed in megatons which is about the equivalent of 1,000,000 tons of TNT. In contrast, atomic bombs' yields are typically measured in kilotons, or about 1,000 tons of TNT. In US context, it
27528-534: Was absent. Amendments to the Atomic Energy Act of 1954 passed Congress on 30 June 1958, and were signed into law by Eisenhower on 2 July 1958. The 1958 US–UK Mutual Defence Agreement was signed on 3 July, and was approved by Congress on 30 July. Macmillan called this "the Great Prize". The United States Atomic Energy Commission (AEC) invited the British government to send representatives to
27714-413: Was actually a large fission bomb was kept secret by the British government until the end of the Cold War . An Operational Requirement (OR1142) had been issued in 1955 for a thermonuclear warhead for a medium-range ballistic missile , which became Blue Streak . This was revised in November 1955, with "megaton" replacing "thermonuclear". Orange Herald (small) could then meet the requirement. A version
27900-602: Was also recruited at this time. British knowledge of thermonuclear weapons was based on work done at the Los Alamos Laboratory during the war. Two British scientists, Bretscher and Fuchs, had attended the conference there on the Super (as it was then called) in April 1946, and Chadwick had written a secret report on it in May 1946. The Classic Super design was unsuccessful. Fuchs and John von Neumann had produced an ingenious alternative design, for which they filed
28086-409: Was appointed task force commander, with the acting rank of air vice marshal from 1 March 1956. He had a formidable task ahead of him. Nearby Christmas Island was chosen as a base. It was claimed by both Britain and the United States, but the Americans were willing to let the British use it for the tests. With pressure mounting at home and abroad for a moratorium on testing, 1 April 1957 was set as
28272-558: Was assembled for Operation Mosaic. HMS Narvik began a refit at HM Dockyard, Chatham , in July 1955, which was completed by November. She departed the UK on 29 December 1955, and travelled via the Suez Canal , reaching Fremantle on 23 February 1956. The frigate HMS Alert , normally the yacht of the Commander-in-Chief, Far East Fleet , was loaned to act as an accommodation ship for scientists and VIPs. Along with
28458-464: Was being prepared at Maralinga in South Australia, but would not be ready until September 1956. It was decided that the best option was to return to the Montebello Islands, where Operation Hurricane had been conducted in 1952. To allow the task force flagship, the tank landing ship HMS Narvik , to return to the UK and refit in time for Operation Grapple , the planned first test of
28644-449: Was chosen in preference to a cylindrical one for ease of calculation; work on a cylindrical Dick was postponed until a new IBM 704 computer arrived from the United States. Implicit in the creation of a hydrogen bomb was that it would be tested. Eden, who replaced Churchill as prime minister after the latter's retirement, gave a radio broadcast in which he declared: "You cannot prove a bomb until it has exploded. Nobody can know whether it
28830-414: Was conducted near Alamogordo, New Mexico, on July 16, 1945, during the Manhattan Project , and given the codename " Trinity ". The test was originally to confirm that the implosion-type nuclear weapon design was feasible, and to give an idea of what the actual size and effects of a nuclear explosion would be before they were used in combat against Japan. While the test gave a good approximation of many of
29016-450: Was considered to be from radioactive seaweed, so they were prohibited from catching or eating fish, and the ships' evaporators were not run. Spot checks were made to verify that there was no contamination on board. Most of the sample collection was completed by 20 May. An extra run was made to collect film badges from Hermite Island, and Maddock paid the crater a visit on 25 May to collect further samples. Two RAF Canberra bombers flew through
29202-511: Was considered unsuitable. The area was too isolated, with the nearest road over 100 miles (160 km) away, and only tracked vehicles or those with special tyres could traverse the intervening sand dunes. Emu Field therefore relied on air transport, but dust storms were a problem. Moreover, a shortage of water severely limited the number of personnel at the site. A new, permanent test site was therefore being prepared at Maralinga in South Australia, but it would not be ready until September 1956, and
29388-417: Was couriered to the Montebello Islands by HMS Alert . Then followed a period of waiting for suitable weather conditions. The idea was to avoid, as far as possible, fallout being blown over the mainland. At this time of year winds at low altitudes were mainly subject to coastal influences, but above 10,000 feet (3,000 m) the prevailing winds were from the west. What was required was an interval during which
29574-402: Was created as an interim megaton weapon in order to provide the RAF with one at the earliest possible date. Codenamed Green Grass , the unsuccessful fusion boosting was omitted, and it used Green Bamboo's 72-lens implosion system instead of Orange Herald's 32. This allowed the amount of highly enriched uranium to be reduced from 120 kilograms (260 lb) to 75 kilograms (165 lb). Its yield
29760-564: Was critical of its organisation, which he blamed for slower progress than its Soviet counterpart. In particular, the programme had experienced problems with Civil Service pay and conditions, which were below those for comparable workers in industry. The Treasury had agreed to flexibility in exceptional cases, but the procedure was absurdly slow. Hinton in particular was concerned at the low remuneration his senior staff were receiving compared to those with similar responsibilities at ICI. When he attempted to bring Frank Kearton in as his successor,
29946-759: Was decided during the Manhattan Project that yield measured in tons of TNT equivalent could be imprecise. This comes from the range of experimental values of the energy content of TNT, ranging from 900 to 1,100 calories per gram (3,800 to 4,600 kJ/g). There is also the issue of which ton to use, as short tons, long tons, and metric tonnes all have different values. It was therefore decided that one kiloton would be equivalent to 1.0 × 10 calories (4.2 × 10 kJ). The nuclear powers have conducted more than 2,000 nuclear test explosions (numbers are approximate, as some test results have been disputed): There may also have been at least three alleged but unacknowledged nuclear explosions (see list of alleged nuclear tests ) including
30132-518: Was detected over northern Australia by monitoring stations, in combination with Beale's announcement that G2 would be smaller than G1, an impression was generated that something had gone horribly wrong. The acting prime minister, Sir Arthur Fadden , ordered an inquiry. Seamen in Fremantle demanded that the SS Koolinda , a cattle transport on which 75 cattle had died on board, be inspected, as it
30318-540: Was estimated at 0.5 megatonnes of TNT (2.1 PJ). It was placed in a Blue Danube casing, and this bomb became known as Violet Club . About ten were delivered before Yellow Sun became available. The third and final shot of the series was Grapple 3, the test of Purple Granite. This was dropped by a Valiant piloted by Squadron Leader Arthur Steele on 19 June. The yield was a very disappointing 300 kilotonnes of TNT (1,300 TJ), even less than Short Granite. The changes had not worked. "We haven't got it right", Cook told
30504-498: Was far larger than Britain both militarily and economically. Britain soon became dependent on the United States for its nuclear weapons, as it lacked the resources to produce a range of designs. The British decided to adapt the Mark 28 as a British weapon as a cheaper alternative to doing their own development, which became Red Snow . Other weapons were supplied through Project E , under which weapons in American custody were supplied for
30690-414: Was far more limited than that of G1. A Land Rover was landed from a Landing Craft Assault (LCA) and driven by a party wearing protective clothing to within 400 feet (120 m) of ground zero to collect samples and recover the blast measurement equipment. Another sortie was made to collect film badges from Hermite Island, and Maddock collected a sample from the G2 crater. The Canberra sent to fly through
30876-554: Was feared that they had died from radioactive poisoning. The seamen refused to unload the remaining 479 cattle. A physicist from the Commonwealth X-Ray and Radium Laboratory (CXRL) with a Geiger counter found no evidence of radioactive contamination , and the deaths were determined to have resulted from red water disease caused by a malaria-like parasite. It was estimated that someone living in Port Hedland , where
31062-443: Was given the cover name " High Explosive Research ". The first British atomic bomb was tested in Operation Hurricane at the Montebello Islands in Western Australia on 3 October 1952. Britain thereby became the third nuclear power after the United States and the Soviet Union, but just four weeks after Operation Hurricane, the United States successfully demonstrated a hydrogen bomb . The technology mastered in Operation Hurricane
31248-486: Was greatly simplified; instead of the 14 layers in Short Granite, it would have just three. This was called Round A; a five-layer version was also discussed, which was called Round B. A third round, Round C, was produced, for diagnostics. It had the same three layers as Round A, but an inert layer instead of lithium deuteride. Calculations for Round B were performed on the new IBM 704, while the old Ferranti Mark 1
31434-580: Was incontrovertible proof that, in some areas at least, the Soviet Union was actually ahead. In the widespread calls for action in response to the Sputnik crisis , officials in the United States and Britain seized an opportunity to mend the relationship with Britain that had been damaged by the Suez Crisis. At the suggestion of Harold Caccia , the British Ambassador to the United States , Macmillan wrote to Eisenhower on 10 October urging that
31620-663: Was led by Chadwick, and later Peierls, which included several of Britain's most eminent scientists. As overall head of the British Mission, Chadwick forged a close and successful partnership, and ensured that British participation was complete and wholehearted. With the end of the war the Special Relationship between Britain and the United States became, in the words of Margaret Gowing , "very much less special". The British government had trusted that America would share nuclear technology, which it considered
31806-406: Was made to the contrary. The weather improved on 8 June, and Martell ordered the countdown to begin the following day, but Beale objected to a test being carried out on a Sunday. During Operation Totem there was an agreement that no tests would be conducted on Sundays. Mosex considered that matter in London, and directed Martell not to test on 10 June. The following 48 hours were unsuitable. On 17 June
31992-547: Was not suitable for use as a deliverable weapon, but the Castle Bravo test on 1 March 1954 used a much smaller device with solid lithium deuteride . Boosted by the nuclear fusion reaction in lithium-7 , the yield of 15 megatonnes of TNT (63 PJ ) was more than twice what had been expected, and indeed was the largest detonation the Americans would ever carry out. This resulted in widespread radioactive fallout that affected 236 Marshall Islanders, 28 Americans, and
32178-488: Was not what their orders from London said. Penney sent a message to Adams 10 May: Strongly advise not showing Safety Committee any significant weapon details, but would not object to their seeing outside of cabled ball in centre section. They could be told that fissile material is at centre of large ball of high explosive and that elaborate electronics necessary to get symmetrical squash. No details of explosives configuration or inner components must be revealed. Appreciate that
32364-720: Was one of the main drivers for the ban of nuclear weapons testing, particularly atmospheric testing. It has been estimated that by 2020 up to 2.4 million people have died as a result of nuclear weapons testing. There are many existing anti-nuclear explosion treaties, notably the Partial Nuclear Test Ban Treaty and the Comprehensive Nuclear Test Ban Treaty . These treaties were proposed in response to growing international concerns about environmental damage among other risks. Nuclear testing involving humans also contributed to
32550-509: Was relatively infrequent (when the U.S. used two weapons for Operation Crossroads in 1946, they were detonating over 20% of their current arsenal). However, by the 1950s the United States had established a dedicated test site on its own territory ( Nevada Test Site ) and was also using a site in the Marshall Islands ( Pacific Proving Grounds ) for extensive atomic and nuclear testing. The early tests were used primarily to discern
32736-464: Was six years old, and with the hydrogen bomb in hand, the US Congress saw no benefit in renewing cooperation with the UK. All the while Britain strove for independence, at the same time it sought interdependence in the form of a renewal of the Special Relationship with the United States. The British Government therefore resolved on 27 July 1954 to initiate the British hydrogen bomb programme . At
32922-595: Was still several years behind in nuclear weapons technology, and while British and Soviet advances had taken much of the heat out of American opposition to renewed cooperation with the British, the United States Congress saw little benefit in it for the United States. The McMahon Act was amended by the Atomic Energy Act of 1954 on 30 August, which allowed for greater exchange of information with foreign nations, but it fell far short of what
33108-425: Was successful because much of its yield came from its thermonuclear reaction instead of fission of a heavy uranium-238 tamper, making it a true hydrogen bomb, and because its yield had been closely predicted—indicating that its designers understood what they were doing. On 22 August 1958, Eisenhower announced a moratorium on nuclear testing, effective 31 October 1958. This did not mean an immediate end to testing; on
33294-641: Was sufficiently impressed with the progress of works to schedule a scientific rehearsal for 27 April. A second scientific rehearsal was held on 2 May, followed by a full dress rehearsal on 5 May. The fissile material was delivered by an RAF Hastings to Onslow, from whence it was collected by HMS Alert on 11 May, and delivered to the Montebello Islands the following day. Five members of the AWTSC— Leslie H. Martin , Ernest Titterton , Cecil Eddy , Butement and Dwyer—arrived at Onslow and were flown to Narvik by helicopter on 14 May. The following day, Martell set 16 May as
33480-516: Was tested at the Enewetak Atoll in the Marshall Islands on November 1, 1952 (local date), also by the United States. The largest nuclear weapon ever tested was the Tsar Bomba of the Soviet Union at Novaya Zemlya on October 30, 1961, with the largest yield ever seen, an estimated 50–58 megatons . With the advent of nuclear technology and its increasing impact an anti-nuclear movement formed and in 1963, three (UK, US, Soviet Union) of
33666-405: Was the largest ever achieved by a single stage device, and made it technically a megaton weapon, but it was close to Corner's estimate for an unboosted yield, and Hulme doubted that the lithium-6 deuteride had contributed at all. This was chalked up to Taylor instability , which limited the compression of the light elements in the core. The bomb was hailed as a hydrogen bomb, and the truth that it
33852-535: Was there much more certainty about the boosted designs, with no agreement on whether the boosting thermonuclear fuel was best placed inside the hollow core, as in Orange Herald, or wrapped around it, as in Green Bamboo. Keith Roberts and John Ward studied the detonation waves in a thermonuclear detonation, but there was an incomplete understanding of radiation implosion. Additional information came from
34038-637: Was therefore required. For safety and security reasons, in light of the Lucky Dragon incident, a large site remote from population centres was required. Various remote islands in the South Pacific and Southern Oceans were considered, along with Antarctica. The Admiralty suggested the Antipodes Islands , which are about 860 kilometres (530 mi) southeast of New Zealand. In May 1955, the Minister for Defence, Selwyn Lloyd , concluded that
34224-517: Was to do away with the shells entirely and use a mixture of uranium-235, uranium-238 and deuterium. Ken Allen had an idea, which Sam Curran supported, of a three-layer Dick that used lithium deuteride that was less enriched in lithium-6 (and therefore had more lithium-7), but more of it, reducing the amount of uranium-235 in the centre of the core. This proposal was the one adopted in October, and it became known as "Dickens" because it used Ken's Dick. The device would otherwise be similar to Round A, but with
34410-621: Was too large to fit into a missile or guided bomb, this would occur whether or not Short Granite was a success. Finally, Green Granite would be tested. In December 1956, Cook had proposed another design, known as Green Granite II. This was smaller than Green Granite I, and could fit into a Yellow Sun casing that could be used by the Blue Steel guided missile then under development; but it could not be made ready to reach Christmas Island before 26 June 1957, and extending Operation Grapple would have cost another £1.5 million. The first test of
34596-399: Was used for the simpler Round A. The next trial was known as Grapple X. To save time and money, and as Narvik and the light aircraft carrier HMS Warrior were unavailable, the bomb would be dropped off the southern tip of Christmas Island rather than off Malden Island, just 20 nautical miles (37 km; 23 mi) from the airfield where 3,000 men would be based. This required
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