The Montreal Laboratory was a program established by the
National Research Council of Canada during
World War II
World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...
to undertake
nuclear research in collaboration with the
United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...
, and to absorb some of the scientists and work of the
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 Bri ...
nuclear project in Britain. It became part of the
Manhattan Project
The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada.
From 1942 to 1946, the ...
, and designed and built some of the world's first
nuclear reactor
A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons ...
s.
After the
Fall of France
The Battle of France (; 10 May – 25 June 1940), also known as the Western Campaign (), the French Campaign (, ) and the Fall of France, during the Second World War was the German invasion of the Low Countries (Belgium, Luxembourg and the Net ...
, some French scientists escaped to Britain with their stock of
heavy water
Heavy water (deuterium oxide, , ) is a form of water (molecule), water in which hydrogen atoms are all deuterium ( or D, also known as ''heavy hydrogen'') rather than the common hydrogen-1 isotope (, also called ''protium'') that makes up most o ...
. They were temporarily installed in the
Cavendish Laboratory
The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the School of Physical Sciences. The laboratory was opened in 1874 on the New Museums Site as a laboratory for experimental physics and is named ...
at the
University of Cambridge
The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...
, where they worked on reactor design. The
MAUD Committee was uncertain whether this was relevant to the main task of Tube Alloys, that of building an
atomic bomb
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear expl ...
, although there remained a possibility that a reactor could be used to breed
plutonium
Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...
, which might be used in one. It therefore recommended that they be relocated to the United States, and co-located with the Manhattan Project's reactor effort. Due to American concerns about security (many of the scientists were foreign nationals) and patent claims by the French scientists and
Imperial Chemical Industries
Imperial Chemical Industries (ICI) was a British Chemical industry, chemical company. It was, for much of its history, the largest manufacturer in Britain. Its headquarters were at Millbank in London. ICI was listed on the London Stock Exchange ...
(ICI), it was decided to relocate them to Canada instead.
The Canadian government agreed to the proposal, and the Montreal Laboratory was established in a house belonging to
McGill University
McGill University (French: Université McGill) is an English-language public research university in Montreal, Quebec, Canada. Founded in 1821 by royal charter,Frost, Stanley Brice. ''McGill University, Vol. I. For the Advancement of Learning, ...
; it moved to permanent accommodation at the
Université de Montréal
The Université de Montréal (; UdeM; ) is a French-language public research university in Montreal, Quebec, Canada. The university's main campus is located in the Côte-des-Neiges neighborhood of Côte-des-Neiges–Notre-Dame-de-Grâce on M ...
in March 1943. The first eight laboratory staff arrived in Montreal at the end of 1942. These were
Bertrand Goldschmidt and
Pierre Auger from France,
George Placzek from
Czechoslovakia
Czechoslovakia ( ; Czech language, Czech and , ''Česko-Slovensko'') was a landlocked country in Central Europe, created in 1918, when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland beca ...
, S. G. Bauer from Switzerland,
Friedrich Paneth and
Hans von Halban from Austria, and R. E. Newell and F. R. Jackson from Britain. The Canadian contingent included
George Volkoff,
Bernice Weldon Sargent and
George Laurence, and promising young Canadian scientists such as
J. Carson Mark,
Phil Wallace and
Leo Yaffe.
Although Canada was a major source of
uranium ore
Uranium ore deposits are economically recoverable concentrations of uranium within Earth's crust. Uranium is one of the most common Chemical element, elements in Earth's crust, being 40 times more common than silver and 500 times more common than ...
and heavy water, these were controlled by the Americans. Anglo-American cooperation broke down, denying the Montreal Laboratory scientists access to the materials they needed to build a reactor. In 1943, the
Quebec Agreement
The Quebec Agreement was a secret agreement between the United Kingdom and the United States outlining the terms for the coordinated development of the science and engineering related to nuclear power, nuclear energy and specifically nuclear we ...
merged Tube Alloys with the American Manhattan Project. The Americans agreed to help build the reactor. Scientists who were not British subjects left, and
John Cockcroft
Sir John Douglas Cockcroft (27 May 1897 – 18 September 1967) was an English nuclear physicist who shared the 1951 Nobel Prize in Physics with Ernest Walton for their splitting of the atomic nucleus, which was instrumental in the developmen ...
became the new director of the Montreal Laboratory in May 1944. The
Chalk River Laboratories
Chalk River Laboratories (; 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 a site of significant research and ...
opened in 1944, and the Montreal Laboratory was closed in July 1946. Two reactors were built at Chalk River. The small
ZEEP went critical on 5 September 1945, and the larger
NRX on 21 July 1947. NRX was for a time the most powerful
research reactor in the world.
Early nuclear research in Canada
Canada has a long history of involvement with nuclear research, dating back to the pioneering work of
Ernest Rutherford
Ernest Rutherford, 1st Baron Rutherford of Nelson (30 August 1871 – 19 October 1937) was a New Zealand physicist who was a pioneering researcher in both Atomic physics, atomic and nuclear physics. He has been described as "the father of nu ...
at
McGill University
McGill University (French: Université McGill) is an English-language public research university in Montreal, Quebec, Canada. Founded in 1821 by royal charter,Frost, Stanley Brice. ''McGill University, Vol. I. For the Advancement of Learning, ...
in 1899.
In 1940,
George Laurence of the
National Research Council (NRC) began experiments in
Ottawa
Ottawa is the capital city of Canada. It is located in the southern Ontario, southern portion of the province of Ontario, at the confluence of the Ottawa River and the Rideau River. Ottawa borders Gatineau, Gatineau, Quebec, and forms the cor ...
to measure
neutron capture
Neutron capture is a nuclear reaction in which an atomic nucleus and one or more neutrons collide and merge to form a heavier nucleus. Since neutrons have no electric charge, they can enter a nucleus more easily than positively charged protons, wh ...
and
nuclear fission
Nuclear fission is a reaction in which the nucleus of an atom splits into two or more smaller nuclei. The fission process often produces gamma photons, and releases a very large amount of energy even by the energetic standards of radioactiv ...
in
uranium
Uranium is a chemical element; it has chemical symbol, 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. Ura ...
to demonstrate the feasibility of a
nuclear reactor
A nuclear reactor is a device used to initiate and control a Nuclear fission, fission nuclear chain reaction. They are used for Nuclear power, commercial electricity, nuclear marine propulsion, marine propulsion, Weapons-grade plutonium, weapons ...
. For that purpose, he obtained of
uranium dioxide
Uranium dioxide or uranium(IV) oxide (), also known as urania or uranous oxide, is an oxide of uranium, and is a black, radioactive, crystalline powder that naturally occurs in the mineral uraninite. It is used in nuclear fuel rods in nuclear reac ...
in paper bags from the
Eldorado Mine at
Port Radium in the
Northwest Territories
The Northwest Territories is a federal Provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2021 census population of 41,070, it is the second-largest and the most populous of Provinces and territorie ...
. For a
neutron moderator
In nuclear engineering, a neutron moderator is a medium that reduces the speed of fast neutrons, ideally without capturing any, leaving them as thermal neutrons with only minimal (thermal) kinetic energy. These thermal neutrons are immensely ...
, he used
carbon
Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...
in the form of
petroleum coke
Petroleum coke, abbreviated coke, pet coke or petcoke, is a final carbon-rich solid material that derives from oil refinery, oil refining, and is one type of the group of fuels referred to as Coke (fuel), cokes. Petcoke is the coke that, in parti ...
. This was placed with the bags of uranium oxide in a large wooden bin lined with
paraffin wax
Paraffin wax (or petroleum wax) is a soft colorless solid derived from petroleum, coal, or oil shale that consists of a mixture of hydrocarbon molecules containing between 20 and 40 carbon atoms. It is solid at room temperature and melting poi ...
, another neutron moderator. A neutron source was added and a
Geiger counter
A Geiger counter (, ; also known as a Geiger–Müller counter or G-M counter) is an electronic instrument for detecting and measuring ionizing radiation with the use of a Geiger–Müller tube. It is widely used in applications such as radiat ...
used to measure
radioactivity
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...
.
The experiments continued in 1942, but were ultimately unsuccessful; the problems posed by impurities in the coke and uranium oxide had not been fully appreciated, and as a result too many neutrons were captured. But Laurence's efforts attracted some attention, and in the summer of 1940 he was visited by
R. H. Fowler,
the British scientific liaison officer in Canada. This was followed by a visit from
John Cockcroft
Sir John Douglas Cockcroft (27 May 1897 – 18 September 1967) was an English nuclear physicist who shared the 1951 Nobel Prize in Physics with Ernest Walton for their splitting of the atomic nucleus, which was instrumental in the developmen ...
of the British
Tizard Mission
The Tizard Mission, officially the British Technical and Scientific Mission, was a delegation from the United Kingdom that visited the United States during World War II to share secret research and development (R&D) work that had military applicat ...
to the United States in the autumn. They brought news of the similar research being carried out under the supervision of the
MAUD Committee in Britain and the
National Defense Research Committee
The National Defense Research Committee (NDRC) was an organization created "to coordinate, supervise, and conduct scientific research on the problems underlying the development, production, and use of mechanisms and devices of warfare" in the U ...
(NDRC) in the United States.
Fowler became the channel of communication between the NDRC and its counterparts in Britain and Canada. Through him, Laurence obtained an introduction to
Lyman J. Briggs, the chairman of the NDRC's
S-1 Uranium Committee, who supplied copies of American studies.
On returning to England, Cockcroft arranged through
Lord Melchett for Laurence to receive a $5,000 grant to continue his research. This payment was made by
Imperial Chemical Industries
Imperial Chemical Industries (ICI) was a British Chemical industry, chemical company. It was, for much of its history, the largest manufacturer in Britain. Its headquarters were at Millbank in London. ICI was listed on the London Stock Exchange ...
(ICI) through a Canadian subsidiary. It had the desired side effect of impressing the Canadian authorities with the importance of Laurence's work.
French connection
Laurence had chosen to use carbon instead of
heavy water
Heavy water (deuterium oxide, , ) is a form of water (molecule), water in which hydrogen atoms are all deuterium ( or D, also known as ''heavy hydrogen'') rather than the common hydrogen-1 isotope (, also called ''protium'') that makes up most o ...
because it was cheaper and more readily available.
A team of scientists in France that included
Hans von Halban,
Lew Kowarski
Lew Kowarski (10 February 1907 – 30 July 1979) was a Russian-French physicist. He was a lesser-known but important contributor to nuclear science. He participated in the British Tube Alloys on early nuclear weapon research. After the war he wor ...
, and
Francis Perrin had been conducting similar experiments since 1939. By 1940, they had decided to use heavy water as a moderator, and through the French
Minister of Armaments obtained about from the
Norsk Hydro
Norsk Hydro ASA (often referred to as just ''Hydro'') is a Norway, Norwegian aluminium and renewable energy company, headquartered in Oslo. It is one of the largest aluminium companies worldwide. It has operations in some 50 countries around th ...
hydroelectric station at
Vemork
Vemork is a hydroelectric power plant outside the town of Rjukan in Tinn Municipality in Telemark county, Norway. The plant was built by Norsk Hydro and opened in 1911, its main purpose being to fix nitrogen for the production of fertilizer. ...
in Norway. After the
Fall of France
The Battle of France (; 10 May – 25 June 1940), also known as the Western Campaign (), the French Campaign (, ) and the Fall of France, during the Second World War was the German invasion of the Low Countries (Belgium, Luxembourg and the Net ...
, they had escaped to Britain with their stock of heavy water. They were temporarily installed in the
Cavendish Laboratory
The Cavendish Laboratory is the Department of Physics at the University of Cambridge, and is part of the School of Physical Sciences. The laboratory was opened in 1874 on the New Museums Site as a laboratory for experimental physics and is named ...
at the
University of Cambridge
The University of Cambridge is a Public university, public collegiate university, collegiate research university in Cambridge, England. Founded in 1209, the University of Cambridge is the List of oldest universities in continuous operation, wo ...
but, believing that Britain would soon fall as well, were eager to relocate to the United States or Canada.
Canada was an alternative source of heavy water.
Cominco had been involved in heavy water research since 1934, and produced it at its smelting plant in
Trail, British Columbia
Trail is a city in the western Kootenays region of the British Columbia Interior, Interior of British Columbia, Canada. It was named after the Dewdney Trail, which passed through the area. The town was first called Trail Creek or Trail Creek Lan ...
. On 26 February 1941, the NRC inquired about its ability to produce heavy water. This was followed on 23 July by a letter from
Hugh Taylor, a British-born scientist working at
Princeton University
Princeton University is a private university, private Ivy League research university in Princeton, New Jersey, United States. Founded in 1746 in Elizabeth, New Jersey, Elizabeth as the College of New Jersey, Princeton is the List of Colonial ...
, on behalf of the
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 ...
(OSRD). Taylor offered a NDRC contract to produce , for which the NDRC was prepared to pay $5 per pound for low-grade and $10 for high-grade heavy water. At the time it was selling for up to $1,130 per pound.
Cominco's president,
Selwyn G. Blaylock, was cautious. There might be no post-war demand for heavy water, and the
patent
A patent is a type of intellectual property that gives its owner the legal right to exclude others from making, using, or selling an invention for a limited period of time in exchange for publishing an sufficiency of disclosure, enabling discl ...
on the process was held by Albert Edgar Knowles, so a profit-sharing agreement would be required. In response, Taylor offered $20,000 for plant modifications.
There the matter rested until 6 December, when Blaylock had a meeting with the British physicist G. I. Higson, who informed him that Taylor had become discouraged with Cominco, and had decided to find another source of heavy water. Blaylock invited Taylor to visit Trail, which he did from 5 to 8 January 1942. The two soon found common ground. Blaylock agreed to produce heavy water at Trail, and quickly secured approval from the chairman of the board, Sir
Edward Beatty. A contract was signed on 1 August 1942. The heavy water project became known as the
P-9 Project in October 1942.
The French scientists made good progress on the design of an
aqueous homogeneous reactor
Aqueous homogeneous reactors (AHR) is a two (2) chamber reactor consisting of an interior reactor chamber and an outside cooling and moderating jacket chamber. They are a type of nuclear reactor in which soluble nuclear salts (usually uranium su ...
, but there were doubts that their work was relevant to the main task of the British
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 Bri ...
project, that of building an
atomic bomb
A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission or atomic bomb) or a combination of fission and fusion reactions (thermonuclear weapon), producing a nuclear expl ...
, and resources were tightly controlled in wartime Britain. There was a possibility that a reactor could be used to breed
plutonium
Plutonium is a chemical element; it has symbol Pu and atomic number 94. It is a silvery-gray actinide metal that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibits six allotropes and four ...
, but its use in a bomb seemed a remote possibility. The MAUD Committee therefore felt that they should relocate to America. It made sense to pool resources, and America had advantages, notably access to materials such as heavy water. American scientists such as
Henry D. Smyth, Harold Urey and Hugh Taylor urged that the Cambridge team be sent to America. On the other hand, American officials had concerns about security, since only one of the six senior scientists in the Cambridge group was British, and about French patent claims.
These included patents on controlling nuclear chain reactions, enriching uranium, and using
deuterium
Deuterium (hydrogen-2, symbol H or D, also known as heavy hydrogen) is one of two stable isotopes of hydrogen; the other is protium, or hydrogen-1, H. The deuterium nucleus (deuteron) contains one proton and one neutron, whereas the far more c ...
as a neutron moderator. There were also two patent applications in conjunction with
Egon Bretscher
Egon Bretscher (23 May 1901 – 16 April 1973) was a Swiss-born British chemist and nuclear physicist and Head of the Nuclear Physics Division from 1948 to 1966 at the Atomic Energy Research Establishment, also known as Harwell Laboratory, in ...
and
Norman Feather on the production and use of plutonium.
George Thomson George Thomson may refer to:
Government and politics
* George Thomson (MP for Southwark) (c. 1607–1691), English merchant and Parliamentarian soldier, official and politician
* George Thomson, Baron Thomson of Monifieth (1921–2008), Scottish p ...
, the chairman of the MAUD Committee, suggested a compromise: relocating the team to Canada.
Establishment
The next step was to broach the matter with the Canadians. The
Lord President, Sir
John Anderson, as the
minister responsible for Tube Alloys, wrote to the British
High Commissioner to Canada,
Malcolm MacDonald
Malcolm John MacDonald (17 August 1901 – 11 January 1981) was a British politician and diplomat. He was initially a Labour Party (UK), Labour Member of Parliament (United Kingdom), Member of Parliament (MP), but in 1931 followed his father ...
, who had been involved in Tube Alloys negotiations with Canada regarding
Eldorado's uranium mine at Port Radium and its refinery in
Port Hope, Ontario
Port Hope is a municipality in Southern Ontario, Canada, about east of Toronto and west of Kingston, Ontario, Kingston. It is at the mouth of the Ganaraska River on the north shore of Lake Ontario, in the west end of Northumberland County, Onta ...
. On 19 February 1942, MacDonald, Thomson and Wallace Akers, the director of Tube Alloys, met with
C. J. Mackenzie, the president of the NRC, who enthusiastically supported the proposal. The following day he took them to see
C. D. Howe, the
Minister of Munitions and Supply.

Howe cabled Anderson expressing the Canadian government's agreement in principle, but requesting a more detailed appraisal of the cost of the proposed laboratory. Sir John Anderson replied that he envisaged a laboratory with about 30 scientists and 25 laboratory assistants, of whom 22 scientists and 6 laboratory assistants would be sent from Britain. The estimated running cost was £60,000 per annum. He agreed that the costs and salaries would be divided between the British and Canadian governments, but the British share would come from a billion-dollar war gift from Canada. The Canadians found this acceptable. Howe and Mackenzie then travelled to London to finalise arrangements for the laboratory's governance. It was agreed that it would be run by a Policy Committee consisting of Howe and MacDonald and be administered by and funded through the NRC, with research directed by a Technical Committee chaired by Halban.
The Canadians decided that the new laboratory should be located in Montreal, where housing accommodation was easier to find than in wartime Ottawa. They hoped to have everything ready by 1 January 1943, but negotiations for laboratory space fell through. A search then commenced for an alternative location.
Bertrand Goldschmidt, a French scientist who was already in Canada, ran into
Henri Laugier, a French biologist who had been president of the ''
Centre national de la recherche scientifique
The French National Centre for Scientific Research (, , CNRS) is the French state research organisation and is the largest fundamental science agency in Europe.
In 2016, it employed 31,637 staff, including 11,137 tenured researchers, 13,415 eng ...
'' before the Fall of France, when he had escaped to Canada. Laugier suggested that they acquire some unused wings of a new building at the
Université de Montréal
The Université de Montréal (; UdeM; ) is a French-language public research university in Montreal, Quebec, Canada. The university's main campus is located in the Côte-des-Neiges neighborhood of Côte-des-Neiges–Notre-Dame-de-Grâce on M ...
, where he was now teaching. These had been earmarked for a medical school, but had never been equipped due to a lack of funds.
The space was acquired, but considerable work was required to convert it into a laboratory, and it could not be made ready before mid-February 1943.
Ernest Cormier, the university architect, drew up the plans.
The first eight staff arrived in Montreal at the end of 1942. These were Goldschmidt and
Pierre Auger from France,
George Placzek from
Czechoslovakia
Czechoslovakia ( ; Czech language, Czech and , ''Česko-Slovensko'') was a landlocked country in Central Europe, created in 1918, when it declared its independence from Austria-Hungary. In 1938, after the Munich Agreement, the Sudetenland beca ...
, S. G. Bauer from Switzerland,
Friedrich Paneth and Halban from Austria, and R. E. Newell and F. R. Jackson from Britain. The
Battle of the Atlantic
The Battle of the Atlantic, the longest continuous military campaign in World War II, ran from 1939 to the defeat of Nazi Germany in 1945, covering a major part of the naval history of World War II. At its core was the Allies of World War II, ...
was still raging, and men and equipment, which travelled separately, were at risk from German
U-boat
U-boats are Submarine#Military, naval submarines operated by Germany, including during the World War I, First and Second World Wars. The term is an Anglicization#Loanwords, anglicized form of the German word , a shortening of (), though the G ...
s. The scientists occupied a house at 3470 Simpson Street in downtown Montreal that belonged to McGill University.
This soon became so crowded that bathrooms were used for offices, with the bath tubs used to store papers and books. They were relieved to move to the more spacious accommodation at the Université de Montréal in March. The laboratory grew to over 300 staff, about half of whom were Canadians recruited by Laurence.
Placzek became head of the theoretical physics division. Kowarski was designated to be the head of the experimental physics division, but there was a personality clash with Halban, and Kowarski did not wish to accept what he saw as a subordinate position under Halban. At this point, many other scientists said that they would not go without Kowarski, but Sir
Edward Appleton, the
permanent secretary
A permanent secretary is the most senior Civil Service (United Kingdom), civil servant of a department or Ministry (government department), ministry charged with running the department or ministry's day-to-day activities. Permanent secretaries are ...
of the British
Department of Scientific and Industrial Research, of which the Tube Alloys was a part, managed to persuade them to go. Kowarski remained at Cambridge, where he worked for
James Chadwick
Sir James Chadwick (20 October 1891 – 24 July 1974) was an English nuclear physicist who received the Nobel Prize in Physics in 1935 for his discovery of the neutron. In 1941, he wrote the final draft of the MAUD Report, which inspired t ...
. Auger became head of the experimental physics division instead.
Paneth became head of the chemistry division. Two other scientists that had escaped from France joined the laboratory: the French chemist
Jules Guéron, who had been working for
Free France
Free France () was a resistance government
claiming to be the legitimate government of France following the dissolution of the Third French Republic, Third Republic during World War II. Led by General , Free France was established as a gover ...
at Cambridge, and
Bruno Pontecorvo
Bruno Pontecorvo (; , ''Bruno Maksimovich Pontecorvo''; 22 August 1913 – 24 September 1993) was an Italian–Russian nuclear physicist, an early assistant of Enrico Fermi and the author of numerous studies in high energy physics, especially o ...
, an Italian scientist who had worked with
Enrico Fermi
Enrico Fermi (; 29 September 1901 – 28 November 1954) was an Italian and naturalized American physicist, renowned for being the creator of the world's first artificial nuclear reactor, the Chicago Pile-1, and a member of the Manhattan Project ...
in Italy before the war.
For the Canadian contingent, Laurence and Mackenzie set out to recruit some top nuclear physicists, of whom there were few in Canada. The first was
George Volkoff at the
University of British Columbia
The University of British Columbia (UBC) is a Public university, public research university with campuses near University of British Columbia Vancouver, Vancouver and University of British Columbia Okanagan, Kelowna, in British Columbia, Canada ...
, who had worked with
Robert Oppenheimer
J. Robert Oppenheimer (born Julius Robert Oppenheimer ; April 22, 1904 – February 18, 1967) was an American theoretical physicist who served as the director of the Manhattan Project's Los Alamos Laboratory during World War II. He is often ...
on the physics of
neutron star
A neutron star is the gravitationally collapsed Stellar core, core of a massive supergiant star. It results from the supernova explosion of a stellar evolution#Massive star, massive star—combined with gravitational collapse—that compresses ...
s. They also tried to recruit
Harry Thode from
McMaster University
McMaster University (McMaster or Mac) is a public research university in Hamilton, Ontario, Canada. The main McMaster campus is on of land near the residential neighbourhoods of Ainslie Wood, Ontario, Ainslie Wood and Westdale, Ontario, Westd ...
, but found that Harold Urey from the
Manhattan Project
The Manhattan Project was a research and development program undertaken during World War II to produce the first nuclear weapons. It was led by the United States in collaboration with the United Kingdom and Canada.
From 1942 to 1946, the ...
's
SAM Laboratories was also interested in Thode's expertise in testing heavy water with
mass spectrography, and had made a more attractive offer. A compromise was reached whereby Thode did work for the Montreal Laboratory, but remained at McMaster University. Promising young Canadian scientists were also recruited, including
J. Carson Mark,
Phil Wallace and
Leo Yaffe.
Research

The Montreal Laboratory investigated multiple avenues of reactor development. One was a homogeneous reactor, in which a uranium compound was dissolved in heavy water to form a
slurry
A slurry is a mixture of denser solids suspended in liquid, usually water. The most common use of slurry is as a means of transporting solids or separating minerals, the liquid being a carrier that is pumped on a device such as a centrifugal pu ...
, or a "mayonnaise" as the Montreal team called it. This offered various advantages for cooling, control and the ability to draw off plutonium that was produced. Paneth, Goldschmidt and others experimented with methods of preparing such a uranium compound, but none could be found with the required density. They considered using
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 (23 ...
, but it was unavailable. Attention then turned to a heterogeneous reactor, in which a lattice of uranium metal rods were immersed in heavy water. While much less heavy water would be required, there was a danger that the water would decompose into deuterium and oxygen—a potentially explosive combination. There was great interest in
breeder reactor
A breeder reactor is a nuclear reactor that generates more fissile material than it consumes. These reactors can be fueled with more-commonly available isotopes of uranium and thorium, such as uranium-238 and thorium-232, as opposed to the ...
s, which could breed plutonium from uranium or
uranium-233
Uranium-233 ( or U-233) is a fissile isotope of uranium that is bred from thorium-232 as part of the thorium fuel cycle. Uranium-233 was investigated for use in nuclear weapons and as a Nuclear fuel, reactor fuel. It has been used successfully ...
from
thorium
Thorium is a chemical element; it has symbol Th and atomic number 90. Thorium is a weakly radioactive light silver metal which tarnishes olive grey when it is exposed to air, forming thorium dioxide; it is moderately soft, malleable, and ha ...
, as it was believed that uranium was scarce. A process was devised for separating the uranium from thorium.
To build a working nuclear reactor, the Montreal Laboratory depended on the Americans for heavy water from Trail, which was under American contract, but this was not forthcoming. An American request for Halban to come to New York to discuss heavy water with Fermi and Urey was turned down by the British, and the Americans brought cooperation to a standstill. By June 1943 work at the Montreal Lab had come to a halt. Morale was low and the Canadian Government proposed cancelling the project.
The British government seriously considered going it alone on developing nuclear weapons, despite the cost and the expected length of the project. In August 1943, Canadian Prime Minister
Mackenzie King
William Lyon Mackenzie King (December 17, 1874 – July 22, 1950) was a Canadian statesman and politician who was the tenth prime minister of Canada for three non-consecutive terms from 1921 to 1926, 1926 to 1930, and 1935 to 1948. A Liberal ...
hosted the
Quebec Conference, at which
Winston Churchill
Sir Winston Leonard Spencer Churchill (30 November 1874 – 24 January 1965) was a British statesman, military officer, and writer who was Prime Minister of the United Kingdom from 1940 to 1945 (Winston Churchill in the Second World War, ...
and
Franklin D. Roosevelt
Franklin Delano Roosevelt (January 30, 1882April 12, 1945), also known as FDR, was the 32nd president of the United States, serving from 1933 until his death in 1945. He is the longest-serving U.S. president, and the only one to have served ...
came together, and agreed to resume cooperation. The
Quebec Agreement
The Quebec Agreement was a secret agreement between the United Kingdom and the United States outlining the terms for the coordinated development of the science and engineering related to nuclear power, nuclear energy and specifically nuclear we ...
subsumed Tube Alloys into the Manhattan Project, and established the
Combined Policy Committee, on which Canada was represented by Howe, to control the Manhattan Project.
While some aspects of cooperation resumed quickly, it took longer to finalize the details with respect to the Montreal Laboratory.
Brigadier General Leslie Groves
Leslie Richard Groves Jr. (17 August 1896 – 13 July 1970) was a United States Army Corps of Engineers officer who oversaw the construction of the Pentagon and directed the Manhattan Project, a Classified information#Top_Secret_(TS), top sec ...
(the director of the Manhattan Project), Chadwick (now the head of the
British Mission to the Manhattan Project), and Mackenzie negotiated recommendations, which were approved by the Combined Policy Committee on 13 April 1944. A final agreement was spelt out on 20 May. Under it, the Americans would assist with the construction of a heavy water reactor in Canada, and would provide technical assistance with matters such as corrosion and the effects of radiation on materials. They would not provide details about plutonium or plutonium chemistry, although irradiated uranium slugs would be made available for the British to work it out for themselves. The Americans had already built their own heavy water reactor,
Chicago Pile-3, which went critical in May 1944. The September 1944
Hyde Park Agreement extended both commercial and military cooperation into the post-war period.
Hans von Halban had proved to be an unfortunate choice as he was a poor administrator, and did not work well with Mackenzie or the NRC. The Americans saw him as a security risk, and objected to the French atomic patents claimed by the Paris Group (in association with ICI). In April 1944 a Combined Policy Committee meeting at Washington agreed that Canada would build a heavy water reactor. Scientists who were not British subjects would leave, and Cockcroft became the new director of the Montreal Laboratory in May 1944.
E. W. R. Steacie became assistant director and head of the Chemistry division when Paneth left. Volkoff eventually succeeded Placzek as head of the Theoretical Physics division. Halban remained as head of the nuclear physics division.

After the
Liberation of Paris
The liberation of Paris () was a battle that took place during World War II from 19 August 1944 until the German garrison surrendered the French capital on 25 August 1944. Paris had been occupied by Nazi Germany since the signing of the Armisti ...
in August 1944, the French scientists wanted to go home. Auger had already returned to London to join the French Scientific Mission in April 1944. Halban returned on a visit to London and Paris in November 1944, where he saw
Frédéric Joliot-Curie
Jean Frédéric Joliot-Curie (; ; 19 March 1900 – 14 August 1958) was a French chemist and physicist who received the 1935 Nobel Prize in Chemistry with his wife, Irène Joliot-Curie, for their discovery of induced radioactivity. They were t ...
for the first time since leaving France. While he maintained that he did not divulge any nuclear secrets to his previous boss (although he had discussed patent rights), Halban was not allowed to work or to leave North America for a year, although he left the Montreal Laboratory in April 1945. In 1946 he settled in England.
B. W. Sargent then became head of the nuclear physics division.
Cockcroft arranged for Goldschmidt, Guéron and Kowarski to remain until June 1945, later extended until the end of 1945. Goldschmidt was willing to stay longer, and Cockcroft wanted to keep him, but Groves insisted that he should go, and, in the interest of Allied harmony, he did. All the French scientists had left by January 1946.
On 24 August 1944, the decision was taken to build a small reactor to test the group's calculations relating to such matters as lattice dimensions, sheathing materials, and
control rods, before proceeding with the full-scale
NRX reactor.
With Halban gone, Kowarski joined the laboratory, and was given responsibility for the small reactor, which he named
ZEEP, for Zero Energy Experimental Pile. He was assisted in the design by Charles Watson-Munro from New Zealand, and
George Klein and Don Nazzer from Canada.
Building reactors in downtown Montreal was out of the question; the Canadians selected, and Groves approved, a site at
Chalk River
Chalk River (2016 population: 1029) is a community located within the town of Laurentian Hills in Renfrew County, Ontario, Canada. It is located in the Upper Ottawa Valley along Highway 17 (Ontario), Highway 17 (Trans-Canada Highway), inland ...
, Ontario, on the south bank of the
Ottawa River
The Ottawa River (, ) is a river in the Canadian provinces of Ontario and Quebec. It is named after the Algonquin word "to trade", as it was the major trade route of Eastern Canada at the time. For most of its length, it defines the border betw ...
some northwest of Ottawa.
The Americans fully supported the reactor project with information and visits. Groves loaned the Montreal Laboratory of heavy water and of pure uranium metal for the reactor, and samples of pure and irradiated uranium and thorium to develop the extraction process. The irradiated materials came from the Manhattan Project's
X-10 Graphite Reactor at the
Clinton Engineer Works at Oak Ridge, Tennessee. Some of machined pure uranium rods was sold outright to Canada. He also supplied instruments, drawings and technical information, provided expertise from American scientists, and opened a liaison office in Montreal headed by Major H. S. Benbow. The American physicist
William Weldon Watson from the
Metallurgical Laboratory and chemist John R. Huffman from the SAM Laboratories were assigned to it. They were succeeded by
George Weil in November 1945.
Benbow was succeeded by Major P. Firmin in December 1945, who in turn was replaced by Colonel A. W. Nielson in February 1946.
The
Chalk River Laboratories
Chalk River Laboratories (; 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 a site of significant research and ...
opened in 1944, and the Montreal Laboratory was closed in July 1946.
ZEEP went critical on 5 September 1945, becoming the first operating nuclear reactor outside the United States. Using of heavy water and of uranium metal, it could operate continuously at 3.5 W, or for brief periods at 30 to 50 W. The larger NRX followed on 21 July 1947. With five times the
neutron flux
The neutron flux is a scalar quantity used in nuclear physics and nuclear reactor physics. It is the total distance travelled by all free neutrons per unit time and volume. Equivalently, it can be defined as the number of neutrons travelling ...
of any other reactor, it was the most powerful
research reactor in the world.
Originally designed in July 1944 with an output of 8 MW, the power was raised to 10 MW through design changes such as replacing uranium rods clad in stainless steel and cooled by heavy water with aluminium-clad rods cooled by light water.
By the end of 1946, the Montreal Laboratory was estimated to have cost US$22,232,000, excluding the cost of the heavy water. The NRX reactor provided Britain, the United States and Canada with a source of fissile plutonium and uranium-233. It also provided a means of efficiently producing medical isotopes like
phosphorus-32
Phosphorus-32 (32P) is a radioactive isotope of phosphorus. The nucleus of phosphorus-32 contains 15 protons and 17 neutrons, one more neutron than the most common isotope of phosphorus, phosphorus-31. Phosphorus-32 only exists in small quantiti ...
, research facilities that for a time were superior to those in the United States, and a wealth of technical information related to reactor design and operation. With the passage of the Canadian Atomic Energy Act of 1946, the responsibility for the Chalk River Laboratories passed to the
Atomic Energy Control Board
The Canadian Nuclear Safety Commission (CNSC; ) is the federal regulator of nuclear power and materials in Canada.
Mandate and history
Canadian Nuclear Safety Commission was established under the 1997 '' Nuclear Safety and Control Act'' with a ma ...
.
Atomic spies
On 5 September 1945,
Igor Gouzenko
Igor Sergeyevich Gouzenko (; ; January 26, 1919 – June 25, 1982) was a cipher clerk for the Soviet embassy to Canada in Ottawa, Ontario, and a lieutenant of the Soviet Main Intelligence Directorate (GRU). He defected on September 5, 1945, th ...
, a
cypher clerk at the
Soviet Union
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
's embassy in Ottawa, and his family
defected
In politics, a defector is a person who gives up allegiance to one state in exchange for allegiance to another, changing sides in a way which is considered illegitimate by the first state. More broadly, defection involves abandoning a person, ca ...
to Canada. He brought with him copies of cables detailing
Soviet intelligence (GRU) espionage activities in Canada. Agents included
Alan Nunn May, who secretly supplied tiny samples of uranium-233 and
uranium-235
Uranium-235 ( 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 exists in nat ...
to GRU agent Pavel Angelov in July 1945;
Fred Rose, a
member of parliament; and NRC scientists
Israel Halperin, Edward Mazerall and Durnford Smith. Pontecorvo, who defected to the Soviet Union in 1950, has long been suspected of having been involved in espionage. No evidence that he was a Soviet agent has ever been established, but the GRU obtained samples of uranium and blueprints of the NRX, for which Nunn May could not have been the source, and Pontecorvo remains the prime suspect. When the spy ring became public knowledge in February 1946, the Americans became more cautious about sharing information with Britain and Canada.
Cooperation ends

The Montreal Laboratory had been a fruitful and successful international venture, although the Canadians had on occasion been resentful of British actions that were perceived as high-handed and insensitive. One such action came in November 1945 when the British government suddenly announced that Cockcroft had been appointed the head of the new
Atomic Energy Research Establishment
The Atomic Energy Research Establishment (AERE), also known as Harwell Laboratory, was the main Headquarters, centre for nuclear power, atomic energy research and development in the United Kingdom from 1946 to the 1990s. It was created, owned ...
in Britain without any prior consultation and at a time when the NRX reactor was still under construction. Cockcroft did not depart Canada until September 1946, but it was a sure sign of waning British interest in collaboration with Canada. The British suggested he be replaced by the British physicist
Bennett Lewis, who was eventually appointed, but only after the Canadian-born
Walter Zinn turned the job down.
Anglo-American cooperation did not long survive the war. Roosevelt died on 12 April 1945, and the Hyde Park Agreement was not binding on subsequent administrations. The
Special Relationship
The Special Relationship is an unofficial term for relations between the United Kingdom and the United States.
Special Relationship also may refer to:
* Special relationship (international relations), other exceptionally strong ties between nat ...
between Britain and the United States "became very much less special". The British government had trusted that America would share nuclear technology, which the British considered a joint discovery. On 9 November 1945, Mackenzie King and British Prime Minister
Clement Attlee
Clement Richard Attlee, 1st Earl Attlee (3 January 18838 October 1967) was a British statesman who was Prime Minister of the United Kingdom from 1945 to 1951 and Leader of the Labour Party (UK), Leader of the Labour Party from 1935 to 1955. At ...
went to Washington, D.C., to confer with President
Harry Truman
Harry S. Truman (May 8, 1884December 26, 1972) was the 33rd president of the United States, serving from 1945 to 1953. As the 34th vice president in 1945, he assumed the presidency upon the death of Franklin D. Roosevelt that year. Subsequen ...
about future cooperation in nuclear weapons and nuclear power. A Memorandum of Intention that replaced the Quebec Agreement made Canada a full partner. The three leaders agreed that there would be full and effective cooperation, but British hopes for a resumption of cooperation on nuclear weapons were in vain. The Americans soon made it clear that cooperation was restricted to basic scientific research.
At the Combined Policy Committee meeting in February 1946, without prior consultation with Canada, the British announced their intention to build a
graphite-moderated nuclear reactor in the United Kingdom. An outraged Howe told Canadian ambassador
Lester B. Pearson
Lester Bowles Pearson (23 April 1897 – 27 December 1972) was a Canadian politician, diplomat, statesman, and scholar who served as the 14th prime minister of Canada from 1963 to 1968. He also served as Leader of the Liberal Party of C ...
to inform the committee that nuclear cooperation between Britain and Canada was at an end. The Canadians had been given what they deemed assurances that the Chalk River Laboratories would be a joint enterprise, and regarded the British decision as a breach of faith. Anglo-American cooperation largely ended in April 1946 when Truman declared that the United States would not assist Britain in the design, construction or operation of a plutonium production reactor. The Americans had agreed that such a facility could be built in Canada, but the British were not willing to be dependent on Canada for the supply of
fissile
In nuclear engineering, fissile material is material that can undergo nuclear fission when struck by a neutron of low energy. A self-sustaining thermal Nuclear chain reaction#Fission chain reaction, chain reaction can only be achieved with fissil ...
material.
Notes
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