Tube Alloys

Tube Alloys was a codename of the clandestine research and development programme, authorised by the Government of the United Kingdom with participation from Canada, aiming to develop atomic weapons for Great Britain's nuclear programme during the Second World War. Starting with the Western Allies's nuclear bomb project in 1942, the British efforts were kept in extremely high-level secrecy such that they had to be referred to by code even within the highest circles of government. At the end of the Second World War, Tube Alloys came to refer specifically to the element plutonium, whose very existence was secret until its use in the atomic bombing of Nagasaki.

The Tube Alloys programme in Britain and Canada, effectively the first nuclear weapons project of its type, was eventually subsumed into the US-led Manhattan Project. Both programmes had some elements of earlier research accomplished in France and Germany. Despite reaching the understanding with the United States, the details of such efforts weren't completely provided to the United Kingdom, although ironically the Soviet Union gained valuable details, scientific data and research documents through subterfuge critical for the development of nuclear weapons. This prompted the United Kingdom to (re)launch its own directorate to match the achievements of the Soviets and Americans. Production facilities were established under the auspices of the British Army and Royal Air Force and British scientists were re-called from the United States to continue their work under the auspices of an independent British programme. Finally in 1952, Britain performed a test under codename Hurricane, a decade after conducting research on the field. In 1958, after British demonstration of a two-stage thermonuclear (fission-fusion) bomb, the United Kingdom and the United States signed a defence understanding agreement that resulted in the United Kingdom electing to resume its nuclear weapons co-operation with the United States.

The Paris Group
Otto Hahn in Germany and Lise Meitner, exiled in Sweden, reported nuclear fission in uranium in 1938. This was followed up by a group of scientists at the Collège de France in Paris: Frédéric Joliot-Curie, Hans von Halban, Lew Kowarski, and Francis Perrin. In February 1939, the Paris Group showed that when fission occurs in a uranium nucleus, two or three extra neutrons are also given off. This important observation suggested that a self-sustaining chain reaction might be possible. It was immediately apparent to many scientists that, in theory, an extremely powerful explosive could be created, an atomic bomb, but many scientists thought a practical bomb was an impossibility.

Francis Perrin of the Paris Group defined a critical mass of uranium to be the smallest amount that could sustain a chain reaction. However, it was found that natural uranium cannot sustain a chain reaction without a moderator to slow down the fast-moving neutrons given off by the fission. Early in 1940, the Paris Group decided on theoretical grounds that heavy water would be an ideal moderator. They asked the French Minister of Armaments to obtain as much heavy water as possible from the only source, the large Norsk Hydro hydroelectric station at Vemork in Norway. The French then discovered that Germany had already offered to purchase the entire stock of Norwegian heavy water, indicating that Germany might also be researching an atomic bomb. The French told the Norwegian government of the possible military significance of heavy water. Norway then gave the entire stock to a French Secret Service agent, who secretly brought it to France, just before Germany invaded Norway in April 1940. On 19 June 1940 it was shipped to England by Charles "Jack" Howard, Earl of Suffolk and Major Ardale Vautier Golding, on the steamer SS Broompark,. The heavy water was subsequently secretly stored in the library at Windsor Castle When Germany invaded France in May 1940, the Paris Group moved to Cambridge and brought the heavy water inventory of 188 litres. Joliot-Curie remained in France and became an active worker in the French Resistance movement.

MAUD Committee
In February 1940, Otto Frisch and Rudolf Peierls, while researching at Birmingham University, considered the possibility of fast fission in uranium-235. The team approximated the critical mass of pure U-235, which was only a "pound or two", and asserted that much of this mass is sufficient enough to react and blown away by the explosion. The team directed the report to their professor Marcus Oliphant who informed Henry Tizard who was the Chairman of the Committee on the Scientific Survey of Air Defence of British Army. The March 1940 Frisch–Peierls memorandum resulted in Tizard setting up of the British MAUD Committee to investigate the feasibility of an atomic bomb. The memo prompted the MAUD Report which in turn led to the Tube Alloys project. The MAUD Committee consisted a chairman George Paget Thomson and had Marcus Oliphant, Patrick Blackett, James Chadwick, Philip Moon and John Cockcroft as its committee's members.

Uranium enrichment
The British put much effort into exploring the possibility of successfully enriching the minimum required quantity of uranium. Dr. Rudolf Peierls, a German scientist who was working in the United Kingdom when Adolf Hitler came to power in Germany, and had then elected to stay, was working at the University of Birmingham. Peierls attempted to derive the critical mass of a block of pure uranium. In a paper entitled "Critical Conditions on Neutron Multiplication" delivered to the Cambridge Philosophical Society on 14 June 1939, he calculated that it was of the order of tons, too large to make into a practical bomb. However, with his friend Otto Frisch, a fellow German scientist living in exile in England, Peierls then began to examine the neutron cross section of uranium-235, the rare lighter isotope that makes up only 0.7% of natural uranium, the rest being uranium-238. Their calculations indicated that it was within an order of magnitude of 10 kg, small enough to be carried by a bomber of the day.

Tizard Mission
The heavy water team from France was invited to continue its slow neutron research at Cambridge University; but the project was given a low priority since it was not expected to produce a bomb.

A delegation (the Tizard Mission) was sent in September 1940 to North America to exchange technology in all fields, such as radar, jet engines and nuclear research. They also explored the possibility of relocating the British military research facilities in North America, out of reach of the German bombers.

When the Tizard Mission returned they reported on the slow neutron researches being conducted in Cambridge (by the Paris Group), at Columbia University by Enrico Fermi and in Canada by George Laurence. They concluded that they were irrelevant to the war effort.

Isotopic separation
The biggest problem faced by the MAUD Committee was to find a way to separate the 0.7% of uranium-235 from the 99.3% of uranium-238. This is difficult because the two types of uranium are chemically identical. However, Franz Simon had been commissioned by MAUD to investigate methods. Simon reported in December 1940 that gaseous diffusion was feasible, calculating the size and cost of the industrial plant needed. The MAUD Committee realised that an atomic bomb was "not just feasible; it was inevitable".

The chemical problems of producing gaseous compounds of uranium and pure uranium metal were studied at the University of Birmingham and Imperial Chemical Industries (ICI). Very early experiments were carried out by Michael Clapham who at the time was working on print technology at the Kynoch Works in Aston in Birmingham, according to an interview he gave to a BBC documentary broadcast in 2000. Dr Philip Baxter at ICI made the first small batch of gaseous uranium hexafluoride for Professor James Chadwick in 1940. ICI received a formal contract later in 1940 to make 3 kg of this vital material for the future work. The prototype gaseous diffusion equipment itself was manufactured by Metropolitan-Vickers (MetroVick) at Trafford Park, Manchester, at a cost of £150,000 for four units. Some of the Tube Alloys secret development work was carried out by Britain's Imperial Chemical Industries Ltd (ICI) based at Billingham, Northeast England. Evidence in a TV programme transmitted by Tyne Tees Television (Northern Life) established a connection between work carried out at ICI and nuclear material.

Plutonium
The breakthrough with plutonium was at the Cavendish Laboratory by Egon Bretscher and Norman Feather. They realised that a slow neutron reactor fuelled with uranium would theoretically produce substantial amounts of plutonium-239 as a by-product. This is because U-238 absorbs slow neutrons and forms a new isotope U-239. The new isotope's nucleus rapidly emits an electron through beta decay producing a new element with a mass of 239 and an atomic number of 93. This element's nucleus then also emits an electron and becomes a new element of mass 239 but with an atomic number 94 and a much greater half-life. Bretscher and Feather showed theoretically feasible grounds that element 94 would be readily 'fissionable' by both slow and fast neutrons, and had the added advantage of being chemically different from uranium, and could easily be separated from it.

This new development was also confirmed in independent work by Edwin M. McMillan and Philip Abelson at Berkeley Radiation Laboratory also in 1940. Nicholas Kemmer of the Cambridge team proposed the names neptunium for the new element 93 and plutonium for 94 by analogy with the outer planets Neptune and Pluto beyond Uranus (uranium being element 92). The Americans fortuitously suggested the same names. The production and identification of the first sample of plutonium in 1941 is generally credited to Glenn Seaborg, using a cyclotron rather than a reactor.

Oliphant's visit to the United States
When there was no reaction from America to the reports of the MAUD Committee, Mark Oliphant crossed the Atlantic in an unheated bomber in August 1941. He found that Lyman Briggs had not circulated the reports to the Uranium Committee, but had kept them in a safe. Oliphant then contacted Ernest Lawrence, James Conant, Enrico Fermi and Arthur Compton and managed to increase the urgency of the American research programmes. The MAUD Reports finally made a big impression. Overnight the Americans changed their minds about the feasibility of an atomic bomb and suggested a cooperative effort with Britain. Harold C. Urey and George Braxton Pegram were sent to the UK in November 1941, to confer but Britain did not take up the offer of collaboration. The offer lapsed without any action being taken.

Tube Alloys and the United States
The American effort increased rapidly and soon outstripped the British as the American authorities were reluctant to share details with their British counterparts. However, separate research continued in each country with some exchange of information. Several of the key British scientists visited the United States early in 1942 and were given full access to all of the information available. They were astounded at the momentum that the American atomic bomb project had then assumed. The British and American exchange of information and efforts continued but the nations did not combine their efforts, leading their programmes separately. Furthermore, in 1941 the British Government rebuffed and vetoed attempts and proposals by U.S. Science Adviser Vannevar Bush and highly regarded U.S. government official James Bryant Conant to strengthen cooperation between Great Britain and America. This had a disastrous impact on British efforts as they lacked the manpower, facilities, equipment and materials needed, therefore Tube Alloys fell behind in the race with the Manhattan Project. On 30 July 1942, the British civil servant Sir John Anderson advised Prime Minister Winston Churchill, quoting that: "Sir... We must face the fact that ... [our] pioneering 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" By the time Great Britain realised it, the position had worsened, Bush decided that outside help for the Manhattan Project was no longer needed while the U.S. government was increasingly convinced of the fact; that prevented Great Britain from being able to build a postwar atomic weapon. The Military Policy Committee (MPC) supported Bush's arguments and restricted access to the classified information which Britain could utilize to develop its atomic weapons program, even if it slowed down the American efforts.

In June 1942, the U.S. Army took over the process of development, engineering design, procurement of materials, and site selection for pilot plants and facilities for the research. Lieutenant-General Leslie Groves of the Corps of Engineers tightened the security of the American atomic bomb programme, that dried up the information flow to Britain.

The Americans stopped sharing any information on heavy water production, the manufacture of uranium hexafluoride, the method of electromagnetic separation, the physical or chemical properties of plutonium, the details of bomb design, or the facts about fast neutron reactions. This was a major disappointment which hindered the British and the Canadians, who were collaborating on heavy water production and several other aspects of the research programme. By 1943, Britain stopped sending its scientists to the United States which slowed down the pace of work that was being done there. The British boycott had a deep impact on the American project which had relied on efforts led by British scientists. On March 1943, Conant approached the bomb policy committee which decided that Britain's help would benefit some areas of the project. James Chadwick, William Penney and one or two other British scientists were important enough that the bomb design team at Los Alamos Laboratory needed them, despite the risk of revealing weapon design secrets.

Montreal Laboratory
The slow neutron research at the Cavendish Laboratory of Cambridge University which the British had thought was not relevant to bomb-making, suddenly acquired military significance, because it provided the route to plutonium. Understanding the difficulties faced by the British, the British government started employing a large number of capable scientists from their colonies and from allied countries, mostly recommended by Mark Oliphant. The British Government wanted the Cambridge team to be relocated to Chicago, where the American research was being done, but the Americans had become very security conscious. Only one of the six senior scientists in the Cambridge group, which had originated in Paris, was British. They were therefore sent to Montreal, Canada.

The first eight staff arrived in Montreal at the end of 1942, and occupied a house belonging to McGill University. Three months later they moved into a 200 square metre area in a new building at the University of Montreal. The laboratory grew quickly to over 300 staff; about half were Canadians recruited by George Laurence. A subgroup of theoreticians was recruited and headed by a Czechoslovak physicist, George Placzek. Placzek proved to be a very capable group leader, and was generally regarded as the only member of the staff with the stature of the highest scientific rank and with close personal contacts with many key physicists involved in the Manhattan project. The Director of the laboratory was Hans von Halban, but he proved to be an unfortunate choice as he was a poor administrator, and did not work well with the National Research Council of Canada. The Americans saw him as a security risk, and objected to the French atomic patents claimed by the Paris Group (in association with ICI).

The Montreal team in Canada depended on the Americans for supplies of heavy water from the US heavy water plant in Trail, British Columbia (which was under American contract), as well as technical information about plutonium. The Americans said that they would give heavy water to the Montreal group only if it agreed to direct its research along the limited lines suggested by du Pont. Despite doing much good work, by June 1943 work at the Montreal Lab had come to a complete standstill. Morale was low and the Canadian Government proposed cancelling the project. The Quebec Agreement in 1943 had led to more co-operation with America, though most of the British Mission scientists were based at Berkeley or Los Alamos.

In April 1944 a Combined Policy Committee meeting in Washington agreed that Canada would build a heavy water reactor. Scientists who were not British subjects would leave, and John Cockcroft would become the new Director of the Montreal Laboratory. The Americans fully supported the project with information and visits. They also supplied material e.g. uranium and heavy water. The Chalk River Laboratories opened in 1944, and in 1946 the Montreal Laboratory was closed. The project developed the ZEEP reactor.

The Quebec Agreement
Winston Churchill then sought information about building Britain's own diffusion plant, a heavy water plant and an atomic reactor in Britain, despite its immense cost. However, in July 1943, in London, American officials cleared up some major misunderstandings about British motives, and after many months of negotiations the Quebec Agreement was finally signed by Churchill and US President Franklin D. Roosevelt on 19 August 1943. The British then handed over all of their material to the Americans and in return received the copies of all the American progress reports to the President. The British effort was then subsumed into the Manhattan Project until after the war.

In a section of the Quebec Agreement formally entitled "Articles of Agreement governing collaboration between the authorities of the USA and UK in the matter of Tube Alloys", Britain and the USA agreed to share resources "to bring the Tube Alloys [i.e. the Atomic Bomb] project to fruition at the earliest moment."

The leaders agreed that
 * "we will never use this agency against each other,
 * "we will not use it against third parties without each other's consent, and
 * "we will not either of us communicate any information about Tube Alloys to third parties except by mutual consent."

It was also agreed that any post-war advantages of an industrial or commercial nature would be decided at the discretion of the US President.

William Penney, one of the Tube Alloys scientists, was an expert in shock-waves. In June 1944 he went to America to work at Los Alamos as part of the British delegation to the Manhattan Project. His leadership qualities and his ability to work in harmony with others resulted in him being added to the core group of scientists who made all key decisions in the direction of the programme.

In 1945, US President Harry S. Truman had agreed to Churchill's request that British observers could witness the dropping of the bomb on Japan. But when Group Captain Leonard Cheshire and Professor William Penney went to Tinian, they were not allowed by Groves and/or LeMay to go on the Hiroshima flight, and only after protests went in the observation plane Big Stink on the Nagasaki flight. While Penney knew much of the theory of the Project, so did other members of Project Alberta who also flew over Japan.

The Smyth Report was issued by the US War Department on 12 August 1945, giving the story of the atomic bomb and including the technical details that could now be made public. It made few references to the British contribution to the bomb, and a White Paper, Statements Relating to the Atomic Bomb was hurriedly drafted by Michael Perrin. This account was issued just after Attlee had replaced Churchill as Prime Minister, and was the only official statement on the British contribution for fifteen years.

Soviet spies in the Tube Alloys project
The USSR got details of British initial research, from Klaus Fuchs and possibly also Austrian expatriate Engelbert Broda, and John Cairncross. Alan Nunn May was also recruited later in Canada. Lavrenty Beria’s report to Stalin of March 1942 included the MAUD report and other British documents.

Post-war
The Atomic Energy Research Establishment (AERE or the Harwell Laboratory) near Harwell, Oxfordshire was established by John Cockcroft in 1946 as the main centre for military and civilian atomic energy research and development in Britain. Former RAF bases were selected for AERE and AWRE as they were isolated, with large hangars. Hans von Halban was invited back to the UK by Frederick Lindemann (Lord Cherwell) to lead a team at the nearby Clarendon Laboratory in Oxford University, and worked there for eight years until 1955.

William Penney returned from the United States and appointed for the professorship (for Mathematics) at the Imperial College. Rather, Penney accepted the directorship position at the Armament Research Department (ARD) in 1946.

At the end of the war the British government had blindly trusted and thusly believed that America would share the (nuclear) technology, which the British saw as a joint discovery. However, the passing of the McMahon Act (Atomic Energy Act) by the President Harry Truman and his administration in August 1946, made it clear that Great Britain would no longer be allowed access to United States' atomic research. This partly resulted from the arrest for espionage of Alan Nunn May in 1946. On January 8, 1947, British PM Clement Attlee formed a secret "GEN.163 Cabinet committee", consisting of six civilian ministers of his government, charged with proceeding the efforts for Britain's nuclear programme.

Prime Minister Clement Attlee's government decided that Britain required the atomic bomb to maintain its position in world politics. In the words of Foreign Secretary Ernest Bevin - "That won't do at all .. we've got to have this .. I don't mind for myself, but I don't want any other Foreign Secretary of this country to be talked to or at by a Secretary of State in the United States as I have just had in my discussions with Mr Byrnes. We've got to have this thing over here whatever it costs .. We've got to have the bloody Union Jack on top of it." Penney did not have any knowledge of such committee until he was approached by Charles Portal, Marshal of the Air Force as well as the Chief of the Air Staff of the Royal Air Force, to lead the clandestine efforts.

The project was code-named High Explosive Research (or HER). In May 1947, Penney was appointed as the director to lead the programme, based at the Royal Armament Research Development Establishment (RARDE) at Fort Halstead and the Royal Arsenal at Woolwich (AWE). In short span of time, Penney assembled a team to initiate the work on atomic weapons, firstly preparing a report on describing the feature, science and idea of the U.S. plutonium implosion bomb (codename Fat Man). Penney broke down the development tasks required to replicate it, and identifying outstanding questions that required further research on nuclear weapons. The report entitled, "Plutonium Weapon - General Description" was roughly equivalent in terms of scientific data and reports that were provided to Soviet Union for their nuclear program by Klaus Fuchs.

In April 1950 an abandoned Second World War airfield, RAF Aldermaston in Berkshire was selected as the permanent home for Britain's nuclear weapons programme. This was to become the Atomic Weapons Research Establishment (AWRE). On 3 October 1952, under the code-name "Operation Hurricane", the first British nuclear device was successfully detonated off the west coast of Australia in the Monte Bello Islands. In 1958 the US-UK Mutual Defence Agreement was signed, providing for resumed nuclear weapons cooperation with the United States.