and Its Evolution to Chalk River
The Canadian nuclear timeline that led to the development of CANDU had its beginnings in what are referred to as the “Montreal Labs”. The history is very well documented in an excellent book by Wilfred Eggelston titled “Canada’s Nuclear Story”. This book was published in 1965 but few people may now have access to it. The following article draws very heavily from this book and is intended to be a much-condensed, but available, “history” – Eggelston covers the same ground in great detail in his book in about 150 pages.
The discovery of fission and its potential as an energy source, both destructive and peaceful, was initially a European story. Famous names like Antoine Henri Becquerel in Paris (discoverer of radioactivity in 1896) and Marie Sklodowska and Pierre Curie in France (discovery of radioactivity in thorium, polonium and radium in 1898) in the late 1800s started the field of nuclear physics. These discoveries were followed by outstanding work by numerous others such as Ernest Rutherford, James Chadwick and Niels Henrik David Bohr and led in 1934-1938 era to the discovery and understanding of uranium fission by European groups led by Irene Joliet-Curie and Paul Savitch (Paris) and Otto Hahn and Fredrich Wilhelm Strausmann (Berlin). The discoveries first reached the publication stage in 1939 with papers by a number of authors including Lise Meitner and Otto Robert Frisch.
On the day of the publication of the Meitner-Frisch paper in the periodical Nature, Bohn travelled to the USA to attend some meetings and began to spread the word of the discovery and explanation of the results to North America. Ten days later he presented the results at a conference. His report immediately started an exodus from the conference as attendees rushed to their laboratories to try to reproduce the observations.
The storm clouds of the impending armed conflicts in Europe in 1938-1939 had an enormous effect on the future work on fission. It was recognized that the possibility of a new devasting weapon of war existed. Furthermore, it was recognized that many of the researchers in mainland Europe were in danger of capture and detention by the Nazi regime. Many fled Europe to England and North America taking with them their knowledge. The prospects of the development of a dreadful weapon also led to a chill on publication of experimental results.
Of particular interest to the Canadian story is the exodus from Europe of expertise and materials related to heavy water. In early 1939 Hans-Heinrich von Halban and Lew Kowarski were part of a French group who recognized that heavy water might be an excellent moderator to slow down the fast neutrons expected from the fission of uranium atoms. Only small amounts of this material were known to exist and world production was from a single plant in Norway. It was calculated that tons of heavy water would be needed for a self-sustaining chain reaction but less that 200 kilograms was known to exist. The Nazis had begun their military campaign in northern Europe but a French group was able to smuggle the main world supply of heavy water (187 litres) out of Norway in time. The story of this effort has been the subject of a number of books and films. Halban and Kowarski fled to England from France shortly after this adventure taking their knowledge and the precious supply of heavy water with them.
In Canada, George Craig Laurence, working at the National Research Council (NRC) laboratories in Ottawa, learned about fission from the initial publications of 1939. He completed a series of calculations that suggested a sustained reaction might be achievable with materials available in Canada. Primarily, his need was for uranium and a suitable moderator. Canada was a world-leading source of uranium ore at that time – used mainly for the extraction of radium (for treating cancer) at Port Hope. Uranium oxide was being treated as an unwanted, nuisance by-product and was readily available. Laurence realized the value of heavy water as a potential moderator but, because of its scarcity, was forced to experiment instead with carbon. He was able to obtain a substantial quantity of relatively pure calcinated coke used in the manufacture of graphite. Both of his key materials were of uncertain purity.
Work began in early 1940 at the NRC on Sussex Drive in Ottawa under a curtain of secrecy – the war was now on. The preliminary attempts at constructing a suitable “pile” with the uranium oxide and carbon were conducted mainly on weekends as Laurence juggled other tasks at NRC vital to the war effort. In early 1941 he was able to convince Bernice Weldon Sargent of Queen’s University to join him in these experiments. They built a spherical pile roughly 140 cm in diameter consisting of bags of uranium oxide and of carbon all packed in paper bags and arranged in a lattice arrangement. For a neutron source, located in the middle of the pile, they used a mixture of beryllium and around 200 mg of radium. Alas however, impurities in both the uranium and the carbon were sufficiently a problem that, although valuable data were obtained, these impurities precluded a successful culmination to their experiments.
Larger quantities of materials of significantly higher purity (including uranium metal as opposed to oxide) were becoming available to the better-resourced experimenters in the USA; the first successful sustained reaction with a uranium/carbon matrix was achieved in December 1942 in Chicago by the group led by Enrico Fermi instead of the Laurence-Sargent team in Ottawa.
The Anglo-American-Canadian Collaboration
The war years of 1940-1941 would be very difficult years for the British (the USA did not enter the war until 8 December 1941). It was realized quickly that it would be very difficult for the British scientists, even though bolstered by a large group of talented nuclear physicists who had fled from mainland Europe, to make significant advances on the research towards an “atomic weapon” in Britain. In early 1940 a group under the cover name of the MAUD Commission and chaired by George Paget Thomson was set up to study the concept. They were joined shortly by von Halban and Kowarski who arrived from France with their precious cargo of heavy water. While the concept of the weapon gained increasing credence, the realization grew that it would most likely have to be pursued in North America.
Work in the USA, where the nuclear research programs were also being bolstered by emigres from Europe, was also gaining speed and in mid-1941 Vannebar Bush and James Bryant Conant, top advisors to the USA government on defence matters, proposed an Anglo-American co-operative effort on the development of a bomb.
In the fall of 1941 a new organization, under the name of “Tube Alloys” was formed in Britain under Edward Victor Appleton. This organization was placed under a government department but also included key members from Imperial Chemical Industries (ICI), a large private company. Early in 1942, Wallace Akers of Tube Alloys travelled to the USA to investigate further prospects for a combined Anglo-American effort, possibly in Chicago. He also made a side trip to Ottawa to see Chalmers Jack Mackenzie, President of the NRC.
Since a large stockpile of surplus uranium oxide existed in Canada, it was realized that Canada could also play a role in this effort. The USA had recognized the presence of this stockpile somewhat earlier and had taken initial steps towards acquiring it. The stockpile was owned by Eldorado Mining Ltd. and there were discussions in Ottawa about a possible purchase of the company holdings by the Canadian government.
A second key element in the efforts toward research on the bomb was a supply of heavy water. The world supply at that time was in the hands of von Halban and Kowarski in Britain. The USA had begun in 1941 to look for a new source and in the summer of 1942 placed a $2.5M contract with Consolidated Mining and Smelting Company in Trail, BC, for the production of heavy water as a side stream to their electrolytic hydrogen process for the production of ammonia. (A year later work was started in the USA on three additional heavy water manufacturing facilities.) In mid-1942, Canada was thus the source country for the major materials needed for a heavy water moderated self-sustaining reactor that could be used to produce an atomic weapon.
Problems began to surface in the Anglo-American co-operative effort starting in mid-1942. Responsibility for the US program was being transferred to the military and security issues began to surface. The British team included a large number of escaped Europeans who had been born on now Nazi-occupied territories. This caused problems with US regulations. A second factor of concern to the USA was the large influence in the British group of representatives of ICI. ICI was seen as a commercial rival to US companies and there was reluctance by the Americans to co-operate with a company that would be a post-war rival. In August 1942 the idea was broached that perhaps Canada might therefore be a more suitable place for the heavy water based research effort.
The Montreal Laboratories
In August 1942 the British proposed to transfer to Canada a team, under the leadership von Halban, to begin work on a heavy water based research program. The proposed laboratory, which would operate within the structure of the National Research Council, led then by MacKenzie, would also enlist Canadian scientists. An agreement was then proposed whereby the British would continue to pay the salaries of their contingent while Canada assumed other costs. The agreement was approved by Clarence Decatur Howe and by late September von Halban and several others arrived in Canada.
The search then began for a suitable location for the Canadian-British effort. Montreal was chosen in late October for several reasons. One was that it would be easier to camouflage a secret operation in a larger city and thereby maintain the required secrecy. This was particularly true for the large mixed-nationality group of scientists in the British contingent who would need housing accommodations. A second reason was that the newly-built but unused medical wing of the University of Montreal could be made available for the required laboratories and offices.
Several major obstacles to a smooth co-operation with the USA began to emerge in early 1943. Stiff new regulations were being introduced by the USA regarding communications between various research groups, both within the USA and externally. The USA also placed restrictions on the transfer of information that might be of value after the end of the war. They also indicated their decision to proceed on a heavy water moderated reactor program of their own and required that any promising results obtained by the Montreal group would have to forwarded to the du Pont group who were leading the heavy water effort in the USA. The questions of security when natives of Germany, Austria, Poland and France (such as Klaus Fuchs, Alan Nunn May and Bruno Pontecorvo) were involved provided increasing concerns to the US military while the large influence of the ICI scientists provided fodder for the commercial concerns of the USA. In addition to these problems, concerns in Canada began to surface that sufficient supplies of the necessary materials, including heavy water from the Trail facility, might not be made available to the Montreal group. The USA had in place contracts for the entirety of the required materials.
The promising start of the Montreal Laboratories was put into jeopardy by the Anglo-American problems and for months it was not clear that the main group of scientists from Cambridge would in fact be transferred to Canada. Discussions came to a head in July 1943 with a historic Quebec City meeting between British Prime Minister Winston Churchill, American President Franklin Delano Roosevelt and Canadian Prime Minister William Lyon Mackenzie King. An agreement (known as “The Quebec Agreement”) was reached on the extent of the co-operation between the three countries and a Combined Policy Committee with representatives from all three countries was set up to steer the efforts. The Montreal Laboratories appeared to be back on the rails again.
All was not completely rosy within the Montreal laboratories. Information flow did not resume immediately and the supply issue of essential materials was unresolved. Furthermore, during the months of delay, domestic issues at the laboratory had arisen with the leadership of von Halban.
Co-operation between the Montreal group, which now began to grow with more scientists both from Canada and Britain, and the Chicago group slowly began to improve and the name of John Cockcroft, then at Cambridge, as a new leader for the Montreal Laboratories was proposed. However, the role that the Montreal Labs would play in the overall war effort was still unclear.
Chadwick played a leading role for the British in continuing negotiations with the Americans. In April 1944 the tri-country Combined Policy Committee reached a decision to proceed with the immediate start of the construction of a large scale, heavy water, pilot plant in Canada. Within weeks Cockcroft arrived in Canada to assume the leadership of the Montreal Laboratories.
During this extended period of uncertainty, personnel and materials had been transferred from Britain to Montreal. Between February and March 1943 key personnel and equipment arrived in Montreal including, on 14 April, the Norwegian heavy water. In addition to the imported equipment, new equipment and assistance were being procured in Canada. A 2 MV X-ray machine, the most powerful of its type then built commercially was acquired early in 1944 to act as a source of neutrons – by bombarding beryllium with X-rays. Arrangements were made with various Canadian government and university laboratories for assistance; the McMaster University group, led by Henry George “Harry” Thode for mass spectroscopic analysis and preparation of needed samples of key materials: a group at the University of Toronto, led by Fred Earl Beamish, for general chemical analysis, and the Department of Mines and Resources for a wide variety of general support.
Now that a specific purpose for the project in Canada was defined, the next urgent problem to be tackled was selecting a suitable location for the new large laboratories. The search for a suitable site has been well described by a number of authors and will not be repeated here. Suffice it to say that in July 1944 the Chalk River-Deep River area was chosen and work began immediately with the expropriation of land for the laboratories (Chalk River) and town site (Deep River). Wartime secrecy still prevailed and the location was known as the “DIL Petawawa Works” to conceal the real purpose of the project. Defence Industries Limited (DIL), a crown corporation, was chosen to project manage and build the laboratories and townsite. Construction work began in August 1944 and by late October 350 men, with suitable housing and dining accommodations were on site at Chalk River.
The first two major projects to be built at Chalk River were ZEEP (Zero Energy Experimental Pile) and NRX (National Research X-perimental, originally National Research X- metal using the code name for uranium). Design of these two facilities, complete with the appropriate services, took the highest priority at the Montreal Laboratories. To educate the large new engineering teams in the complex and unique features of these projects, a series of forty-two lectures (The Montreal Lectures) was given by the experienced members of the Montreal Laboratories during August and September of 1944.
The leader chosen for the ZEEP project was Kowarski, who had arrived in Canada in March 1945 from France via Britain with his supply of heavy water. George Klein of the NRC was the chief designer. Details of the design and construction of ZEEP are described elsewhere and it is sufficient in this short article to state simply that on 5 September 1945 ZEEP became the first reactor in the world outside the USA to go into operation. CP-1, the graphite-moderated “Chicago Pile” (and first artificial reactor) which reached criticality on 2 December 1942, had preceded it by 2 years and 9 months. CP-3, also in Chicago, was the first heavy-water moderated reactor and first reached criticality 15 May 1944 (16 months earlier than ZEEP.)
With the successful start up of ZEEP and the rapid construction of the laboratories at Chalk River, including the building that would house NRX, the transfer of personnel from the Montreal to Chalk River and Deep River began in earnest. By mid 1946 the transfer was essentially complete and the “Montreal Laboratories” were shut down.