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215-748: The British hydrogen bomb programme was the ultimately successful British effort to develop hydrogen bombs between 1952 and 1958. During 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

430-410: A hohlraum or radiation case. The "George" shot of Operation Greenhouse of 9 May 1951 tested the basic concept for the first time on a very small scale. As the first successful (uncontrolled) release of nuclear fusion energy, which made up a small fraction of the 225  kt (940  TJ ) total yield, it raised expectations to a near certainty that the concept would work. On 1 November 1952,

645-547: 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 was not suitable for use as a deliverable weapon, but

860-736: A secondary section that consists of fusion fuel . The energy released by the primary compresses the secondary through the process of radiation implosion , at which point it is heated and undergoes nuclear fusion . This process could be continued, with energy from the secondary igniting a third fusion stage; the Soviet Union's AN602 " Tsar Bomba " is thought to have been a three-stage fission-fusion-fusion device. Theoretically by continuing this process thermonuclear weapons with arbitrarily high yield could be constructed. This contrasts with fission weapons, which are limited in yield because only so much fission fuel can be amassed in one place before

1075-430: A design could not produce thermonuclear weapons whose explosive yields could be made arbitrarily large (unlike U.S. designs at that time). The fusion layer wrapped around the fission core could only moderately multiply the fission energy (modern Teller–Ulam designs can multiply it 30-fold). Additionally, the whole fusion stage had to be imploded by conventional explosives, along with the fission core, substantially increasing

1290-427: 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

1505-491: 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

1720-498: A dozen megatons, which was generally considered enough to destroy even the most hardened practical targets (for example, a control facility such as the Cheyenne Mountain Complex ). Even such large bombs have been replaced by smaller yield nuclear bunker buster bombs. For destruction of cities and non-hardened targets, breaking the mass of a single missile payload down into smaller MIRV bombs in order to spread

1935-456: A few specific incidents outlined in a section below. The basic principle of the Teller–Ulam configuration is the idea that different parts of a thermonuclear weapon can be chained together in stages, with the detonation of each stage providing the energy to ignite the next stage. At a minimum, this implies a primary section that consists of an implosion-type fission bomb (a "trigger"), and

2150-462: 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

2365-480: 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

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2580-411: A fly at any distance with our missiles. Despite the wide radius of destruction caused by our nuclear warheads, pinpoint accuracy was still necessary – and it was difficult to achieve". At the time, Khrushchev stated that "our potential enemies cringe in fright". The political analyst Samuel Lubell conducted research on public opinion about Sputnik and found "no evidence at all of any panic or hysteria in

2795-474: 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 was successful because much of its yield came from its thermonuclear reaction instead of fission of

3010-517: 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 the contrary, the United States, the Soviet Union and the United Kingdom all rushed to perform as much testing as possible before

3225-453: A high-yield explosion. A W88 warhead manages to yield up to 475 kilotonnes of TNT (1,990 TJ) with a physics package 68.9 inches (1,750 mm) long, with a maximum diameter of 21.8 inches (550 mm), and by different estimates weighing in a range from 175 to 360 kilograms (386 to 794 lb). The smaller warhead allows more of them to fit onto a single missile and improves basic flight properties such as speed and range. The idea of

3440-504: 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

3655-651: 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

3870-413: 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

4085-428: A lower mass, or a combination of these benefits. Characteristics of nuclear fusion reactions make possible the use of non-fissile depleted uranium as the weapon's main fuel, thus allowing more efficient use of scarce fissile material such as uranium-235 ( U ) or plutonium-239 ( Pu ). The first full-scale thermonuclear test ( Ivy Mike ) was carried out by the United States in 1952, and

4300-693: A massive US crewed space program when he was in the US Senate during Eisenhower's term, public reaction to the Soviet's launch of the first human into orbit , Yuri Gagarin , on April 12, 1961, led Kennedy to raise the stakes of the Space Race by setting the goal of landing men on the Moon . Kennedy claimed, "If the Soviets control space they can control the earth, as in past centuries the nation that controlled

4515-488: A massive effort was mounted to re-invent the process. An impurity crucial to the properties of the old Fogbank was omitted during the new process. Only close analysis of new and old batches revealed the nature of that impurity. The manufacturing process used acetonitrile as a solvent , which led to at least three evacuations of the Fogbank plant in 2006. Widely used in the petroleum and pharmaceutical industries, acetonitrile

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4730-471: 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

4945-601: 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

5160-532: A month of the satellite launch helped to dispel some of the fears created by the Sputnik launch. However, Sputnik was not part of an organized effort to dominate space according to a Soviet space scientist. The successful launch of Sputnik 1 and then the subsequent failure of the first two Project Vanguard launch attempts greatly accentuated the US perception of a threat from the Soviet Union that had persisted since

5375-411: A moral panic by writing sensational pieces on the event. In the first and second days following the event, The New York Times wrote that the launch of Sputnik 1 was a major global propaganda and prestige triumph for Russian communism. Further, Fred Hechinger, a noted American journalist and education editor, reported, “hardly a week passed without several television programs examining education". It

5590-404: 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

5805-474: 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

6020-605: 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

6235-490: 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

6450-576: A possibility. It was first used in thermonuclear weapons with the W76 thermonuclear warhead and produced at a plant in the Y-12 Complex at Oak Ridge, Tennessee , for use in the W76. Production of Fogbank lapsed after the W76 production run ended. The W76 Life Extension Program required more Fogbank to be made. This was complicated by the fact that the original Fogbank's properties were not fully documented, so

6665-687: 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

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6880-524: 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

7095-442: 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

7310-584: A strong economy. In Britain, the launch of the first Sputnik provoked surprise, combined with elation at experiencing the dawn of the Space Age . It was also a reminder of the decline in the British Empire's world influence . The crisis soon became part of the broader Cold War narrative. The Daily Express predicted that "The result will be a new [U.S.] drive to catch up and pass the Russians in

7525-406: A substantial leap in technology, which was interpreted as a serious threat to US national security, spurring the US to boost federal investment in research and development, education, and national security. The Juno I rocket that carried the first US satellite Explorer 1 was ready to launch in 1956, but that fact was classified and unknown to the public. The Army's PGM-19 Jupiter from which Juno

7740-485: A thermal barrier to keep the fusion fuel filler from becoming too hot, which would spoil the compression. If made of uranium , enriched uranium or plutonium, the tamper captures fast fusion neutrons and undergoes fission itself, increasing the overall explosive yield . Additionally, in most designs the radiation case is also constructed of a material that undergoes fission driven by fast thermonuclear neutrons. Such bombs are classified as two stage weapons. Fast fission of

7955-602: A thermonuclear fusion bomb ignited by a smaller fission bomb was first proposed by Enrico Fermi to his colleague Edward Teller when they were talking at Columbia University in September 1941, at the start of what would become the Manhattan Project . Teller spent much of the Manhattan Project attempting to figure out how to make the design work, preferring it over work on the atomic bomb, and over

8170-441: A thermonuclear warhead can flash down from space at hypersonic speed to reach any spot on Earth minutes after its launching". Former US Rear Admiral Rawson Bennett, chief of naval operations, stated that Sputnik was a "hunk of iron almost anybody could launch", while former US Army general James M. Gavin described it as "the most significant military event of our time". The Sputnik crisis also spurred substantial transformation in

8385-459: 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 a larger radiation case. The safety limit

8600-496: 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

8815-530: 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

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9030-630: 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

9245-536: 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

9460-461: Is flammable and toxic. Y-12 is the sole producer of Fogbank. A simplified summary of the above explanation is: How exactly the energy is "transported" from the primary to the secondary has been the subject of some disagreement in the open press but is thought to be transmitted through the X-rays and gamma rays that are emitted from the fissioning primary . This energy is then used to compress

9675-487: Is omitted, by replacing the uranium tamper with one made of lead , for example, the overall explosive force is reduced by approximately half but the amount of fallout is relatively low. The neutron bomb is a hydrogen bomb with an intentionally thin tamper, allowing as many of the fast fusion neutrons as possible to escape. Current technical criticisms of the idea of "foam plasma pressure" focus on unclassified analysis from similar high energy physics fields that indicate that

9890-529: Is one order of magnitude greater than the higher proposed plasma pressures and nearly two orders of magnitude greater than calculated radiation pressure. No mechanism to avoid the absorption of energy into the radiation case wall and the secondary tamper has been suggested, making ablation apparently unavoidable. The other mechanisms appear to be unneeded. United States Department of Defense official declassification reports indicate that foamed plastic materials are or may be used in radiation case liners, and despite

10105-462: Is the Soviet early Sloika design. In essence, the Teller–Ulam configuration relies on at least two instances of implosion occurring: first, the conventional (chemical) explosives in the primary would compress the fissile core, resulting in a fission explosion many times more powerful than that which chemical explosives could achieve alone (first stage). Second, the radiation from the fissioning of

10320-426: Is the fusion fuel, usually a form of lithium deuteride , which is used because it is easier to weaponize than liquefied tritium/deuterium gas. This dry fuel, when bombarded by neutrons, produces tritium, a heavy isotope of hydrogen that can undergo nuclear fusion, along with the deuterium present in the mixture. (See the article on nuclear fusion for a more detailed technical discussion of fusion reactions.) Inside

10535-446: Is the medium by which the outside pressure (force acting on the surface area of the secondary) is transferred to the mass of fusion fuel. The proposed tamper-pusher ablation mechanism posits that the outer layers of the thermonuclear secondary's tamper-pusher are heated so extremely by the primary's X-ray flux that they expand violently and ablate away (fly off). Because total momentum is conserved, this mass of high velocity ejecta impels

10750-416: Is the primary example). Such processes have resulted in a body of unclassified knowledge about nuclear bombs that is generally consistent with official unclassified information releases and related physics and is thought to be internally consistent, though there are some points of interpretation that are still considered open. The state of public knowledge about the Teller–Ulam design has been mostly shaped from

10965-552: Is thought to be a standard implosion method fission bomb, though likely with a core boosted by small amounts of fusion fuel (usually 1:1 deuterium : tritium gas) for extra efficiency; the fusion fuel releases excess neutrons when heated and compressed, inducing additional fission. When fired, the Pu or U core would be compressed to a smaller sphere by special layers of conventional high explosives arranged around it in an explosive lens pattern, initiating

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11180-495: Is thought to have used multiple stages (including more than one tertiary fusion stage) in their 50 Mt (210 PJ) (100 Mt (420 PJ) in intended use) Tsar Bomba. The fissionable jacket could be replaced with lead, as was done with the Tsar Bomba. If any hydrogen bombs have been made from configurations other than those based on the Teller–Ulam design, the fact of it is not publicly known. A possible exception to this

11395-409: Is widely assumed to be beryllium , which fits that description and would also moderate the neutron flux from the primary. Some material to absorb and re-radiate the X-rays in a particular manner may also be used. Candidates for the "special material" are polystyrene and a substance called " Fogbank ", an unclassified codename. Fogbank's composition is classified, though aerogel has been suggested as

11610-493: 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

11825-655: 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

12040-597: The Cold War had begun after World War II . The same rocket that launched Sputnik could send a nuclear warhead anywhere in the world in a matter of minutes, which would strip the Continental United States of its oceanic defenses. The Soviets had demonstrated that capability on 21 August by a 6,000-kilometer (3,700-mile) test flight of the R-7 booster . The event was announced by TASS five days later and

12255-527: The Cold War that triggered the creation of NASA and the Space Race between the two superpowers. The satellite was launched on October 4, 1957, from the Baikonur Cosmodrome . This created a crisis reaction in national newspapers such as The New York Times , which mentioned the satellite in 279 articles between October 6, 1957, and October 31, 1957 (more than 11 articles per day). In

12470-505: 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

12685-694: 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,

12900-583: The National Aeronautics and Space Act , the creation of NASA . Less than a year after the Sputnik launch, Congress passed the National Defense Education Act (NDEA). It was a four-year program that poured billions of dollars into the US education system. In 1953, the government spent $ 153 million, and colleges took $ 10 million of that funding, but by 1960, the combined funding grew almost six-fold because of

13115-618: 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

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13330-570: The Trident II SLBM, had a prolate primary (code-named Komodo ) and a spherical secondary (code-named Cursa ) inside a specially shaped radiation case (known as the "peanut" for its shape). The value of an egg-shaped primary lies apparently in the fact that a MIRV warhead is limited by the diameter of the primary: if an egg-shaped primary can be made to work properly, then the MIRV warhead can be made considerably smaller yet still deliver

13545-458: The UK Polaris programme and Trident nuclear programme using American missiles with British nuclear warheads. Hydrogen bombs A thermonuclear weapon , fusion weapon or hydrogen bomb ( H bomb ) is a second-generation nuclear weapon design . Its greater sophistication affords it vastly greater destructive power than first-generation nuclear bombs , a more compact size,

13760-598: 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

13975-505: 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 the world's third nuclear power, reaffirming its status as

14190-688: 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

14405-612: The W-80 the gas expansion velocity is roughly 410 km/s (41 cm/μs) and the implosion velocity 570 km/s (57 cm/μs). The pressure due to the ablating material is calculated to be 5.3  billion bars (530  trillion pascals ) in the Ivy Mike device and 64 billion bars (6.4 quadrillion pascals) in the W-80 device. Comparing the three mechanisms proposed, it can be seen that: The calculated ablation pressure

14620-547: The W47 warhead deployed on Polaris ballistic missile submarines , megaton-class warheads were as small as 18 inches (0.46 m) in diameter and 720 pounds (330 kg) in weight. Further innovation in miniaturizing warheads was accomplished by the mid-1970s, when versions of the Teller–Ulam design were created that could fit ten or more warheads on the end of a small MIRVed missile. The first Soviet fusion design, developed by Andrei Sakharov and Vitaly Ginzburg in 1949 (before

14835-418: 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

15050-558: The neutron flux from the primary to prematurely begin heating the secondary, weakening the compression enough to prevent any fusion. There is very little detailed information in the open literature about the mechanism of the interstage. One of the best sources is a simplified diagram of a British thermonuclear weapon similar to the American W80 warhead. It was released by Greenpeace in a report titled "Dual Use Nuclear Technology" . The major components and their arrangement are in

15265-408: The nuclear chain reaction that powers the conventional "atomic bomb". The secondary is usually shown as a column of fusion fuel and other components wrapped in many layers. Around the column is first a "pusher- tamper ", a heavy layer of uranium-238 ( U ) or lead that helps compress the fusion fuel (and, in the case of uranium, may eventually undergo fission itself). Inside this

15480-460: The secondary . The crucial detail of how the X-rays create the pressure is the main remaining disputed point in the unclassified press. There are three proposed theories: The radiation pressure exerted by the large quantity of X-ray photons inside the closed casing might be enough to compress the secondary. Electromagnetic radiation such as X-rays or light carries momentum and exerts a force on any surface it strikes. The pressure of radiation at

15695-630: 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

15910-604: 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

16125-644: 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 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,

16340-534: 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

16555-469: The British fusion bomb, with Sir William Penney in charge of the project. British knowledge on how to make a thermonuclear fusion bomb was rudimentary, and at the time the United States was not exchanging any nuclear knowledge because of the Atomic Energy Act of 1946 . The United Kingdom had worked closely with the Americans on the Manhattan Project. British access to nuclear weapons information

16770-523: 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 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

16985-432: 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 ,

17200-488: 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

17415-486: 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

17630-480: The Earth, the US became a second-rate power. Politicians used the event to bolster their ratings in polls. Research and development was used as a propaganda tool, and Congress spent large sums of money on the perceived problem of US technological deficiency. After the launch of Sputnik 1 national security advisers overestimated the Soviets' current and potential rocket strength, which alarmed portions of Congress and

17845-546: 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

18060-491: 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

18275-581: 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

18490-476: The NDEA. After the initial public shock, the Space Race began, which led to the first human launched into space , Project Apollo , and the first humans to land on the Moon in 1969. Campaigning in 1960 on closing the " missile gap ", Eisenhower's successor, John F. Kennedy , promised to deploy 1,000 Minuteman missiles . That was many more ICBMs than the Soviets had at the time. Though Kennedy did not favor

18705-483: 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

18920-694: 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 ,

19135-589: 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

19350-526: The Soviet Union, United Kingdom, France, China and India. The thermonuclear Tsar Bomba was the most powerful bomb ever detonated. As thermonuclear weapons represent the most efficient design for weapon energy yield in weapons with yields above 50 kilotons of TNT (210 TJ), virtually all the nuclear weapons of this size deployed by the five nuclear-weapon states under the Non-Proliferation Treaty today are thermonuclear weapons using

19565-458: The Soviet rocket that launched Sputnik into space must have produced 200,000 pounds-force (890,000 N) of thrust. In fact, the R-7 rocket that launched Sputnik 1 into space produced almost 1,000,000 pounds-force (4,400,000 N) of thrust. All of those factors contributed to the Americans' perception that they were greatly behind the Soviets in the development of space technologies. Hours after

19780-475: The Soviets had a working fission bomb), was dubbed the Sloika , after a Russian layer cake , and was not of the Teller–Ulam configuration. It used alternating layers of fissile material and lithium deuteride fusion fuel spiked with tritium (this was later dubbed Sakharov's "First Idea"). Though nuclear fusion might have been technically achievable, it did not have the scaling property of a "staged" weapon. Thus, such

19995-431: The Soviets had rockets capable of sending nuclear weapons to Western Europe and even North America. That was the most immediate threat that Sputnik 1 posed. The United States, a land with a history of geographical security from European wars because of its distance, suddenly seemed vulnerable. A contributing factor to the Sputnik crisis was that the Soviets had not released a photograph of the satellite for five days after

20210-442: The Soviets searched for an alternative design. The "Second Idea", as Sakharov referred to it in his memoirs, was a previous proposal by Ginzburg in November 1948 to use lithium deuteride in the bomb, which would, in the course of being bombarded by neutrons, produce tritium and free deuterium. In late 1953 physicist Viktor Davidenko achieved the first breakthrough of staging the reactions. The next breakthrough of radiation implosion

20425-447: The Sputnik crisis, leaders exploited an "awe doctrine" to organize learning "around a strong model of educational national security: with math and science serving for supremacy in science and engineering, foreign languages and cultures for potential espionage, and history and humanities for national self-definition". US leaders were not able to exploit the image of Japan as effectively, despite its representations of super-smart students and

20640-673: The Teller–Ulam configuration was tested at full scale in the "Ivy Mike" shot at an island in the Enewetak Atoll , with a yield of 10.4  Mt (44  PJ ) (over 450 times more powerful than the bomb dropped on Nagasaki during World War II ). The device, dubbed the Sausage , used an extra-large fission bomb as a "trigger" and liquid deuterium—kept in its liquid state by 20 short tons (18  t ) of cryogenic equipment—as its fusion fuel, and weighed around 80 short tons (73  t ) altogether. The liquid deuterium fuel of Ivy Mike

20855-429: The Teller–Ulam design. Detailed knowledge of fission and fusion weapons is classified to some degree in virtually every industrialized country . In the United States, such knowledge can by default be classified as " Restricted Data ", even if it is created by persons who are not government employees or associated with weapons programs, in a legal doctrine known as " born secret " (though the constitutional standing of

21070-563: 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

21285-435: The U.S. and Soviets, achieving only approximately 300 kt (1,300 TJ). The second test Orange Herald was the modified fission bomb and produced 720 kt (3,000 TJ)—making it the largest fission explosion ever. At the time almost everyone (including the pilots of the plane that dropped it) thought that this was a fusion bomb. This bomb was put into service in 1958. A second prototype fusion bomb, Purple Granite ,

21500-493: The U.S. government has attempted to censor weapons information in the public press , with limited success. According to the New York Times , physicist Kenneth W. Ford defied government orders to remove classified information from his book Building the H Bomb: A Personal History . Ford claims he used only pre-existing information and even submitted a manuscript to the government, which wanted to remove entire sections of

21715-490: The US science policy, which provided much of the basis for modern academic scientific research. Astronomer John Jefferies, at the High Altitude Observatory in 1957, recalled that it had received funding mostly from philanthropists. "The week after Sputnik went up, we were digging ourselves out of this avalanche of money that suddenly descended" from the federal government, he said. By the mid-1960s, NASA

21930-455: 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 the use of the RAF and British Army. Nuclear material

22145-407: The United States needed to meet these challenges with "resourcefulness and vigor". The president also noted the importance of education for the Russians in their recent scientific and technological progress, and for America's response to the Russians. He remarked, "we need scientists in the ten years ahead...scrutinize your school's curriculum and standards. Then decide for yourselves whether they meet

22360-494: The X-ray energy impinging on its pusher/ tamper. This compresses the entire secondary stage and drives up the density of the plutonium spark plug. The density of the plutonium fuel rises to such an extent that the spark plug is driven into a supercritical state, and it begins a nuclear fission chain reaction . The fission products of this chain reaction heat the highly compressed (and thus super dense) thermonuclear fuel surrounding

22575-411: The amount of chemical explosives needed. The first Sloika design test, RDS-6s , was detonated in 1953 with a yield equivalent to 400 kt (1,700 TJ) ( 15%- 20% from fusion). Attempts to use a Sloika design to achieve megaton-range results proved unfeasible. After the United States tested the "Ivy Mike" thermonuclear device in November 1952, proving that a multimegaton bomb could be created,

22790-422: The argument that Sputnik was only a scientific achievement and not a military threat or change in world power. He believed that Sputnik's weight "was not commensurate with anything of great military significance, and that was also a factor in putting it in [proper] perspective". In 1958, Eisenhower declared three "stark facts" the United States needed to confront: Eisenhower followed this statement by saying that

23005-686: 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

23220-479: 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

23435-446: The book for concern that foreign states could use the information. Though large quantities of vague data have been officially released—and larger quantities of vague data have been unofficially leaked by former bomb designers—most public descriptions of nuclear weapon design details rely to some degree on speculation, reverse engineering from known information, or comparison with similar fields of physics ( inertial confinement fusion

23650-481: The casing to a plasma, which then re-radiated radiation into the secondary's pusher, causing its surface to ablate and driving it inwards, compressing the secondary, igniting the sparkplug, and causing the fusion reaction. The general applicability of this principle is unclear. In 1999 a reporter for the San Jose Mercury News reported that the U.S. W88 nuclear warhead, a small MIRVed warhead used on

23865-440: The casing's circumference. The neutron guns are tilted so the neutron emitting end of each gun end is pointed towards the central axis of the bomb. Neutrons from each neutron gun pass through and are focused by the neutron focus lens towards the centre of primary in order to boost the initial fissioning of the plutonium. A " polystyrene Polarizer/Plasma Source" is also shown (see below). The first U.S. government document to mention

24080-629: 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

24295-401: The concept has since been employed by most of the world's nuclear powers in the design of their weapons. Modern fusion weapons essentially consist of two main components: a nuclear fission primary stage (fueled by U or Pu ) and a separate nuclear fusion secondary stage containing thermonuclear fuel: heavy isotopes of hydrogen ( deuterium and tritium ) as

24510-412: The conditions needed for fusion, and the idea of staging or placing a separate thermonuclear component outside a fission primary component, and somehow using the primary to compress the secondary. Teller then realized that the gamma and X-ray radiation produced in the primary could transfer enough energy into the secondary to create a successful implosion and fusion burn, if the whole assembly was wrapped in

24725-558: 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

24940-523: The danger of its accidentally becoming supercritical becomes too great. Surrounding the other components is a hohlraum or radiation case , a container that traps the first stage or primary's energy inside temporarily. The outside of this radiation case, which is also normally the outside casing of the bomb, is the only direct visual evidence publicly available of any thermonuclear bomb component's configuration. Numerous photographs of various thermonuclear bomb exteriors have been declassified. The primary

25155-491: 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 the Pendant and Burgee tests, allowing

25370-547: 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

25585-416: The decision to go forward with the development of the new weapon. Teller and other U.S. physicists struggled to find a workable design. Stanislaw Ulam , a co-worker of Teller, made the first key conceptual leaps towards a workable fusion design. Ulam's two innovations that rendered the fusion bomb practical were that compression of the thermonuclear fuel before extreme heating was a practical path towards

25800-518: 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

26015-586: 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

26230-424: The diagram, though details are almost absent; what scattered details it does include likely have intentional omissions or inaccuracies. They are labeled "End-cap and Neutron Focus Lens" and "Reflector Wrap"; the former channels neutrons to the U / Pu Spark Plug while the latter refers to an X-ray reflector; typically a cylinder made of an X-ray opaque material such as uranium with

26445-479: The doctrine has been at times called into question; see United States v. Progressive, Inc. ). Born secret is rarely invoked for cases of private speculation. The official policy of the United States Department of Energy has been not to acknowledge the leaking of design information, as such acknowledgment would potentially validate the information as accurate. In a small number of prior cases,

26660-417: The early 1950s, Lockheed U-2 spy plane flights over the Soviet Union provided intelligence that the US held the advantage in nuclear capability. However, an education gap was identified when studies conducted between 1955 and 1961 reported that the Soviet Union was training two to three times as many scientists per year as the US. The launch and orbit of Sputnik 1 suggested that the Soviet Union had made

26875-414: The effects of that absorbed energy led to the third mechanism: ablation . The outer casing of the secondary assembly is called the "tamper-pusher". The purpose of a tamper in an implosion bomb is to delay the expansion of the reacting fuel supply (which is very hot dense plasma) until the fuel is fully consumed and the explosion runs to completion. The same tamper material serves also as a pusher in that it

27090-512: The energy of the explosions into a "pancake" area is far more efficient in terms of area-destruction per unit of bomb energy. This also applies to single bombs deliverable by cruise missile or other system, such as a bomber, resulting in most operational warheads in the U.S. program having yields of less than 500 kt (2,100 TJ). In his 1995 book Dark Sun: The Making of the Hydrogen Bomb , author Richard Rhodes describes in detail

27305-409: The executive branch. When these estimations were released, Eisenhower was forced into an accelerated missile race to appease those concerned with America's safety. Sputnik provoked Congress into taking action on improving the US standing in the fields of science. Nikita Khrushchev , the Soviet leader, reflected on the event by saying, "It always sounded good to say in public speeches that we could hit

27520-487: 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, the IBM 704 had to be turned over to them, and there

27735-519: The far more powerful Super. The debate covered matters that were alternatively strategic, pragmatic, and moral. In their Report of the General Advisory Committee, Robert Oppenheimer and colleagues concluded that "[t]he extreme danger to mankind inherent in the proposal [to develop thermonuclear weapons] wholly outweighs any military advantage." Despite the objections raised, on 31 January 1950, President Harry S. Truman made

27950-415: 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

28165-490: 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

28380-436: The fissioning of the final natural uranium tamper, something that could not normally be achieved without the neutron flux provided by the fusion reactions in secondary or tertiary stages. Such designs are suggested to be capable of being scaled up to an arbitrary large yield (with apparently as many fusion stages as desired), potentially to the level of a " doomsday device ." However, usually such weapons were not more than

28595-504: The gap between the Neutron Focus Lens (in the center) and the outer casing near the primary. It separates the primary from the secondary and performs the same function as the previous reflector. There are about six neutron guns (seen here from Sandia National Laboratories ) each protruding through the outer edge of the reflector with one end in each section; all are clamped to the carriage and arranged more or less evenly around

28810-602: 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

29025-415: 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

29240-462: The intensities seen in everyday life, such as sunlight striking a surface, is usually imperceptible, but at the extreme intensities found in a thermonuclear bomb the pressure is enormous. For two thermonuclear bombs for which the general size and primary characteristics are well understood, the Ivy Mike test bomb and the modern W-80 cruise missile warhead variant of the W-61 design, the radiation pressure

29455-420: The internal components of the "Ivy Mike" Sausage device, based on information obtained from extensive interviews with the scientists and engineers who assembled it. According to Rhodes, the actual mechanism for the compression of the secondary was a combination of the radiation pressure, foam plasma pressure, and tamper-pusher ablation theories; the radiation from the primary heated the polyethylene foam lining of

29670-504: The interstage was only recently released to the public promoting the 2004 initiation of the Reliable Replacement Warhead (RRW) Program. A graphic includes blurbs describing the potential advantage of a RRW on a part-by-part level, with the interstage blurb saying a new design would replace "toxic, brittle material" and "expensive 'special' material... [that require] unique facilities". The "toxic, brittle material"

29885-503: 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

30100-528: The last year of the project he was assigned exclusively to the task. However once World War II ended, there was little impetus to devote many resources to the Super , as it was then known. The first atomic bomb test by the Soviet Union in August 1949 came earlier than expected by Americans, and over the next several months there was an intense debate within the U.S. government, military, and scientific communities regarding whether to proceed with development of

30315-479: The launch, the University of Illinois at Urbana–Champaign Astronomy Department rigged an ad hoc interferometer to measure signals from the satellite. Donald B. Gillies and Jim Snyder programmed the ILLIAC I computer to calculate the satellite orbit from this data. The programming and calculation was completed in less than two days. The rapid publication of the ephemeris (orbit) in the journal Nature within

30530-400: The launch. Until then, its appearance remained a mystery to Americans. Another factor was its weight of 184 pounds (83 kg), compared to US plans to launch a satellite of 21.5 pounds (9.8 kg). The Soviet claim seemed outrageous to many American officials, who doubted its accuracy. US rockets then produced 150,000 pounds-force (670,000 N) of thrust , and US officials presumed that

30745-415: The layer of fuel is the " spark plug ", a hollow column of fissile material ( Pu or U ) often boosted by deuterium gas. The spark plug, when compressed, can undergo nuclear fission (because of the shape, it is not a critical mass without compression). The tertiary, if one is present, would be set below the secondary and probably be made of the same materials. Separating

30960-426: The lead in space exploration from the Soviets, and it fueled its drive to land men on the Moon . American officials had a variety of opinions at the time, some registering alarm and others dismissing the satellite. Gerald Ford , a Republican US representative from Michigan, had stated, "We Middle Westerners are sometimes called isolationists. I don't agree with the label; but there can be no isolationists anywhere when

31175-432: The low direct plasma pressure they may be of use in delaying the ablation until energy has distributed evenly and a sufficient fraction has reached the secondary's tamper/pusher. Richard Rhodes ' book Dark Sun stated that a 1-inch-thick (25 mm) layer of plastic foam was fixed to the lead liner of the inside of the Ivy Mike steel casing using copper nails. Rhodes quotes several designers of that bomb explaining that

31390-490: 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 the Quebec Conference in August 1943,

31605-600: 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

31820-470: 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

32035-490: 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 the senior Cabinet members, considered the political and strategic implications in June 1954, and concluded that "we must maintain and strengthen our position as

32250-424: The outer radiation case, with the components coming to a thermal equilibrium , and the effects of that thermal energy are then analyzed. The energy is mostly deposited within about one X-ray optical thickness of the tamper/pusher outer surface, and the temperature of that layer can then be calculated. The velocity at which the surface then expands outwards is calculated and, from a basic Newtonian momentum balance,

32465-438: The plastic foam layer inside the outer case is to delay ablation and thus recoil of the outer case: if the foam were not there, metal would ablate from the inside of the outer case with a large impulse, causing the casing to recoil outwards rapidly. The purpose of the casing is to contain the explosion for as long as possible, allowing as much X-ray ablation of the metallic surface of the secondary stage as possible, so it compresses

32680-693: 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

32895-413: The pressure produced by such a plasma would only be a small multiplier of the basic photon pressure within the radiation case, and also that the known foam materials intrinsically have a very low absorption efficiency of the gamma ray and X-ray radiation from the primary. Most of the energy produced would be absorbed by either the walls of the radiation case or the tamper around the secondary. Analyzing

33110-519: The primary and secondary assemblies placed within an enclosure called a radiation case, which confines the X-ray energy and resists its outward pressure. The distance separating the two assemblies ensures that debris fragments from the fission primary (which move much more slowly than X-ray photons ) cannot disassemble the secondary before the fusion explosion runs to completion. The secondary fusion stage—consisting of outer pusher/ tamper , fusion fuel filler and central plutonium spark plug—is imploded by

33325-442: The primary and secondary at either end. It does not reflect like a mirror; instead, it gets heated to a high temperature by the X-ray flux from the primary, then it emits more evenly spread X-rays that travel to the secondary, causing what is known as radiation implosion . In Ivy Mike , gold was used as a coating over the uranium to enhance the blackbody effect. Next comes the "Reflector/Neutron Gun Carriage". The reflector seals

33540-425: The primary would be used to compress and ignite the secondary fusion stage, resulting in a fusion explosion many times more powerful than the fission explosion alone. This chain of compression could conceivably be continued with an arbitrary number of tertiary fusion stages, each igniting more fusion fuel in the next stage although this is debated. Finally, efficient bombs (but not so-called neutron bombs ) end with

33755-455: The public's reaction", which confirmed that it was an elite, not a popular, panic. The week after Sputnik went up, we were digging ourselves out of this avalanche of money that suddenly descended. The launch spurred a series of US initiatives ranging from defense to education. Increased emphasis was placed on the US Navy 's Project Vanguard to launch an American satellite into orbit. There

33970-469: 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

34185-448: The pure element or in modern weapons lithium deuteride . For this reason, thermonuclear weapons are often colloquially called hydrogen bombs or H-bombs . A fusion explosion begins with the detonation of the fission primary stage. Its temperature soars past 100 million kelvin , causing it to glow intensely with thermal ("soft") X-rays . These X-rays flood the void (the "radiation channel" often filled with polystyrene foam ) between

34400-584: 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

34615-418: The rest of the tamper-pusher to recoil inwards with tremendous force, crushing the fusion fuel and the spark plug. The tamper-pusher is built robustly enough to insulate the fusion fuel from the extreme heat outside; otherwise, the compression would be spoiled. Rough calculations for the basic ablation effect are relatively simple: the energy from the primary is distributed evenly onto all of the surfaces within

34830-412: The seas dominated the continents." Eisenhower disagreed with Kennedy's goal and referred to it as a "stunt". Kennedy had privately acknowledged that the space race was a waste of money, but he knew there were benefits from a frightened electorate. The Space Race was less about its intrinsic importance and more about prestige and calming the public. The Sputnik crisis sparked the American drive to retake

35045-450: The secondary efficiently, maximizing the fusion yield. Plastic foam has a low density, so causes a smaller impulse when it ablates than metal does. Possible variations to the weapon design have been proposed: Most bombs do not apparently have tertiary "stages"—that is, third compression stage(s), which are additional fusion stages compressed by a previous fusion stage. The fissioning of the last blanket of uranium, which provides about half

35260-422: The secondary from the primary is the interstage . The fissioning primary produces four types of energy: 1) expanding hot gases from high explosive charges that implode the primary; 2) superheated plasma that was originally the bomb's fissile material and its tamper; 3) the electromagnetic radiation ; and 4) the neutrons from the primary's nuclear detonation. The interstage is responsible for accurately modulating

35475-594: The secondary stages by radiation implosion. Because of these difficulties, in 1955 Prime Minister Anthony Eden agreed to a secret plan, whereby if the Aldermaston scientists failed or were greatly delayed in developing the fusion bomb, it would be replaced by an extremely large fission bomb. In 1957 the Operation Grapple tests were carried out. The first test, Green Granite, was a prototype fusion bomb that failed to produce equivalent yields compared to

35690-473: 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

35905-424: 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

36120-418: The spark plug to around 300 million kelvin, igniting fusion reactions between fusion fuel nuclei. In modern weapons fueled by lithium deuteride, the fissioning plutonium spark plug also emits free neutrons that collide with lithium nuclei and supply the tritium component of the thermonuclear fuel. The secondary's relatively massive tamper (which resists outward expansion as the explosion proceeds) also serves as

36335-403: The stern demands of the era we are entering." His ability to project confidence about the situation was limited because his confidence was based on clandestine reconnaissance, so he failed to quell the fears that there was a shift in power between the Americans and Soviets. The launch of Sputnik 1 also impacted Eisenhower's ratings in his polls, but he eventually recovered. The media stirred

36550-456: 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

36765-407: The tamper and radiation case is the main contribution to the total yield and is the dominant process that produces radioactive fission product fallout . Before Ivy Mike, Operation Greenhouse in 1951 was the first American nuclear test series to test principles that led to the development of thermonuclear weapons. Sufficient fission was achieved to boost the associated fusion device, and enough

36980-491: 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

37195-594: 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

37410-493: 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 was far larger than Britain both militarily and economically. Britain soon became dependent on

37625-404: The transfer of energy from the primary to the secondary. It must direct the hot gases, plasma, electromagnetic radiation and neutrons toward the right place at the right time. Less than optimal interstage designs have resulted in the secondary failing to work entirely on multiple shots, known as a " fissile fizzle ". The Castle Koon shot of Operation Castle is a good example; a small flaw allowed

37840-519: 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

38055-519: 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

38270-537: 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 the third country to test nuclear weapons. The first Blue Danube atomic bombs were delivered to Bomber Command in November 1953, although

38485-412: The velocity at which the rest of the tamper implodes inwards. Applying the more detailed form of those calculations to the Ivy Mike device yields vaporized pusher gas expansion velocity of 290 kilometres per second (29 cm/μs) and an implosion velocity of perhaps 400 km/s (40 cm/μs) if + 3 ⁄ 4 of the total tamper/pusher mass is ablated off, the most energy efficient proportion. For

38700-404: The weapon (with the foam) would be as follows: This would complete the fission-fusion-fission sequence. Fusion, unlike fission, is relatively "clean"—it releases energy but no harmful radioactive products or large amounts of nuclear fallout . The fission reactions though, especially the last fission reactions, release a tremendous amount of fission products and fallout. If the last fission stage

38915-470: The year before. By 1968, the NSF budget stood at nearly $ 500 million. According to Marie Thorsten, Americans experienced a "techno-other void" after the Sputnik crisis and still express longing for "another Sputnik" to boost education and innovation. In the 1980s, the rise of Japan (both its car industry and its 5th generation computing project ) served to fan the fears of a "technology gap" with Japan. After

39130-500: The yield in large bombs, does not count as a "stage" in this terminology. The U.S. tested three-stage bombs in several explosions during Operation Redwing but is thought to have fielded only one such tertiary model, i.e., a bomb in which a fission stage, followed by a fusion stage, finally compresses yet another fusion stage. This U.S. design was the heavy but highly efficient (i.e., nuclear weapon yield per unit bomb weight) 25 Mt (100 PJ) B41 nuclear bomb . The Soviet Union

39345-731: Was a renewed interest in the existing Explorer program , which launched the first American satellite into orbit on January 31, 1958. In February 1958, Eisenhower authorized formation of the Advanced Research Projects Agency, which was later renamed to the Defense Advanced Research Projects Agency (DARPA), within the Department of Defense (DoD) to develop emerging technologies for the US military . On July 29, 1958, he signed

39560-529: 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

39775-410: 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

39990-407: Was after the people of the United States were exposed to a multitude of news reports that it became a "nation in shock". The media not only reported public concern but also created the hysteria. Journalists greatly exaggerated the danger of the Soviet satellite for their own benefit. On October 9, 1957, science fiction writer and scientist Arthur C. Clarke said that the day that Sputnik orbited around

40205-437: 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 the Prime Minister, who gave verbal approval, and

40420-562: 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 the growing UK fleet of nuclear submarines. The British ultimately acquired entire weapons systems, with

40635-600: 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

40850-405: 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

41065-486: Was calculated to be 73 × 10 ^   bar (7.3  TPa ) for the Ivy Mike design and 1,400 × 10 ^   bar (140  TPa ) for the W-80. Foam plasma pressure is the concept that Chuck Hansen introduced during the Progressive case, based on research that located declassified documents listing special foams as liner components within the radiation case of thermonuclear weapons. The sequence of firing

41280-447: 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

41495-401: 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

41710-563: 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,

41925-415: Was cut off by the United States at one point due to concerns about Soviet espionage. Full cooperation was not reestablished until an agreement governing the handling of secret information and other issues was signed. However, the British were allowed to observe the U.S. Castle tests and used sampling aircraft in the mushroom clouds , providing them with clear, direct evidence of the compression produced in

42140-530: Was derived had been shelved on the orders of Defense Secretary Charles Erwin Wilson amid interservice rivalry with the US Air Force 's PGM-17 Thor rocket. The Soviets used ICBM technology to launch Sputnik into space, which gave them two propaganda advantages over the US at once: the capability to send the satellite into orbit and proof of the distance capabilities of their missiles. That proved that

42355-498: Was discovered and developed by Sakharov and Yakov Zel'dovich in early 1954. Sakharov's "Third Idea", as the Teller–Ulam design was known in the USSR, was tested in the shot " RDS-37 " in November 1955 with a yield of 1.6 Mt (6.7 PJ). The Soviets demonstrated the power of the staging concept in October 1961, when they detonated the massive and unwieldy Tsar Bomba. It was the largest nuclear weapon developed and tested by any country. In 1954 work began at Aldermaston to develop

42570-534: 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

42785-421: 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

43000-509: Was impractical for a deployable weapon, and the next advance was to use a solid lithium deuteride fusion fuel instead. In 1954 this was tested in the " Castle Bravo " shot (the device was code-named Shrimp ), which had a yield of 15  Mt (63  PJ ) (2.5 times expected) and is the largest U.S. bomb ever tested. Efforts shifted towards developing miniaturized Teller–Ulam weapons that could fit into intercontinental ballistic missiles and submarine-launched ballistic missiles . By 1960, with

43215-451: 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

43430-411: Was learned to achieve a full-scale device within a year. The design of all modern thermonuclear weapons in the United States is known as the Teller–Ulam configuration for its two chief contributors, Edward Teller and Stanisław Ulam , who developed it in 1951 for the United States, with certain concepts developed with the contribution of physicist John von Neumann . Similar devices were developed by

43645-522: 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

43860-460: 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; the predicted yield had only been 1 megatonne of TNT (4.2 PJ). But it

44075-497: Was providing almost 10% of the federal funds for academic research. Further expansion was made in the funding and research of space weapons and missile defense in the form of anti-ballistic missile proposals. Education programs were initiated to foster a new generation of engineers and support was dramatically increased for scientific research. Congress increased the National Science Foundation (NSF) appropriation for 1959 to $ 134 million, almost $ 100 million higher than

44290-478: 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 the island. The physicists at Aldermaston had plenty of ideas about how to follow up Grapple X. Possibilities were discussed in September 1957. One

44505-450: 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

44720-402: 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

44935-409: 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

45150-449: 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

45365-405: 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 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

45580-562: 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

45795-435: 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 a major construction effort to improve

46010-411: Was used in the third test, but only produced approximately 150 kt (630 TJ). Sputnik crisis The Sputnik crisis was a period of public fear and anxiety in Western nations about the perceived technological gap between the United States and Soviet Union caused by the Soviets' launch of Sputnik 1 , the world's first artificial satellite . The crisis was a significant event in

46225-406: Was widely reported in other media. Five days after the launch of Sputnik 1 , the world's first artificial satellite, US President Dwight Eisenhower addressed the American people. After being asked by a reporter on security concerns about the Soviet satellite, Eisenhower said, "Now, so far as the satellite itself is concerned, that does not raise my apprehensions, not one iota." Eisenhower made

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