High Explosive Research (HER) was the British project to develop atomic bombs independently after the Second World War. This decision was taken by a cabinet sub-committee on 8 January 1947, in response to apprehension of an American return to isolationism, fears that Britain might lose its

great power A great power is a sovereign state that is recognized as having the ability and expertise to exert its influence on a global scale. Great powers characteristically possess military and economic strength, as well as diplomatic and soft power in ...

status, and the actions by the United States to withdraw unilaterally from sharing of nuclear technology under the 1943 Quebec Agreement. The decision was publicly announced in the

House of Commons The House of Commons is the name for the elected lower house of the bicameral parliaments of the United Kingdom and Canada. In both of these countries, the Commons holds much more legislative power than the nominally upper house of parliament. T ...

on 12 May 1948. HER was a civil project, not a military one. Staff were drawn from and recruited into the Civil Service, and were paid Civil Service salaries. It was headed by Lord Portal, as Controller of Production, Atomic Energy, in the Ministry of Supply. An Atomic Energy Research Establishment was located at a former airfield, Harwell, in Berkshire, under the direction of

John Cockcroft Sir John Douglas Cockcroft, (27 May 1897 – 18 September 1967) was a British physicist who shared with Ernest Walton the Nobel Prize in Physics in 1951 for splitting the atomic nucleus, and was instrumental in the development of nuclea ...

. The first nuclear reactor in the UK, a small

research reactor Research reactors are nuclear fission-based nuclear reactors that serve primarily as a neutron source. They are also called non-power reactors, in contrast to power reactors that are used for electricity production, heat generation, or marit ...

known as

GLEEP GLEEP, which stood for Graphite Low Energy Experimental Pile, was a long-lived experimental nuclear reactor in Oxfordshire, England. Run for the first time on August 15, 1947, it was the first reactor to operate in western Europe. It was built at ...

, went

critical Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine *Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in ...

at Harwell on 15 August 1947. British staff at the

Montreal Laboratory The Montreal Laboratory in Montreal, Quebec, Canada, was established by the National Research Council of Canada during World War II to undertake nuclear research in collaboration with the United Kingdom, and to absorb some of the scientists and ...

designed a larger reactor, known as BEPO, which went critical on 5 July 1948. They provided experience and expertise that would later be employed on the larger, production reactors. Production facilities were constructed under the direction of Christopher Hinton, who established his headquarters in a former Royal Ordnance Factory at Risley in

Lancashire Lancashire ( , ; abbreviated Lancs) is the name of a historic county, ceremonial county, and non-metropolitan county in North West England. The boundaries of these three areas differ significantly. The non-metropolitan county of Lancash ...

. These included a

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

metal plant at

Springfields Springfields is a nuclear fuel production installation in Salwick, near Preston in Lancashire, England (). The site is currently operated by Springfields Fuels Limited, under the management of Westinghouse Electric UK Limited, on a 150-year l ...

nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat fr ...

s and a

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...

processing plant at

Windscale Sellafield is a large multi-function nuclear site close to Seascale on the coast of Cumbria, England. As of August 2022, primary activities are nuclear waste storage, nuclear waste processing and storage and nuclear decommissioning. Former act ...

, and a

gaseous diffusion Gaseous diffusion is a technology used to produce enriched uranium by forcing gaseous uranium hexafluoride (UF6) through semipermeable membranes. This produces a slight separation between the molecules containing uranium-235 (235U) and uranium-2 ...

uranium enrichment Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238 ...

facility at Capenhurst, near Chester. The two Windscale reactors became operational in October 1950 and June 1951. The gaseous diffusion plant at Capenhurst began producing

highly enriched uranium Enriched uranium is a type of uranium in which the percent composition of uranium-235 (written 235U) has been increased through the process of isotope separation. Naturally occurring uranium is composed of three major isotopes: uranium-238 (238U ...

in 1954.

William Penney William George Penney, Baron Penney, (24 June 19093 March 1991) was an English mathematician and professor of mathematical physics at the Imperial College London and later the rector of Imperial College London. He had a leading role in the d ...

directed bomb design from

Fort Halstead Fort Halstead was a research site of Dstl, an executive agency of the UK Ministry of Defence. It is situated on the crest of the Kentish North Downs, overlooking the town of Sevenoaks, southeast of London. Originally constructed in 1892 as part ...

. In 1951 his design group moved to a new site at

Aldermaston Aldermaston is a village and civil parish in Berkshire, England. In the 2011 Census, the parish had a population of 1015. The village is in the Kennet Valley and bounds Hampshire to the south. It is approximately from Newbury, Basingsto ...

in Berkshire. The first British atomic bomb was successfully tested in

Operation Hurricane Operation Hurricane was the first test of a British atomic device. A plutonium implosion device was detonated on 3 October 1952 in Main Bay, Trimouille Island, in the Montebello Islands in Western Australia. With the success of Operation H ...

, during which it was detonated on board the frigate anchored off the

Monte Bello Islands The Montebello Islands, also rendered as the Monte Bello Islands, are an archipelago of around 174 small islands (about 92 of which are named) lying north of Barrow Island and off the Pilbara coast of north-western Australia. The islands f ...

in Australia on 3 October 1952. Britain thereby became the third country to test nuclear weapons, after the United States and the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

. The project concluded with the delivery of the first of its Blue Danube atomic bombs to

Bomber Command Bomber Command is an organisational military unit, generally subordinate to the air force of a country. The best known were in Britain and the United States. A Bomber Command is generally used for strategic bombing (although at times, e.g. during t ...

in November 1953, but British hopes of a renewed nuclear Special Relationship with the United States were frustrated. The technology had been superseded by the American development of the hydrogen bomb, which was first tested in November 1952, only one month after Operation Hurricane. Britain went on to develop its own hydrogen bombs, which it first tested in 1957. A year later, the United States and Britain resumed nuclear weapons cooperation.

Background

Tube Alloys

British Political Personalities 1936-1945 HU59483

The

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...

was discovered by

James Chadwick Sir James Chadwick, (20 October 1891 – 24 July 1974) was an English physicist who was awarded the 1935 Nobel Prize in Physics for his discovery of the neutron in 1932. In 1941, he wrote the final draft of the MAUD Report, which inspi ...

at the Cavendish Laboratory at the

University of Cambridge The University of Cambridge is a public collegiate research university in Cambridge, England. Founded in 1209 and granted a royal charter by Henry III in 1231, Cambridge is the world's third oldest surviving university and one of its most pr ...

in February 1932. In April 1932, his Cavendish colleagues

and

Ernest Walton Ernest Thomas Sinton Walton (6 October 1903 – 25 June 1995) was an Irish physicist and Nobel laureate. He is best known for his work with John Cockcroft to construct one of the earliest types of particle accelerator, the Cockcroft–Walton ...

split

lithium Lithium (from el, λίθος, lithos, lit=stone) is a chemical element with the symbol Li and atomic number 3. It is a soft, silvery-white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid ...

atoms with accelerated protons. Enrico Fermi and his team in Rome conducted experiments involving the bombardment of elements by slow neutrons, which produced heavier elements and

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

s. Then, in December 1938,

Otto Hahn Otto Hahn (; 8 March 1879 – 28 July 1968) was a German chemist who was a pioneer in the fields of radioactivity and radiochemistry. He is referred to as the father of nuclear chemistry and father of nuclear fission. Hahn and Lise Meitner ...

and

Fritz Strassmann Friedrich Wilhelm Strassmann (; 22 February 1902 – 22 April 1980) was a German chemist who, with Otto Hahn in December 1938, identified the element barium as a product of the bombardment of uranium with neutrons. Their observation was the ke ...

at Hahn's laboratory in

Berlin-Dahlem Dahlem ( or ) is a locality of the Steglitz-Zehlendorf borough in southwestern Berlin. Until Berlin's 2001 administrative reform it was a part of the former borough of Zehlendorf. It is located between the mansion settlements of Grunewald and ...

bombarded

with slowed neutrons, and discovered that barium had been produced, and therefore that the uranium

nucleus Nucleus ( : nuclei) is a Latin word for the seed inside a fruit. It most often refers to: *Atomic nucleus, the very dense central region of an atom * Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA Nucl ...

had been split. Hahn wrote to his colleague Lise Meitner, who, with her nephew Otto Frisch, developed a theoretical justification for the process, which they published in ''

Nature Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are ...

'' in 1939. 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. The term was already familiar to the British public through the writings of

H. G. Wells Herbert George Wells"Wells, H. G."
Revised 18 May 2015. ''

The World Set Free ''The World Set Free'' is a novel written in 1913 and published in 1914 by H. G. Wells. The book is based on a prediction of a more destructive and uncontrollable sort of weapon than the world has yet seen. It had appeared first in serialised ...

''.

George Paget Thomson Sir George Paget Thomson, FRS (; 3 May 189210 September 1975) was a British physicist and Nobel laureate in physics recognized for his discovery of the wave properties of the electron by electron diffraction. Education and early life Thomso ...

, at

Imperial College London Imperial College London (legally Imperial College of Science, Technology and Medicine) is a public research university in London, United Kingdom. Its history began with Prince Albert, consort of Queen Victoria, who developed his vision for a cu ...

, and

Mark Oliphant Sir Marcus Laurence Elwin Oliphant, (8 October 1901 – 14 July 2000) was an Australian physicist and humanitarian who played an important role in the first experimental demonstration of nuclear fusion and in the development of nuclear weapon ...

, an Australian physicist at the

University of Birmingham The University of Birmingham (informally Birmingham University) is a Public university, public research university located in Edgbaston, Birmingham, United Kingdom. It received its royal charter in 1900 as a successor to Queen's College, Birmingha ...

, were tasked with carrying out a series of experiments on uranium. By February 1940, Thomson's team had failed to create a chain reaction in natural uranium, and he had decided that it was not worth pursuing; but at Birmingham, Oliphant's team had reached a strikingly different conclusion. Oliphant had delegated the task to two German refugee scientists,

Rudolf Peierls Sir Rudolf Ernst Peierls, (; ; 5 June 1907 – 19 September 1995) was a German-born British physicist who played a major role in Tube Alloys, Britain's nuclear weapon programme, as well as the subsequent Manhattan Project, the combined Allie ...

and Frisch, who could not work on the university's secret projects like

radar Radar is a detection system that uses radio waves to determine the distance ('' ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, we ...

because they were

enemy alien In customary international law, an enemy alien is any native, citizen, denizen or subject of any foreign nation or government with which a domestic nation or government is in conflict and who is liable to be apprehended, restrained, secured and ...

s and therefore lacked the necessary security clearance. They calculated the

critical mass In nuclear engineering, a critical mass is the smallest amount of fissile material needed for a sustained nuclear chain reaction. The critical mass of a fissionable material depends upon its nuclear properties (specifically, its nuclear fi ...

of a metallic sphere of pure

uranium-235 Uranium-235 (235U or U-235) is an isotope of uranium making up about 0.72% of natural uranium. Unlike the predominant isotope uranium-238, it is fissile, i.e., it can sustain a nuclear chain reaction. It is the only fissile isotope that exi ...

, and found that instead of tons, as everyone had assumed, as little as would suffice, which would explode with the power of thousands of tons of dynamite. Oliphant took the Frisch–Peierls memorandum to Sir

Henry Tizard Sir Henry Thomas Tizard (23 August 1885 – 9 October 1959) was an English chemist, inventor and Rector of Imperial College, who developed the modern "octane rating" used to classify petrol, helped develop radar in World War II, and led the fir ...

, the chairman of the

Tizard Committee The Committee for the Scientific Survey of Air Defence (CSSAD), also known as the Tizard Committee after its chairman, Henry Tizard, was a pre-World War II scientific mission to study the needs of anti-aircraft warfare in the United Kingdom. The ...

, and the

MAUD Committee The MAUD Committee was a British scientific working group formed during the Second World War. It was established to perform the research required to determine if an atomic bomb was feasible. The name MAUD came from a strange line in a telegram fro ...

was established to investigate further. It directed an intensive research effort, and in July 1941, produced two comprehensive reports that concluded an atomic bomb was not only technically feasible, but could be produced before the war ended, perhaps in as little as two years. The Committee unanimously recommended pursuing the development of an atomic bomb as a matter of urgency, although it recognised that the resources required might be beyond those available to Britain. A new directorate known by the deliberately misleading name of

Tube Alloys Tube Alloys was the research and development programme authorised by the United Kingdom, with participation from Canada, to develop nuclear weapons during the Second World War. Starting before the Manhattan Project in the United States, the ...

was created to coordinate this effort. Sir John Anderson, the Lord President of the Council, became the minister responsible, and

Wallace Akers Sir Wallace Alan Akers (9 September 1888 – 1 November 1954) was a British chemist and industrialist. Beginning his academic career at Oxford he specialized in physical chemistry. During the Second World War, he was the director of the Tube Al ...

from Imperial Chemical Industries (ICI) was appointed the director of Tube Alloys.

Manhattan Project

In July 1940, Britain had offered to give the United States access to its scientific research, and Cockcroft, as part of the

Tizard Mission The Tizard Mission, officially the British Technical and Scientific Mission, was a British delegation that visited the United States during WWII to obtain the industrial resources to exploit the military potential of the research and development ( ...

, briefed American scientists on British developments. He discovered that the American project was smaller than the British, and not as far advanced. The British and American projects exchanged information, but did not initially combine their efforts. British officials did not reply to an August 1941 American offer to create a combined project. In November 1941, Frederick L. Hovde, the head of the London liaison office of the American

Office of Scientific Research and Development The Office of Scientific Research and Development (OSRD) was an agency of the United States federal government created to coordinate scientific research for military purposes during World War II. Arrangements were made for its creation during May 1 ...

(OSRD), raised the issue of cooperation and exchange of information with Anderson and Lord Cherwell, who demurred, ostensibly over concerns about American security. Ironically, it was the British project that had already been penetrated by

atomic spies Atomic spies or atom spies were people in the United States, the United Kingdom, and Canada who are known to have illicitly given information about nuclear weapons production or design to the Soviet Union during World War II and the early ...

for the

The United Kingdom did not have the manpower or resources of the United States, and despite its early and promising start, Tube Alloys fell behind its American counterpart and was dwarfed by it. On 30 July 1942, Anderson advised the Prime Minister,

Winston Churchill Sir Winston Leonard Spencer Churchill (30 November 187424 January 1965) was a British statesman, soldier, and writer who served as Prime Minister of the United Kingdom twice, from 1940 to 1945 during the Second World War, and again from ...

, that: "We must face the fact that ... urpioneering work ... is a dwindling asset and that, unless we capitalise it quickly, we shall be outstripped. We now have a real contribution to make to a 'merger.' Soon we shall have little or none." The British considered producing an atomic bomb without American help, but the project would have needed overwhelming priority, the projected cost was staggering, 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. The unanimous response was that before embarking on this, another effort should be made to secure American cooperation. At the Quadrant Conference in August 1943, Churchill and the American President, Franklin Roosevelt, signed the Quebec Agreement, which merged the two national projects. Its terms made it clear that Britain was the junior partner in the Grand Alliance. The British considered the Quebec Agreement to be the best deal they could have struck under the circumstances, and the restrictions were the price they had to pay to obtain the technical information needed for a successful post-war nuclear weapons project.

Margaret Gowing Margaret Mary Gowing (), (26 April 1921 – 7 November 1998) was an English historian. She was involved with the production of several volumes of the officially sponsored ''History of the Second World War'', but was better known for her books ...

noted that the "idea of the independent deterrent was already well entrenched." The Quebec Agreement established the Combined Policy Committee and the Combined Development Trust to coordinate their efforts. The 19 September 1944 Hyde Park Aide-Mémoire extended both commercial and military cooperation into the post-war period. A British mission led by Akers assisted in the development of

technology at the SAM Laboratories in New York. Another, led by Oliphant, who acted as deputy director at the Berkeley Radiation Laboratory, assisted with the

electromagnetic separation Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" n ...

process. Cockcroft became the director of the Anglo-Canadian

. The British mission to the

Los Alamos Laboratory The Los Alamos Laboratory, also known as Project Y, was a secret laboratory established by the Manhattan Project and operated by the University of California during World War II. Its mission was to design and build the first atomic bombs. Ro ...

led by

, and later Peierls, included distinguished scientists such as Geoffrey Taylor, James Tuck,

Niels Bohr Niels Henrik David Bohr (; 7 October 1885 – 18 November 1962) was a Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922 ...

, Frisch, Ernest Titterton and Klaus Fuchs, who was later revealed to be a Soviet spy. As overall head of the British Mission, Chadwick forged a close and successful partnership with

Brigadier General Brigadier general or Brigade general is a military rank used in many countries. It is the lowest ranking general officer in some countries. The rank is usually above a colonel, and below a major general or divisional general. When appointed ...

Leslie R. Groves, the director of the Manhattan Project. He ensured that British participation was complete and wholehearted.

End of American cooperation

With the end of the war the Special Relationship between Britain and the United States "became very much less special". The British government had trusted that America would share nuclear technology, which it considered a joint discovery. On 8 August 1945 the Prime Minister, Clement Attlee, sent a message to President

Harry Truman Harry S. Truman (May 8, 1884December 26, 1972) was the 33rd president of the United States, serving from 1945 to 1953. A leader of the Democratic Party, he previously served as the 34th vice president from January to April 1945 under Franklin ...

in which he referred to themselves as "heads of the Governments which have control of this great force". Roosevelt had died on 12 April 1945, and the Hyde Park Aide-Mémoire was not binding on subsequent administrations. In fact, the American copy was temporarily physically lost. When Field Marshal

Henry Maitland Wilson Field Marshal Henry Maitland Wilson, 1st Baron Wilson, (5 September 1881 – 31 December 1964), also known as Jumbo Wilson, was a senior British Army officer of the 20th century. He saw active service in the Second Boer War and then during the ...

raised the matter in a Combined Policy Committee meeting in June, the American copy could not be found. The British sent

Secretary of War The secretary of war was a member of the U.S. president's Cabinet, beginning with George Washington's administration. A similar position, called either "Secretary at War" or "Secretary of War", had been appointed to serve the Congress of the ...

Henry L. Stimson Henry Lewis Stimson (September 21, 1867 – October 20, 1950) was an American statesman, lawyer, and Republican Party politician. Over his long career, he emerged as a leading figure in U.S. foreign policy by serving in both Republican and D ...

a photocopy on 18 July 1945. Even then, Groves questioned the document's authenticity until the American copy was located years later in the papers of Vice Admiral Wilson Brown Jr., Roosevelt's naval aide, apparently misfiled by someone unaware of what Tube Alloys was, and thought it had something to do with naval guns. On 9 November 1945, Attlee and the

Prime Minister of Canada The prime minister of Canada (french: premier ministre du Canada, link=no) is the head of government of Canada. Under the Westminster system, the prime minister governs with the confidence of a majority the elected House of Commons; as su ...

, 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 the Quebec Agreement. It made Canada a full partner; continued the Combined Policy Committee and Combined Development Trust; and reduced the obligation to obtain consent for the use of nuclear weapons to merely requiring consultation. The three leaders agreed that there would be full and effective cooperation on atomic energy, but British hopes for a resumption of cooperation on nuclear energy were disappointed. The Americans soon made it clear that cooperation was restricted to basic scientific research. The next meeting of the Combined Policy Committee on 15 April 1946 produced no accord on collaboration, and resulted in an exchange of cables between Truman and Attlee. Truman cabled on 20 April that he did not see the communiqué he had signed as obligating the United States to assist Britain in designing, constructing and operating an atomic energy plant. The passing of the Atomic Energy Act of 1946 (McMahon Act) in August 1946, which was signed by Truman on 1 August 1946, and went into effect at midnight on 1 January 1947, ended technical cooperation. Its control of "restricted data" prevented the United States' allies from receiving any information. This partly resulted from the arrest for espionage of British physicist

Alan Nunn May Alan Nunn May (sometimes Allan) (2 May 1911 – 12 January 2003) was a British physicist and a confessed and convicted Soviet spy who supplied secrets of British and American atomic research to the Soviet Union during World War II. Early li ...

, who had worked in the Montreal Laboratory, in February 1946, while the legislation was being debated. The remaining British scientists working in the United States were denied access to papers that they had written just days before.

Resumption of independent UK efforts

Organisation

Attlee had created a cabinet sub-committee, the

Gen 75 Committee The Gen 75 Committee was a committee of the British cabinet, convened by the Prime Minister, Clement Attlee, on 10 August 1945. It was one of many ''ad hoc'' cabinet committees, each of which was convened to handle a single issue, and given a ...

(known informally by Attlee as the "Atomic Bomb Committee"), on 10 August 1945 to examine the feasibility of a nuclear weapons programme. To provide technical advice, Attlee created an Advisory Committee on Atomic Energy, with Anderson as its chairman. Anderson was an

independent Independent or Independents may refer to: Arts, entertainment, and media Artist groups * Independents (artist group), a group of modernist painters based in the New Hope, Pennsylvania, area of the United States during the early 1930s * Independ ...

Member of Parliament A member of parliament (MP) is the representative in parliament of the people who live in their electoral district. In many countries with bicameral parliaments, this term refers only to members of the lower house since upper house members o ...

for the

Scottish Universities There are fifteen universities in Scotland and three other institutions of higher education that have the authority to award academic degrees. The first university college in Scotland was founded at St John's College, St Andrews in 1418 by H ...

who sat on the Opposition Front Bench. As chairman of the Advisory Committee on Atomic Energy, Anderson had his own office in the Cabinet Office, and the services of its secretariat. He accompanied Attlee on his November 1945 trip to the United States. A 2September 1945

Admiralty Admiralty most often refers to: *Admiralty, Hong Kong *Admiralty (United Kingdom), military department in command of the Royal Navy from 1707 to 1964 *The rank of admiral *Admiralty law Admiralty can also refer to: Buildings * Admiralty, Traf ...

study of "The Influence of the Atomic Bomb on War" forecast that an enemy could build 500 bombs during ten years of peace, and warned that if 10 per cent of the arsenal was used on the United Kingdom, "over night the main base of the British Empire could be rendered ineffective", with enough left for other British forces around the world. In October 1945, the Gen 75 Committee considered the issue of ministerial responsibility for atomic energy. The Cabinet Secretary, Sir Edward Bridges, and the Advisory Committee on Atomic Energy both recommended that it be placed within the Ministry of Supply. Developing atomic energy would require an enormous construction effort, which the Ministry of Supply was best equipped to undertake. The Tube Alloys Directorate was transferred from the

Department of Scientific and Industrial Research Department of Scientific and Industrial Research, abbreviated DSIR was the name of several British Empire organisations founded after the 1923 Imperial Conference to foster intra-Empire trade and development. * Department of Scientific and Industria ...

to the Ministry of Supply effective 1 November 1945. To coordinate the atomic energy effort, it was decided to appoint a Controller of Production, Atomic Energy (CPAE). The

Minister of Supply The Minister of Supply was the minister in the British Government responsible for the Ministry of Supply, which existed to co-ordinate the supply of equipment to the national armed forces. The position was campaigned for by many sceptics of the for ...

John Wilmot John Wilmot, 2nd Earl of Rochester (1 April 1647 – 26 July 1680) was an English poet and courtier of King Charles II's Restoration court. The Restoration reacted against the "spiritual authoritarianism" of the Puritan era. Rochester embodi ...

, suggested

Marshal of the Royal Air Force Marshal of the Royal Air Force (MRAF) is the highest rank in the Royal Air Force (RAF). In peacetime it was granted to RAF officers in the appointment of Chief of the Defence Staff (CDS), and to retired Chiefs of the Air Staff (CAS), who were ...

Lord Portal, the wartime Chief of the Air Staff. Portal was reluctant to accept the post, as he felt that he lacked administrative experience outside the

Royal Air Force The Royal Air Force (RAF) is the United Kingdom's air and space force. It was formed towards the end of the First World War on 1 April 1918, becoming the first independent air force in the world, by regrouping the Royal Flying Corps (RFC) an ...

, but eventually accepted it for a two-year term, commencing in March 1946. In this role he had direct access to the Prime Minister. Portal ran the project until 1951, when he was succeeded by Sir Frederick Morgan. He established his headquarters at

Shell Mex House Shell Mex House, also known as 80 Strand, is a grade II listed building located at number 80 Strand in London, England. The building was opened in 1932 on the site of the Hotel Cecil and stands behind the original façade of the hotel, between ...

on the Strand, London, where the wartime Tube Alloys had been. Special security barriers were installed to close off this section of the offices, giving the area the nickname "the Cage". John Douglas Cockcroft 1961

With Portal's appointment came consideration of splitting Anderson's committee, which functioned as both an advisory and an interdepartmental body. In August 1946, a new standing committee was created, the Atomic Energy Official Committee, which assumed the interdepartmental function. In March 1947, Roger Makins became its chairman. Anderson's committee declined in influence, and was disbanded when he departed at the end of 1947. During the war, Christopher Hinton had been seconded from ICI to the Ministry of Supply and had become Deputy Director General of

Filling Factories A filling factory was a manufacturing plant that specialised in filling various munitions, such as bombs, shells, cartridges, pyrotechnics, and screening smokes. In the United Kingdom, during both world wars of the 20th century, the majority of ...

. He was due to return to ICI at the end 1945, but agreed to oversee the design, construction and operation of the new facilities at a salary far below that offered by ICI. He established his headquarters in a former Royal Ordnance Factory at Risley in

on 4 February 1946. Portal also created a position of Deputy Controller (Technical Policy), to which he appointed Michael Perrin. This created ill-feeling, as Perrin had been junior to Hinton at ICI. Portal also created a Technical Committee to replace the old Tube Alloys Technical Committee. To give the Ministry of Supply's control over atomic energy a legal form, a bill was introduced into the

on 1 May 1946 that became law as the

Atomic Energy Act 1946 Atomic may refer to: * Of or relating to the atom, the smallest particle of a chemical element that retains its chemical properties * Atomic physics, the study of the atom * Atomic Age, also known as the "Atomic Era" * Atomic scale, distances comp ...

on 6 November 1946. During the war, Chadwick, Cockcroft, Oliphant, Peierls,

Harrie Massey Sir Harrie Stewart Wilson Massey (16 May 1908 – 27 November 1983) was an Australian mathematical physicist who worked primarily in the fields of atomic and atmospheric physics. A graduate of the University of Melbourne and Cambridge Unive ...

and Herbert Skinner had met in Washington, D.C., in November 1944, and drawn up a proposal for a British atomic energy research establishment, which they had calculated would cost around £1.5 million. The Tube Alloys Committee endorsed their recommendation in April 1945, and Attlee announced its creation in the House of Commons on 29 October 1945, informing the House that it would cost about £1 million to build and £500,000 per annum to run. The obvious choices for a director of the new establishment were Chadwick and Cockcroft, and the former urged that the latter be appointed. Cockcroft agreed, subject to stipulation in writing that he would be answerable only to the Minister and his Permanent Secretary, and, except where subject to requirements for military secrecy, the establishment would be run like a university, with free exchange of views and the publication of papers. His appointment was announced in November 1945, although he did not leave Canada until September 1946. The Atomic Energy Research Establishment (AERE) did not come under Portal's control until January 1950. A committee selected a site for the AERE at RAF Harwell, an airfield about south of

Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...

. The airfield was a modern one, with a long runway, and the

Air Ministry The Air Ministry was a department of the Government of the United Kingdom with the responsibility of managing the affairs of the Royal Air Force, that existed from 1918 to 1964. It was under the political authority of the Secretary of State ...

was reluctant to release it until the Prime Minister intervened. Responsibility for the development of atomic bombs lay outside the realm of the Ministry of Defence. One reason for this was that it was only created in October 1946, by which time Portal had already been appointed as CPAE. Tizard became the

Chief Scientific Adviser to the Ministry of Defence The Chief Scientific Adviser to the UK's Ministry of Defence is responsible for providing strategic management of science and technology issues in the MOD, most directly through the MOD research budget of well over £1 billion, and sits as a full me ...

in November 1946, and in January 1947 he also became the chairman of the

Defence Research Policy Committee The Defence Research Policy Committee, or DRPC, was a British Cabinet-level standing committee formed in 1947 that advised and directed military research in the United Kingdom. It was the equivalent of the US's National Defense Research Committee or ...

(DRPC), which was established to advise the Minister of Defence and the Chiefs of Staff on matters of scientific policy. Tizard attempted to gain some control over nuclear weapons policy. Anderson's advisory committee was abolished at the end of 1947, and two new committees were established in its place, the Atomic Energy (Defence Research) Committee AE(DR), which came under the DRPC, and was chaired by Tizard; and the Atomic Energy (Review of Production) Committee, which was answerable to Portal. But Tizard failed to gain control of atomic energy policy.

Decision

An early debate among the scientists was whether the fissile material for an atomic bomb should be uranium-235 or

. Tube Alloys had performed much of the pioneering research on gaseous diffusion for

, and Oliphant's team in Berkeley were well-acquainted with the electromagnetic process. The staff that had remained in Britain strongly favoured uranium-235; but the scientists that had worked in the United States argued for plutonium on the basis of its greater efficiency as an explosive, despite the fact that they had neither the expertise in the design of

s to produce it, nor the requisite knowledge of plutonium chemistry or metallurgy to extract it. However, the Montreal Laboratory had designed and was building pilot reactors, and had carried out some work on separating plutonium from uranium. The Manhattan Project had pursued both avenues, and the scientists who had worked at Los Alamos were aware of work there with composite cores that used both; but there were concerns that Britain might not have the money, resources or skilled manpower for this. In the end, it came down to economics; a reactor could be built more cheaply than a separation plant that produced an equivalent quantity of enriched uranium, and made more efficient use of uranium fuel. A reactor and separation plant capable of producing enough plutonium for fifteen bombs per year was costed at around £20 million. The facility was approved by the Gen 75 committee on 18 December 1945 "with the highest urgency and importance". Bevin Attlee H 42138

A few months later, Portal, who had not been appointed when this decision was taken, began to have doubts. Word reached him of problems with the

Hanford Site The Hanford Site is a decommissioned nuclear production complex operated by the United States federal government on the Columbia River in Benton County in the U.S. state of Washington. The site has been known by many names, including SiteW a ...

reactors, which had been all but completely shut down due to Wigner's disease. On a visit to the United States in May 1946, Groves advised Portal not to build a reactor. By this time, there was interest from the scientists in making better use of uranium fuel by re-enrichment of spent fuel rods. A gaseous diffusion plant was costed at somewhere between £30 and £40 million. The Gen 75 Committee considered the proposal in October 1946. Perrin, who was present, later recalled that: Penney had joined the Los Alamos Laboratory in 1944, and had served on the Target Committee that had selected cities to be attacked. He had been in the observation plane '' Big Stink'' during the

bombing of Nagasaki The United States detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki on 6 and 9 August 1945, respectively. The two bombings killed between 129,000 and 226,000 people, most of whom were civilians, and remain the on ...

, and had done damage assessment on the ground following Japan's surrender. He had returned to England in November 1945 intending to resume his academic career, but was approached by

C. P. Snow Charles Percy Snow, Baron Snow, (15 October 1905 – 1 July 1980) was an English novelist and physical chemist who also served in several important positions in the British Civil Service and briefly in the UK government.''The Columbia Encyclope ...

, one of the Civil Service Commissioners, and asked to become Chief Superintendent Armament Research (CSAR, pronounced "Caesar"), in charge of the Ministry of Supply's Armaments Research Department (ARD) at

in Kent. His appointment as CSAR was announced on 1 January 1946, but Groves asked him to assist in the American

Operation Crossroads Operation Crossroads was a pair of nuclear weapon tests conducted by the United States at Bikini Atoll in mid-1946. They were the first nuclear weapon tests since Trinity in July 1945, and the first detonations of nuclear devices since the ...

nuclear tests at

Bikini Atoll Bikini Atoll ( or ; Marshallese: , , meaning "coconut place"), sometimes known as Eschscholtz Atoll between the 1800s and 1946 is a coral reef in the Marshall Islands consisting of 23 islands surrounding a central lagoon. After the Seco ...

. Penney left for the United States in March 1946, and did not return to Britain until October 1946. Portal then asked him to draw up a scheme for an Atomic Weapons Section within the Armaments Research Department which would design, develop and construct atomic bombs. In his 1 November 1946 report to Portal, which he had to type himself for security reasons, Penney provided a proposed organisation chart, detailed his staffing requirements, and listed his accommodation requirements, which he felt could be met at Fort Halstead, the Royal Arsenal at

Woolwich Woolwich () is a district in southeast London, England, within the Royal Borough of Greenwich. The district's location on the River Thames led to its status as an important naval, military and industrial area; a role that was maintained thr ...

, and Shoeburyness. William Penney

In July 1946, the

Chiefs of Staff Committee The Chiefs of Staff Committee (CSC) is composed of the most senior military personnel in the British Armed Forces who advise on operational military matters and the preparation and conduct of military operations. The committee consists of the C ...

considered the issue of nuclear weapons, and recommended that Britain acquire them. This recommendation was accepted by the Cabinet Defence Committee on 22 July 1946. The Chief of the Air Staff, Lord Tedder, officially requested an atomic bomb on 9 August 1946. The Chiefs of Staff estimated that 200 bombs would be required by 1957. Despite this, and the research and construction of facilities that had already been approved, there was still no official decision to proceed with making atomic bombs. Portal submitted his proposal to do so at the 8 January 1947 meeting of the Gen 163 Committee, another ''ad hoc'' committee, which agreed to proceed with the development of atomic bombs. It also endorsed Portal's proposal to place Penney in charge of the bomb development effort, although Penney was not informed of this decision until May. Of the decision,

wrote: This represented deep-rooted British political and strategic ideas. The war had left Britain impoverished. Its gold and dollar reserves had been depleted. A third of its merchant ships now lay on the bottom of the ocean. About 250,000 homes had been destroyed and another 3 million had been damaged while hardly any had been built for years. In early 1947, factories suspended production for want of coal. The United States had abruptly terminated Lend-Lease when the war ended. In its place was a $3.75 billion loan from the United States and a $1.25 billion loan from Canada, most of which had been spent by August 1947. Nonetheless, there remained an implacable belief that the future would be like the past. Bevin told the House of Commons on 16 May 1947 that: In his 1961 memoirs, Attlee explained his decision: The decision was publicly announced in the House of Commons on 12 May 1948 by the

Minister of Defence A defence minister or minister of defence is a cabinet official position in charge of a ministry of defense, which regulates the armed forces in sovereign states. The role of a defence minister varies considerably from country to country; in som ...

, Albert Alexander, albeit in an oblique answer to a pre-arranged question from

George Jeger George Jeger (19 March 1903 – 6 January 1971) was a British Labour Party politician. He served as the Member of Parliament for Winchester from 1945 to 1950 (which after his term became a safe seat for the Conservatives until they lost it to t ...

, a Labour Party backbencher.

D notice In the United Kingdom, a DSMA-Notice (Defence and Security Media Advisory Notice) is an official request to news editors not to publish or broadcast items on specified subjects for reasons of national security. DSMA-Notices were formerly called a ...

No. 25 prohibited the publication of details on the design, construction or location of atomic weapons. The project was hidden under the cover name "Basic High Explosive Research". "Basic" was soon dropped and it became simply "High Explosive Research" (HER).

Uranium

Uranium was the only known fuel for nuclear reactors, so securing an adequate supply was crucial to the British atomic energy programme. During the war, Britain took the lead in reopening the world's richest uranium mine, the

Shinkolobwe Shinkolobwe, or Kasolo, or Chinkolobew, or Shainkolobwe, was a radium and uranium mine in the Haut-Katanga Province of the Democratic Republic of the Congo (DRC), located 20 km west of Likasi (formerly Jadotville), 20 km south of Kamb ...

mine in the

Belgian Congo The Belgian Congo (french: Congo belge, ; nl, Belgisch-Congo) was a Belgian colony in Central Africa from 1908 until independence in 1960. The former colony adopted its present name, the Democratic Republic of the Congo (DRC), in 1964. Colo ...

, which had been flooded and closed, as 30 per cent of the stock in

Union Minière du Haut Katanga Union commonly refers to: * Trade union, an organization of workers * Union (set theory), in mathematics, a fundamental operation on sets Union may also refer to: Arts and entertainment Music * Union (band), an American rock group ** ''Un ...

, the company that owned the mine, was controlled by British interests. In May 1944, Sir John Anderson and US Ambassador

John Winant John Gilbert Winant (February 23, 1889 – November 3, 1947) was an American diplomat and politician with the Republican party after a brief career as a teacher in Concord, New Hampshire. John Winant held positions in New Hampshire, national, an ...

negotiated a deal with the

Belgian government in exile The Belgian Government in London (french: Gouvernement belge à Londres, nl, Belgische regering in Londen), also known as the Pierlot IV Government, was the government in exile of Belgium between October 1940 and September 1944 during World W ...

and

Edgar Sengier Edgar Edouard Bernard Sengier (9 October 1879 – 26 July 1963) was a Belgian mining engineer and director of the Union Minière du Haut Katanga mining company that operated in Belgian Congo during World War II. Sengier is credited with ...

, the director of Union Minière, for the mine to be reopened and of ore to be purchased at $1.45 a pound. American and British leaders concluded that it was in their best interest to gain control of as much of the world's uranium deposits as possible. The Combined Development Trust was established for this purpose on 14 June 1944. It consisted of three American, two British and one Canadian members, with an American, initially Groves, as chairman. By the end of the war, it had control of 97 per cent of the world's uranium and 65 per cent of the

thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...

During the war, all the uranium from the Congo had gone to the United States, as had that captured in Europe by the

Alsos Mission The Alsos Mission was an organized effort by a team of British and United States military, scientific, and intelligence personnel to discover enemy scientific developments during World War II. Its chief focus was on the German nuclear energy pro ...

, even though some of it passed through British hands. The entire output of the Shinkolobwe mine was contracted to the Combined Development Trust until 1956, but in March 1946 there were fears that the mine might be exhausted in 1947, resulting in a severe uranium shortage. After some negotiation, Groves and Chadwick agreed on a division of uranium ore production, with everything up to March 1946 going to the United States, and supplies being shared equally thereafter. At the Combined Policy Committee meeting on 31 July 1946, the financial arrangements were adjusted. Previously, the two countries had split the costs equally; henceforth each would pay for only what they actually received. Britain was therefore able to secure the uranium it needed without having to outbid the United States, and paid for it in sterling. Meanwhile, because the adjustment applied retrospectively to VJ Day, it received reimbursement for the supplies allocated to the United States, thus easing Britain's dollar shortage. By the end of 1946, Britain had received , and another 500 was stockpiled for the Trust at

, near Preston in Lancashire. Uranium ore was stockpiled in Britain because the McMahon Act did not permit it to be exported from the United States. Groves extended the arrangement into 1947, and another was shipped to Britain, all of which was added to the Springfields stockpile. Its growing size was the principal reason the Americans reopened the negotiations resulting in the ''Modus Vivendi'', which allowed for limited sharing of technical information between the United States, Britain and Canada. Under this agreement, all the Congo ore from 1948 and 1949 was shipped to the United States. The Trust was renamed the Combined Development Agency in January 1948. The first Soviet atomic bomb test in August 1949 was embarrassing to the British (who had not expected a Soviet atomic weapon until 1954) for having been beaten, but it was for the Americans another reason for cooperation. The agreement on raw materials was due to expire at the end of the year. The Americans offered to make bombs in the United States available for Britain to use if the British agreed to end their atomic bomb programme. This offer was rejected on the grounds that it was not "compatible with our status as a first class power to depend on others for weapons of this supreme importance." Instead, the British suggested that there would be a full exchange of atomic information, and in return for ending the production of atomic bombs in Britain, American bombs would be stored in Britain under British control. This would have given Britain nuclear weapons much sooner than its own target date of late 1952. The opposition of several key officials, including the

United States Atomic Energy Commission The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President ...

Lewis Strauss Lewis Lichtenstein Strauss ( "straws"; January 31, 1896January 21, 1974) was an American businessman, philanthropist, and naval officer who served two terms on the U.S. Atomic Energy Commission (AEC), the second as its chairman. He was a major ...

, and Senators Bourke B. Hickenlooper and

Arthur Vandenberg Arthur Hendrick Vandenberg Sr. (March 22, 1884April 18, 1951) was an American politician who served as a United States senator from Michigan from 1928 to 1951. A member of the Republican Party, he participated in the creation of the United Natio ...

, coupled with security concerns aroused by the 2 February 1950 arrest of Fuchs, who was working at Harwell, as a Soviet spy, caused the proposal to be rejected. By this time, most of the original allocated to Britain had been used up, and the Americans agreed to allocate from the Springfields stockpile. Britain was allocated a further in 1951, and in 1952. Due to increased production, and the discovery and development of new sources of uranium in Portugal, South Africa and Australia, there was sufficient uranium for the United States, British and Canadian programmes, although Britain had to cancel a reactor in 1949.

Production facilities

Between January 1946 and March 1953, £44 million was spent on constructing nuclear weapons facilities. Staff were drawn from and recruited into the Civil Service, and were paid Civil Service salaries.

Uranium metal plant

During the war, Chadwick had arranged for ICI to build a small plant to produce uranium. By 1947, it was operational and producing per week. This would be used in BEPO, the experimental reactor built at Harwell, but the plant required

uranium oxide Uranium oxide is an oxide of the element uranium. The metal uranium forms several oxides: * Uranium dioxide or uranium(IV) oxide (UO2, the mineral uraninite or pitchblende) * Diuranium pentoxide or uranium(V) oxide (U2O5) * Uranium trioxide o ...

feed, and the export of this from the United States was banned under the McMahon Act. Hinton and his staff at Risley built a new uranium plant at Springfields, on the site of a former poison gas plant, at a cost of £5.5 million. The first uranium metal was produced in October 1948. Uranium ore was crushed and dissolved in acids. Impurities were separated and uranium oxide was precipitated. Radium was returned to Union Minière under the contract with the company. The uranium oxide was then purified. It was dissolved in

nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available nitri ...

to produce

uranyl nitrate Uranyl nitrate is a water-soluble yellow uranium salt with the formula . The hexa-, tri-, and dihydrates are known. The compound is mainly of interest because it is an intermediate in the preparation of nuclear fuels. Uranyl nitrate can be prepa ...

. This was then dissolved in

ether In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups. They have the general formula , where R and R′ represent the alkyl or aryl groups. Ethers can again be ...

, drawn off and precipitated by the addition of ammonia, producing ammonium diuranate. The ammonium diuranate was heated in a furnace and reduced with hydrogen and hydrofluoric acid to produce

uranium tetrafluoride Uranium tetrafluoride is the inorganic compound with the formula UF4. It is a green solid with an insignificant vapor pressure and low solubility in water. Uranium in its tetravalent ( uranous) state is important in various technological process ...

. Heating and mixing with calcium metal reduced it to metallic uranium, leaving

calcium fluoride Calcium fluoride is the inorganic compound of the elements calcium and fluorine with the formula CaF2. It is a white insoluble solid. It occurs as the mineral fluorite (also called fluorspar), which is often deeply coloured owing to impurities. ...

behind as a slag. The metallic uranium was then cast into

billets A billet is a living-quarters to which a soldier is assigned to sleep. Historically, a billet was a private dwelling that was required to accept the soldier. Soldiers are generally billeted in barracks or garrisons when not on combat duty, al ...

. These were extruded into rods and sealed in

aluminium Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. I ...

cans.

Nuclear reactors

The first nuclear reactor in the UK, a small 100 kW

known as

, went

at Harwell on 15 August 1947. It was fuelled by of uranium metal and of uranium dioxide, and used of

nuclear graphite Nuclear graphite is any grade of graphite, usually synthetic graphite, manufactured for use as a moderator or reflector within a nuclear reactor. Graphite is an important material for the construction of both historical and modern nuclear reactor ...

as a neutron moderator. This was fine for some experimental work, but the production of radioactive isotopes required a more powerful 6,000 kW reactor with a higher

neutron flux The neutron flux, φ, is a scalar quantity used in nuclear physics and nuclear reactor physics. It is the total length travelled by all free neutrons per unit time and volume. Equivalently, it can be defined as the number of neutrons travellin ...

. British staff at the Montreal Laboratory had designed BEPO in 1945 and 1946; Risley handled the engineering and construction. The key choices in reactor design are the selection of the fuel, the neutron moderator, and the coolant. Since enriched uranium was unavailable, the only available fuel was natural uranium. Similarly, while the Montreal Laboratory had experience with designing and building the

ZEEP The ZEEP (Zero Energy Experimental Pile) reactor was a nuclear reactor built at the Chalk River Laboratories near Chalk River, Ontario, Canada (which superseded the Montreal Laboratory for nuclear research in Canada). ZEEP first went critical a ...

heavy-water reactor A pressurized heavy-water reactor (PHWR) is a nuclear reactor that uses heavy water ( deuterium oxide D2O) as its coolant and neutron moderator. PHWRs frequently use natural uranium as fuel, but sometimes also use very low enriched uranium. T ...

in Canada, no heavy water was available in the UK, so graphite was the only choice for a neutron moderator. That left cooling, and for an experimental reactor, air cooling was the obvious choice. The resulting reactor was thus quite similar to the American X-10 Graphite Reactor. BEPO, which went critical on 5 July 1948, used of metallic uranium and of graphite, encased in of steel and of concrete. Storm Clouds over Sellafield - geograph

For the plutonium-producing production reactors, the same reasons mandated the use of natural uranium fuel and graphite as a moderator; but it was originally assumed that they would be water-cooled like the American reactors at the Hanford Site. A water-cooled reactor of the required size would require about of water per day, preferably very pure so as to avoid corroding the metal pipes. Moreover, there were concerns about safety. Water absorbs neutrons, so if there is a sudden loss of cooling water this will result in an increase in the neutron flux and the reactor temperature, and possibly a catastrophic

nuclear meltdown A nuclear meltdown (core meltdown, core melt accident, meltdown or partial core melt) is a severe nuclear reactor accident that results in core damage from overheating. The term ''nuclear meltdown'' is not officially defined by the Internatio ...

. Such an event did indeed occur in the Chernobyl disaster in 1986. The American solution was to locate the facility in a remote location, but in the densely-populated British Isles the only such locations were in the north and west of Scotland. By April 1947, Hinton had convinced Portal of the advantages of a gas-cooled system. Helium was at first the preferred choice as a coolant gas, but the main source of it was the United States, and under the McMahon Act, the United States would not supply it for nuclear weapons production, so, in the end, air cooling was chosen. With the need for a remote site obviated, it was decided to build the facility on the coast of Cumberland at a former Royal Ordnance Factory, ROF Drigg. This was soon switched to a more suitable site at the nearby former

ROF Sellafield Sellafield is a large multi-function nuclear site close to Seascale on the coast of Cumbria, England. As of August 2022, primary activities are nuclear waste processing and storage and nuclear decommissioning. Former activities included nucl ...

. To avoid any confusion with Springfields, the name was changed to Windscale. Construction began in September 1947. The danger of the

Wigner Effect The Wigner effect (named for its discoverer, Eugene Wigner), also known as the discomposition effect or Wigner's disease, is the displacement of atoms in a solid caused by neutron radiation. Any solid can display the Wigner effect. The effect is ...

was not overlooked. Walter Zinn visited Britain in 1948 and provided crucial information. New calculations based on this meant that the layout of the graphite blocks, which were already being machined, had to be changed. The two Windscale reactors became operational in October 1950 and June 1951. Due to faulty calculations at the design stage, the reactors did not produce the expected output. As a result, extraordinary measures had to be taken to provide Penney with a first shipment of plutonium in June 1952, and sufficient quantity for a core by the 1 August 1952 deadline. Improvements in the bomb design ultimately meant that he could get by with 15 per cent less plutonium. Starting in 1953, the Windscale reactors were able to use slightly enriched uranium as a fuel. They were shut down after the

Windscale fire The Windscale fire of 10 October 1957 was the worst nuclear accident in the United Kingdom's history, and one of the worst in the world, ranked in severity at level 5 out of a possible 7 on the International Nuclear Event Scale. The fire was in ...

in October 1957.

Plutonium processing facility

Cartridges of uranium were irradiated in the Windscale reactors to produce plutonium. The cartridges were pushed through the reactor, and exited on the other side, where they fell into submerged steel skips which were pulled into a deep cooling pond. After being irradiated, each cartridge contained as many as 180

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

of 35 different

chemical element A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...

s. Less than half of one per cent of the feed would have been converted to plutonium, but about 5 per cent was now radioactive fission products, the remainder being slightly depleted uranium. After being stored underwater for 150 days, the short-lived isotopes had decayed, leaving significant quantities of about 20 radioactive isotopes. Using remote handling, the cartridges were placed in lead-lined "coffins" and transported to the chemical separation plant. At Hanford, the Americans had used a bismuth phosphate process to separate the plutonium from the uranium. This was wasteful; the plutonium was retrieved, but the uranium was left in a state from which it could not easily be recovered. A team at the Montreal Laboratory investigated this problem, and had devised a new process similar to that used with uranium. They had tried out the process, which they believed could be employed on an industrial scale, to extract 20 mg of plutonium from a spent Hanford fuel rod. The cartridges were dissolved in nitric acid and dibutyl carbitol was used to remove the plutonium. After 1946, the only source of plutonium was from the NRX reactor in Canada, and irradiated rods from there did not arrive in Britain until mid-1948. Nor would Harwell have been able to handle them if they had; a "hot" radioactive laboratory was not built until 1949, although a small hot laboratory was pressed into service in 1948. A pilot plant was established at the

Chalk River Laboratories Chalk River Laboratories (french: Laboratoires de Chalk River; also known as CRL, Chalk River Labs and formerly Chalk River Nuclear Laboratories, CRNL) is a Canadian nuclear research facility in Deep River, about north-west of Ottawa. CRL is ...

, which ran until 1950. Despite concerns over whether the process would work, numerous minor changes, and construction problems related to the steel used, the plant was completed on schedule in April 1951. The first active material was fed into the plant on 25 February 1952. The plant performed well for twelve years, exceeding its designed production targets, and was only decommissioned when a larger facility was required. The first plutonium billet was cast on 31 March 1952, but it was impure, and could not be used in a bomb. Further work at Harwell and Windscale was required to perfect the process.

Gaseous diffusion plant

The gaseous diffusion plant was the most complicated of all from an engineering point of view.

Uranium hexafluoride Uranium hexafluoride (), (sometimes called "hex") is an inorganic compound with the formula UF6. Uranium hexafluoride is a volatile white solid that reacts with water, releasing corrosive hydrofluoric acid. The compound reacts mildly with alumin ...

gas was pumped into a cascade, becoming richer in uranium-235 at each stage as it passed through a series of membranes. Procuring the nickel powder used by the Manhattan Project was not a problem, as it came from a British firm. Once again, a Royal Ordnance Factory was chosen as the site, in this case ROF Capenhurst at Capenhurst, near Chester, which had the advantage of being only from Risley. One decision was that instead of producing uranium hexafluoride using elemental fluorine, which was difficult and hazardous to transport, it was produced at Springfields from

chlorine trifluoride Chlorine trifluoride is an interhalogen compound with the formula ClF3. This colorless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temp ...

. This process was untried and did not work properly, and when production commenced in February 1952, the hexafluoride plant did not perform adequately. It had to be redesigned at a cost of £250,000. The gaseous diffusion plant at Capenhurst, which cost £14 million, started production in 1953, but only produced low-enriched uranium, and did not produce

until 1954. By 1957 it was capable of producing 125 kg of highly enriched uranium per annum. British designs at this time used large amounts of enriched uranium; 87 kg for

Green Bamboo ''Yellow Sun'' was the first British operational high-yield strategic nuclear weapon warhead. The name refers only to the outer casing; the warhead (or physics package) was known as "Green Grass" in Yellow Sun Mk.1 and "Red Snow" in Yellow Sun Mk ...

, 117 kg for

Orange Herald Orange Herald was a British nuclear weapon, tested on 31 May 1957. At the time it was reported as an H-bomb, although in fact it was a large boosted fission weapon and remains to date, the largest fission device ever detonated. Technical Oran ...

. At the end of 1961, having produced between 3.8 and 4.9 tonnes of highly enriched uranium, it was switched over to low-enriched uranium production for civil nuclear power.

Bomb design

Key staff recruited to work at Fort Halstead included John Challens, who commenced on 1 January 1948. By mid-1948, it became clear that Penney's initial estimate that he would require 220 staff was wide of the mark, and that he would need nearly 500. This meant not only taking personnel from other projects, but scrapping some entirely. In October 1948, Penney submitted a request for developing a new, separate site for HER on grounds of safety, security and economy. This was approved, but it took another six months to locate a suitable site. An airbase,

RAF South Cerney Royal Air Force South Cerney or more simply RAF South Cerney is a former Royal Air Force station located in South Cerney near Cirencester in Gloucestershire, England. It was built during the 1930s to conduct flying training. The airfield was tu ...

Gloucestershire Gloucestershire ( abbreviated Glos) is a county in South West England. The county comprises part of the Cotswold Hills, part of the flat fertile valley of the River Severn and the entire Forest of Dean. The county town is the city of Gl ...

was chosen, but the RAF refused to relinquish the site. A former airbase, RAF Aldermaston, was then selected. At the same time, it was decided to separate HER from the Armaments Research Establishment (ARE). This resulted in a painful bureaucratic battle over personnel like Challens, whose expertise was wanted for research on both nuclear weapons and guided missiles. In the end, HER kept 25 of the 30 key personnel that ARE wanted, including Challens. The site was taken over on 1 April 1950. Penney became Chief Superintendent High Explosive Research (CSHER). The first stage of work at Aldermaston was completed in December 1951, but the plutonium processing building was only handed over in April 1952, the month that the first plutonium was due to arrive from Windscale. At the peak of construction in 1953, over 4,000 personnel were working on the site. Implosion bomb animated

The choice of plutonium for the fissile component of the bomb meant that Penney's HER team at Fort Halstead had to design an

implosion-type nuclear weapon Nuclear weapon designs are physical, chemical, and engineering arrangements that cause the physics package of a nuclear weapon to detonate. There are three existing basic design types: * pure fission weapons, the simplest and least technically ...

. The Los Alamos Laboratory had solved the problem of doing this with

explosive lens An explosive lens—as used, for example, in nuclear weapons—is a highly specialized shaped charge. In general, it is a device composed of several explosive charges. These charges are arranged and formed with the intent to control the shape ...

es. The involvement of several British scientists gave HER a solid base of experience to work from. The British design would hew to that of the American

Fat Man "Fat Man" (also known as Mark III) is the codename for the type of nuclear bomb the United States detonated over the Japanese city of Nagasaki on 9 August 1945. It was the second of the only two nuclear weapons ever used in warfare, the fir ...

as closely as possible. An important change would be the substitution of

RDX RDX (abbreviation of "Research Department eXplosive") or hexogen, among other names, is an organic compound with the formula (O2N2CH2)3. It is a white solid without smell or taste, widely used as an explosive. Chemically, it is classified as a ...

, an ARD product, for

Composition B Composition B, colloquially Comp B, is an explosive consisting of castable mixtures of RDX and TNT. It is used as the main explosive filling in artillery projectiles, rockets, land mines, hand grenades and various other munitions. It was also ...

as the fast explosive component of the lenses;

Baratol Baratol is an explosive made of a mixture of TNT and barium nitrate, with a small quantity (about 1%) of paraffin wax used as a phlegmatizing agent. TNT typically makes up 25% to 33% of the mixture. Because of the high density of barium nitrate, ...

would still provide the slow component. This was handled by the explosives experts at Woolwich, who devised the machining processes and produced prototypes of the lenses and moulds. Production was then handled by two Royal Ordnance Factories. The first lenses were delivered in 1952, and there were enough for two sets for the

assemblies. Woolwich provided the supercharge, the spherical shell of explosive that encases the tamper. Test firings of explosive lenses were conducted at

Foulness Foulness Island () is a closed island on the east coast of Essex in England, which is separated from the mainland by narrow creeks. In the 2001 census, the usually resident population of the civil parish was 212, living in the settlements of Ch ...

by a team under the direction of Roy Pilgrim. To achieve near-simultaneous detonations of the lenses, the Americans had developed the

exploding-bridgewire detonator The exploding-bridgewire detonator (EBW, also known as exploding wire detonator) is a type of detonator used to initiate the detonation reaction in explosive materials, similar to a blasting cap because it is fired using an electric current. EBW ...

; this had to be duplicated. Ernest Mott and Cecil Bean developed them, while Challens devised the firing circuits. Work on the plutonium core had to wait until Windscale delivered sufficient product, which was not until late 1951. The uranium tamper proved more of a challenge for the metallurgists than anticipated, due to a shortage of machine tools and moulds, and difficulty with the

vacuum furnace A vacuum furnace is a type of furnace in which the product in the furnace is surrounded by a vacuum during processing. The absence of air or other gases prevents oxidation, heat loss from the product through convection, and removes a source of co ...

. The first spheres were cast in December 1951, and while they were spherical to within , there were some casting defects, and it was feared they would hinder the implosion process. The defects were repaired, and two castings were prepared for Operation Hurricane. Work on plutonium chemistry and metallurgy was carried out at Harwell, as the hot laboratory at Aldermaston was not completed until May 1952. The first plutonium billet was cast there from plutonium nitrate from the Chalk River Laboratories in 1951. The metallurgists chose to alloy the plutonium with gallium to stabilise it in the malleable δ phase allotrope. Not until the first billet arrived from Harwell in 1951 were they able to confirm that this was practical. The first plutonium at Aldermaston was cast in an

argon Argon is a chemical element with the symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third-most abundant gas in Earth's atmosphere, at 0.934% (9340 ppmv). It is more than twice as ...

atmosphere in a cerium sulphide crucible. The other radioactive element in use was

polonium Polonium is a chemical element with the symbol Po and atomic number 84. Polonium is a chalcogen. A rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character ...

, which was used in the

initiator An initiator can refer to: * A person who instigates something. * Modulated neutron initiator, a neutron source used in some nuclear weapons ** Initiator, an Explosive booster ** Initiator, the first Nuclear chain reaction * Pyrotechnic initiato ...

. It was one of the parts of the Manhattan Project that the British mission had not been involved in, and little was known about its chemistry and properties, except that it had a

half-life Half-life (symbol ) is the time required for a quantity (of substance) to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable at ...

of 138 days. A disturbing discovery was that motes of polonium could propel themselves through the air using their own

alpha particle Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be pr ...

emissions. Safety procedures had to be tightened. It was produced at Windscale by irradiation of

bismuth Bismuth is a chemical element with the symbol Bi and atomic number 83. It is a post-transition metal and one of the pnictogens, with chemical properties resembling its lighter group 15 siblings arsenic and antimony. Elemental bismuth occurs ...

. A special plant was built there to extract it, but it was not operational until June 1952. The final product was just of polonium, less than 1 mg. It was only just available on time for Operation Hurricane. A small RAF team that eventually numbered ten men was assigned to liaise with HER, under the command of

Wing Commander Wing commander (Wg Cdr in the RAF, the IAF, and the PAF, WGCDR in the RNZAF and RAAF, formerly sometimes W/C in all services) is a senior commissioned rank in the British Royal Air Force and air forces of many countries which have historical ...

John Rowlands. He was answerable to a committee at the Air Ministry, codenamed "Herod". They considered how atomic bombing missions would be flown, and prepared training courses and manuals on how the production weapon, codenamed Blue Danube, would be stored, handled and maintained. The ballistic casing of the bomb was designed at Farnborough. Rowlands was responsible for an important design change. For safety reasons, he wanted the core inserted like a plug while the bomber was in flight. Fuchs performed calculations of the nuclear physics involved at Harwell in 1948, and produced an alternative design that, while untried, could be used. The new British design incorporated a

levitated pit The pit, named after the hard core found in fruits such as peaches and apricots, is the core of an implosion nuclear weapon – the fissile material and any neutron reflector or tamper bonded to it. Some weapons tested during the 1950s used p ...

, in which there was an air gap between the uranium tamper and the plutonium core. This gave the explosion time to build up momentum, similar in principle to a hammer hitting a nail.

Testing

Implicit in the decision to develop atomic bombs was the need to test them. The preferred site was the American

Pacific Proving Grounds The Pacific Proving Grounds was the name given by the United States government to a number of sites in the Marshall Islands and a few other sites in the Pacific Ocean at which it conducted nuclear testing between 1946 and 1962. The U.S. tested a ...

. As a fallback, sites in Canada and Australia were considered. In September 1950, the

suggested that the

in Australia might be suitable, so Attlee sent a request to the Prime Minister of Australia, Robert Menzies, for permission to send a survey party to have a look at the islands. Menzies agreed, and in November 1950, a three-man party headed by Air Vice Marshal E. D. Davis was sent out to the islands. The Australian government formally agreed to the islands being used in May 1951, and in December 1951 the new British government under Winston Churchill confirmed the choice of test site. On 26 February 1952 Churchill announced in the House of Commons that the first British atomic bomb test would occur in Australia before the end of the year. A small fleet was assembled for Operation Hurricane that included the aircraft carrier , which served as the flagship, and the LSTs ''Narvik'', ''Zeebrugge'' and ''Tracker'', under the command of Rear Admiral A. D. Torlesse. Leonard Tyte from Aldermaston was appointed the technical director. The bomb assemblies for Operation Hurricane were assembled at Foulness, and then taken to the frigate on 5 June 1952 for transport to Australia. It took ''Campania'' and ''Plym'' eight weeks to make the voyage, as they sailed around the Cape of Good Hope to avoid traversing the Suez Canal, as there was unrest in Egypt at the time. The Monte Bello Islands were reached on 8 August. They were joined by eleven

Royal Australian Navy The Royal Australian Navy (RAN) is the principal naval force of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (CN) Vice Admiral Mark Hammond AM, RAN. CN is also jointly responsible to the Minister of ...

ships, including the aircraft carrier . The plutonium core went by air, flying from

RAF Lyneham Royal Air Force Lyneham otherwise known as RAF Lyneham was a Royal Air Force station located northeast of Chippenham, Wiltshire, and southwest of Swindon, Wiltshire, England. The station was the home of all the Lockheed C-130 Hercules transpor ...

to Singapore in a

Handley Page Hastings The Handley Page HP.67 Hastings is a retired British troop-carrier and freight transport aircraft designed and manufactured by aviation company Handley Page for the Royal Air Force (RAF). Upon its introduction to service during September 1948, ...

aircraft via Cyprus,

Sharjah Sharjah (; ar, ٱلشَّارقَة ', Gulf Arabic: ''aš-Šārja'') is the third-most populous city in the United Arab Emirates, after Dubai and Abu Dhabi, forming part of the Dubai-Sharjah-Ajman metropolitan area. Sharjah is the capital ...

and Ceylon. From Singapore they made the final leg of their journey in a

Short Sunderland The Short S.25 Sunderland is a British flying boat patrol bomber, developed and constructed by Short Brothers for the Royal Air Force (RAF). The aircraft took its service name from the town (latterly, city) and port of Sunderland in North Ea ...

flying boat. Penney arrived by air on 22 September. The bomb was successfully detonated on board ''Plym'' at 09:29:24 on 3 October 1952 local time (23:59:24 on 2 October 1952 UTC). The explosion occurred below the water line, and left a saucer-shaped crater on the seabed deep and across. The yield was estimated at .

Delivery systems

A July 1945 Tizard Committee report foresaw the advent of long-range rockets and pilotless aircraft, but did not envision them as likely within ten years, and therefore urged the development of long-range jet

bomber A bomber is a military combat aircraft designed to attack ground and naval targets by dropping air-to-ground weaponry (such as bombs), launching torpedoes, or deploying air-launched cruise missiles. The first use of bombs dropped from an air ...

s. In 1946, the RAF's front line bomber was the Avro Lincoln, a development of the wartime Avro Lancaster. It did not have the range to reach targets in the Soviet Union, nor could it deal with jet fighter interceptors.

Operational Requirement An Operational Requirement, commonly abbreviated OR, was a United Kingdom (UK) Air Ministry document setting out the required characteristics for a future (i.e., as-yet unbuilt) military aircraft or weapon system. The numbered OR would describe ...

(OR229) called for a high-altitude jet bomber with a range of carrying an atomic bomb. The 9 August 1946 requirement for an atomic bomb (OR1001) specified that it be not more than in length or in diameter, and weigh no more than . Vickers Valiant BK

OR229 was approved by the Operational Requirements Committee on 17 December 1946, and the Ministry of Supply sent out letters inviting tenders on 8 January 1947. Three bombers resulted from OR229: the Vickers Valiant,

Avro Vulcan The Avro Vulcan (later Hawker Siddeley Vulcan from July 1963) is a jet-powered, tailless, delta-wing, high-altitude, strategic bomber, which was operated by the Royal Air Force (RAF) from 1956 until 1984. Aircraft manufacturer A.V. Roe an ...

and

Handley Page Victor The Handley Page Victor is a British jet-powered strategic bomber developed and produced by Handley Page during the Cold War. It was the third and final '' V bomber'' to be operated by the Royal Air Force (RAF), the other two being the Avr ...

, known as the V bombers. The high priority accorded to the atomic bomb programme was not shared by the V bomber programme. Vickers was given the first production order for 25 Valiants on 9 February 1951, and they were delivered on 8 February 1955. The Vulcan and Victor followed, entering service in 1956 and 1957 respectively. Thus, when the first Blue Danube atomic bombs were delivered to the

Armaments School at

RAF Wittering Royal Air Force Wittering or more simply RAF Wittering is a Royal Air Force station within the unitary authority area of Peterborough, Cambridgeshire and the unitary authority area of North Northamptonshire. Although Stamford in Lincolnshire i ...

on 7 and 11 November 1953, the RAF had no bombers capable of carrying them. Penney noted that "the RAF has handled aircraft for a long time and can fly Valiants as soon as they come off the production line. But the Royal Air Force has not yet handled atomic weapons, therefore, we must get some bombs to the RAF at the earliest possible moment, so that the handling and servicing can be practised and fully worked out." For the time being, the United Kingdom remained dependent on the American

nuclear umbrella The "nuclear umbrella" is a guarantee by a nuclear weapons state to defend a non-nuclear allied state. The context is usually the security alliances of the United States with Japan, South Korea, and the North Atlantic Treaty Organization (much ...

. On 5 November 1953, the Air and Naval Staffs therefore issued an Operational Requirement (OR1127) for a smaller, lighter atomic bomb capable of being carried by their

English Electric Canberra The English Electric Canberra is a British first-generation, jet-powered medium bomber. It was developed by English Electric during the mid- to late 1940s in response to a 1944 Air Ministry requirement for a successor to the wartime de Havil ...

Gloster Javelin The Gloster Javelin is a twin-engined T-tailed delta-wing subsonic night and all-weather interceptor aircraft that served with Britain's Royal Air Force from the mid-1950s until the late 1960s. The last aircraft design to bear the Gloster name ...

and

Supermarine Scimitar The Supermarine Scimitar was a single-seat naval strike aircraft designed and produced by the British aircraft manufacturer Supermarine. Operated exclusively by the Royal Navy's Fleet Air Arm, it was the final aircraft to be entirely designed a ...

aircraft. Aldermaston commenced work on the new bomb, codenamed

Red Beard is a 1965 Japanese ''jidaigeki'' film co-written, edited, and directed by Akira Kurosawa, in his last collaboration with actor Toshiro Mifune. Based on Shūgorō Yamamoto's 1959 short story collection, '' Akahige Shinryōtan'', the film takes p ...

, in 1954. It had a composite uranium-plutonium core, and used air lenses to reduce its dimensions while still having a yield of 10 kilotons. Indeed, later boosted versions had yields of up to 100 kilotons. Red Beard weighed , about a fifth of Blue Danube, was long and in diameter. It was tested in the Operation Buffalo

British nuclear tests at Maralinga Between 1956 and 1963, the United Kingdom conducted seven nuclear tests at the Maralinga site in South Australia, part of the Woomera Prohibited Area about north west of Adelaide. Two major test series were conducted: Operation Buffalo in 195 ...

in September and October 1956, but various problems encountered meant that deliveries of production versions to the RAF and Royal Navy did not occur until 1960.

Outcome

In 1951, Penney wrote that "the discriminative test for a first-class power is whether it has made an atomic bomb and we have either got to pass the test or suffer a serious loss of prestige both inside this country and internationally." There was fear of being left behind, and hope that the United States would be sufficiently impressed to resume the Special Relationship. The successful test of an atomic bomb represented an extraordinary technological achievement. Britain became the world's third nuclear power. High Explosive Research achieved its objective with remarkable economy and efficiency, but the price was still high. Between 1946 and 1953, Risley spent £72 million, Harwell almost £27 million and the weapons establishment over £9.5 million. By comparison, British defence expenditure in 1948 was £600 million. HER accounted for 11 per cent of the Ministry of Supply's expenditure between 1946 and 1953. It had bi-partisan and popular support. Given Britain's dire financial position, thought turned to replacing conventional forces with atomic bombs. While certainly expensive, they could deliver extraordinary destructive power at relatively low cost. The concept of

deterrence Deterrence may refer to: * Deterrence theory, a theory of war, especially regarding nuclear weapons * Deterrence (penology), a theory of justice * Deterrence (psychology) Deterrence in relation to criminal offending is the idea or theory that t ...

began to evolve, based on experiences dating back to the

Great War World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

. There were also technological spin-offs. The possession of nuclear reactors, the means to produce nuclear fuels and a repository of scientific knowledge led to the creation of a vast

nuclear power Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced ...

industry. Yet all the while Britain strived for independence, at the same time it sought interdependence in the form of a renewal of the Special Relationship with the United States. This was desired more than ever, as other countries recovered from the war and once again began to challenge Britain's status. As successful as it was, High Explosive Research fell short on both counts. The technology demonstrated at Monte Bello in October 1952 was already seven years old. The following month the United States tested

Ivy Mike Ivy Mike was the codename given to the first full-scale test of a thermonuclear device, in which part of the explosive yield comes from nuclear fusion. Ivy Mike was detonated on November 1, 1952, by the United States on the island of Elugelab ...

, a thermonuclear device. The British government would now have to decide whether to initiate its own hydrogen bomb programme. Penney, for one, feared that this would likely prove to be beyond the financial resources of Britain's war-ravaged economy. The successful

British hydrogen bomb programme 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 ...

, and a favourable international relations climate caused by the Sputnik crisis, led to amendment of the United States Atomic Energy Act in 1958, and a resumption of the nuclear Special Relationship between America and Britain under the

1958 US–UK Mutual Defence Agreement Events January * January 1 – The European Economic Community (EEC) comes into being. * January 3 – The West Indies Federation is formed. * January 4 ** Edmund Hillary's Commonwealth Trans-Antarctic Expedition completes the third ...

Notes

References

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * {{Featured article Code names Former nuclear research institutes Nuclear history of the United Kingdom