For Canada, it really began in February 1940, a few months after the start of the Second World War, the day the French Prime Minister Edouard Daladier gave his consent to the dispatch to Norway of a French secret agent to acquire the worldwide stock of heavy water, a paramount decision in the race toward the chain reaction started a year earlier following the discovery of fission. This discovery had been itself the result of an extraordinary case of scientific collaboration and competition between the main European laboratories prying into the secret of the matter.
First took place two major discoveries: the neutron by James Chadwick in 1932 at the Cavendish Laboratory in Cambridge, then artificial radioactivity in 1934 by Frederic Joliot and his wife Irène Curie (the daughter of the famous Curie couple) at the Radium Institute in Paris. Soon afterwards Enrico Fermi and his team in Rome found that neutrons were the most efficient particles to produce artificial radioisotopes, still more when slowed down, and they then started the study of the complex mixture of radioactive products obtained by neutron bombardment of uranium. From 1935 to 1938, Otto Hahn, Lise Meitner and Fritz Strassmann at the Kaiser Wilhelm Institute in Berlin investigated thoroughly the problem and were convinced that they had successfully identified the many supposed transuranium radioelements formed in the reaction. However in 1937 and 1938 Irène Curie and the Yugoslav scientist Pavel Savic, once again in Paris, questioned and disproved the Berlin team's result without finding themselves the solution but putting at last the Germans on the right track. Thus at the end of December 1938 Hahn and Strassmann gave the chemical clue to the enigma leading a few days later to the physical explanation of fission by Lise Meitner, now a refugee in Sweden, and her nephew Otto Frisch who himself gave the crucial experimental proof in early January 1939 at the Niels Bohr Institute in Copenhagen.
The race for the chain reaction was definitely on when in March 1939, at one week's distance, the two future competing teams in that race - Joliot and his collaborators Hans von Halban and Lew Kowarski at the Collège de France, and Enrico Fermi and Leo Szilard at Columbia University - showed that neutrons were liberated during the fission of uranium.
In April the French announced that they evaluated the number of neutrons liberated by fission to be 3.5 ± 0.7 (it is in reality 2.5). By then Joliot, Halban and Kowarski, who had been joined by the theoretical physicist Francis Perrin, felt they had a rather clear picture of the outline of both a future energy producing machine as well as an explosive device, and decided to patent the features of such a machine and device if only to have a protection in France against patents taken in another country.
Three patents were thus registered in secret between May 1 and May 4 in the name of the Caisse Nationale de la Recherche Scientifique, the main financial backer of the Collège de France research. The four inventors intended to keep only 5% each of the benefits with the remaining 80% going to help scientific research. These patents were the first ever to be taken out on the chain reaction in uranium.
The first two patents concerned energy production and were entitled "Device for energy production" and "Method for stabilizing a device for energy production". They roughly defined the principles of the main components of our present power reactors: moderator in heterogeneous or homogeneous arrangements, cooling fluid, control rods, protection shield. The third patent called "Method for perfecting explosive charges" was less brilliant from a foresight point of view though it proposed valid solutions for the trigger, the tamper and the rapid obtainment of the critical assembly of a possible explosive device. Finally, nearly a year later, after Alfred Nier's experimental confirmation in March 1940 of Niels Bohr's theoretical prediction that uranium-235, the rare isotope of the mixture in natural uranium, was responsible for fission by slow neutrons, the French took out in April 1940 an additional patent on the advantage of using enriched uranium for the chain reaction.
In May 1939, immediately after the taking out of the first patents Joliot decided to deal with the question of uranium procurement, and on May 8 met in Brussels with the leaders of the mining firm Union Minière du Haut-Katanga to explain to them the new importance of uranium, a mainly unused residue of the production of radium of which they were the main world supplier. Thanks to the richest known ore deposit in the Belgian Congo (65% in uranium oxide) the Belgian firm had enjoyed a world monopoly for the production of radium (one gram of which is present for every three tons of uranium) from the mid-twenties to the mid-thirties, and had shared it since the mid-thirties with the Canadian firm Eldorado Gold Mining which exploited an important but less rich deposit discovered in 1930 at Great Bear Lake. A 60%-40% cartel had even been formed in 1938 between the two firms to maintain the price of radium at $25,000 a gram, while the pound of uranium oxide was worth one dollar. Today, thanks to uranium fission, radium has been totally dethroned for medical uses by cobalt-60, which, in a form about 100 to 200 times more concentrated, is sold at a price of about a dollar for the amount equivalent to one gram of radium.
On May 10, Edgar Sengier the chair man of Union Minière, consulted in London with Henry Tizard, principal scientific adviser of the British Government, who was then rather doubtful about the practical future of uranium fission. On May 13 Sengier came to Paris and agreed to set up an exclusive joint venture between his firm and the CNRS, the rightful holder of the patents for the future exploitation of the patents. An agreement was drafted and initialed the same day, but was never concluded because of the advent of the war a few months later and also the delays linked to the complications in setting up a joint enterprise between a French Government agency and a foreign industrial firm.
The agreement stipulated that a Franco-Belgian syndicate would be responsible for the world exploitation of the French patents and would be set up after the successful outcome of two experiments. The first, with five tons of uranium oxide, the second with fifty tons, were to be supplied by Union Minière. A first consignment of five tons was sent to Paris immediately in June 1939 and later, in April 1940, three more tons were sent before the German invasion. This early procurement by Joliot of eight tons of uranium shows clearly the advance taken at that stage by the College de France team on the Columbia University one, as Fermi and Szilard were not able to get hold of their first few tons of uranium oxide before the second half of 1941. These eight tons of uranium oxide were hidden in Morocco during the five years of the German occupation of France and turned out to be an indispensable asset for the start up of the French Commissariat à l'Energie Atomique for fueling its first two low power experimental piles at a time when all the uranium resources available in the Western world had been cornered by the Anglo-American supply agency created following the 1943 Quebec Summit Conference and agreement for atomic collaboration.
The importance of the Franco-Belgian discussions was acknowledged in 1957 in a letter from Sengier to Halban: "Needless to say, these conversations impressed me very much, and drew my most serious attention to the importance of uranium as a potential material for bombs, and the danger of uranium ores falling into the hands of a possible enemy.... That is the reason why I shipped from Africa to America, a stock of rich ore and placed it at the disposal of our Allies".
During the summer and fall of 1939, while the war started in Europe, the French team gave its attention to the choice of a moderator. Their experimental results led them to the conclusion that it was almost impossible to obtain a sustained chain reaction with hydrogen and natural uranium and doubtful that such a reaction could take place in a carbon moderated system. Deuterium in heavy water seemed by far the best moderator.
At the beginning of the war Joliot had obtained full support from Raoul Dautry, the Minister of Armaments, responsible also for the CNRS, for the production of an energy generator as a first step towards a possible submarine engine. As he had convinced the leaders of Union Minière six months earlier, he had easily convinced his minister who did not feel it necessary to seek the opinion of other scientists or, as was the case in England and the United States, to create an official committee for evaluating and supervising the uranium project.
In a report submitted to Dautry at the end of 1939, Joliot specified: "a properly constituted mixture of uranium and heavy water, at this present stage of our knowledge, has all the conditions favorable for the realization of a chain reaction, and consequently for a massive release of energy".
At that time heavy water, discovered in 1932 by the American chemist Harold Urey, worth about half a dollar a gram, had no other uses than research. Nevertheless a Norwegian enterprise, Norsk Hydro, whose majority stock was in the hands of French holders, had begun a small scale production by fractional electrolysis profiting from the low cost of electricity. By 1940, a total of about 200 kilograms had been separated. Joliot suggested to Dautry to try to get a loan of this entire stock valued at $120,000,specifying in his report that: "if our experiments are successful, that is, if we achieve a massive release of energy, even though our materials are likely to be destroyed, the loss would be negligible compared with the industrial consequences of such a success. If we fail then all the materials will be completely recoverable".
News from Norway, that the German firm I G Farben was also interested in buying this stock and all future increased production, hastened the departure of a French secret mission under the direction of Jacques Allier, an engineer and banker who was already in contact with Norsk Hydro. His mission, approved by Edouard Daladier, the prime minister, and helped by French military intelligence agents was a complete success. The whole available stock of 185 kilograms was loaned to France for the duration of the hostilities. In addition Norsk Hydro undertook to accelerate future production, all of which would be reserved for France. The mission was back in Paris, with 26 precious cans, on March 9, 1940, exactly one month before the German invasion of Norway.
During this vital mission, French military intelligence, insisting on absolute secrecy, had expressed concern about the original nationality, Austrian and Russian, of Joliot's two main coworkers Halban and Kowarski who were only naturalized French in 1939. To guarantee, in case there was a security leak, that neither could be suspected, Joliot asked each of them to spend the duration of the mission under surveillance. Their compulsory holidays in two islands, one in the Mediterranean, the other in Brittany, ended with the arrival of the heavy water in the cellars of the College de France. From being security risks, Halban and Kowarski became once again indispensable scientists.
The two following months were devoted to setting up the decisive experiment but, in spite of strenuous efforts, this was still not ready when the German advance started to engulf the country. When all hope of stopping this advance was lost, Dautry ordered Joliot, Halban and Kowarski to go to Bordeaux and then to England. Joliot however decided not to abandon his laboratory, where the first European cyclotron was under construction, but on June 18th, Halban, Kowarski and the 26 cans of heavy water boarded a coal-carrying vessel for England. Their mission order read: "They are required to continue in England, in absolute secrecy, the research begun at the College de France". So three months after being under a form of house arrest during the heavy water purchase in Norway, Halban and Kowarski found themselves charged with the great responsibility of trying to preserve France's position, initially so promising, in the atomic race.
Halban and Kowarski, their heavy water and their project were well received in England by their scientific colleagues - in particular by James Chadwick and John Cockcroft - with an interest that was all the greater because so far the British had turned their attention towards the uranium-235 bomb, following a March 1940 memorandum by Otto Frisch and Rudolph Peierls, and had given little thought to the recovery of useful energy.
The coordinating British committee, code-named the Maud Committee, invited the two French refugee scientists to stay in England and continue their research at the Cavendish Laboratory in Cambridge. In mid-December they were ready to proceed with the crucial experiment planned in Paris. It consisted of the measurement of the neutron density distribution curves inside and outside a 60 cm diameter aluminium sphere rotating at 20 revolutions per minute so as to maintain in homogeneous suspension fine uranium oxide powder in the heavy water. A neutron source of 1 gram of radium-beryllium was situated in the center of the sphere which was placed in a tank full of mineral oil so as to recover the heavy water in case of accident. The neutron flux emitted from the sphere was more intense in the presence of uranium oxide in the sphere, and the increase of flux was sufficiently large for the experimenters to be able to affirm, with reasonable certainty, that with much more heavy water and uranium a chain reaction was indeed possible.
|Some of the initial research staff of the Montreal Laboratory, 1943 with the Canadians having (C) after
Standing: A.M. Munn (C), B. Goldschmidt, J.W. Ozeroff (C), B.W. Sargent (C), G.A. Graham (C), J. Gueron, H.F. Freundlich, H.H. Halban, R.E. Newell, F.R. Jackson, J.D. Cockcroft (visiting the Laboratory), P. Auger, S.G. Bauer, N.Q. Lawrence, A. Nunn May.
Seated: W.J. Knowles (C), P. Demers (C), J.R. Leicester, H. Seligman, E.D. Courant, E.P. Hincks (C), F.W. Penning, G.C. Laurence (C), B. Pontecorvo, G.M. Volkoff (C), A. Weinberg (U.S. Liaison Officer), G. Placzek.
|A young Bertrand Goldschmidt.|
|Lew Kowalski (left) with Frederik Joliot and Hans von Halban.|
Exactly two years after the discovery of Hahn and Strassmann, and six months after leaving France, Halban and Kowarski were the first to demonstrate that it would be possible to produce atomic energy starting with natural uranium. As the report of the Maud Committee of June 1941 stated: "Their results showed a definite indication of a divergent chain process; for each initial neutron, 1.06 ± 0.02 were produced in one set of experiments, 1.05 ± 0.015 in another set. The system used was relatively small owing to the fact that the amount of heavy water at their disposal was only 180 kilograms and a large loss of neutrons from the surface prevented a divergent chain from developing. They estimate that the critical size of the system which would liberate large amounts of energy would require 3 to 6 tons of heavy water ...".
The world supply of heavy water had kept its promise and yielded its secret. The full-scale experiment would require fifteen to thirty times more and this was proved exact by the two first natural uranium heavy water piles built and which diverged in the USA at Argonne in May 1944 and in Canada at Chalk River in September 1945.
The Maud Committee concluded that "Drs. Halban and Kowarski have done all they can with the supplies which they brought to this country", and advised "that they should be allowed to work in the U.S." where steps were being taken to produce heavy water industrially mainly on the basis of the favorable results of their experiments. Furthermore Glenn Seaborg, working at the University of Berkeley and utilizing its cyclotron, found that uranium 238 gives, by neutron bombardment a long lived isotope of element 94. This plutonium 239 has the same fissile properties as that of uranium-235. It would be produced in a "machine of the Halban type" which could therefore be used for military purposes.
During the fall of 1941, the whole atomic effort in Great Britain was reorganized under the Department of Scientific and Industrial Research (DSIR) and given the code name of Tube Alloys. Wallace Akers, the Research Director of Imperial Chemical Industries (ICI) was to become its director and the Lord President, Sir John Anderson, the minister in charge. Halban was to be responsible for the work on the chain reaction by slow neutrons.
In early 1942, Akers led a mission to the USA of the main leaders of Tube Alloys. Halban was hoping to convince the Americans to host his Cambridge team as an independent British unit at or near the University of Chicago where all the American work had just been concentrated under the code name of Metallurgical Laboratory and under the leadership of Arthur Compton. This project, soon to comprise more than a hundred scientists, was going ahead at full speed in two main directions: the graphite uranium system developed by Fermi and his team, and the plutonium isolation and extraction problem by Seaborg's team.
At that time the Cambridge group comprised only ten researchers: five of German and Austrian origin, three Frenchmen (Jules Gueron, a physical chemist had recently joined Halban and Kowarski) and only two English scientists. Washington, absolutely opposed to their settling in the U.S. as an independent British unit, offered Halban a position in the Chicago group as responsible for the heavy water work, assisted perhaps by either Kowarski or Gueron but only if an equivalent scientist could not be found in the U.S.
Halban refused to sever his British links. He wanted to lead his own team and still had hopes to be the first to achieve a sustained chain reaction. He convinced the British authorities that their position was strong thanks to the Cambridge work and future rights on the French patents. In exchange for the help received in England, he had undertaken to obtain from the French after the war a transfer to the British government of the rights, outside France and the French empire, of the initial French patents considered by him as master patents for any future industrial development.
He then proposed, with the approval of Washington, that his team should be transferred to Canada as the nucleus of a much larger Anglo-Canadian outfit. Churchill agreed and the final decision to launch such an enterprise was taken in London on October 12, 1942, at a meeting between Anderson and Clarence Decatur Howe the Canadian Minister of Munitions and Supply. C.D. Howe and Dean Jack Mackenzie, acting President of the National Research Council (NRC), were to be during the war the two Canadians responsible for this first scientific multinational project ever created. Its international character was reinforced by the French nationality of Halban, its first director, and the European origin of several of its division and section leaders. Furthermore, it was to be dependent on the U.S. for technical help and basic materials such as heavy water and pure uranium metal.
Final arrangements, and the decision to locate the laboratory in Montreal, were the results of a meeting on October 30 in Ottawa where I had just been summoned by Halban and where I visited with great interest the graphite uranium experiment undertaken at the NRC by George Laurence. I was a specialist in radio chemistry, having been recruited by Marie Curie at the Radium Institute in 1933, the year before her death. Having joined the Free French Forces in the States in early 1942, I had been seconded to the DSIR which had sent me to Chicago during the summer of 1942 where I participated, under Seaborg, in the identification of some of the main long-lived fission products as well as to the isolation of the first quarter of a milligram of plutonium. I was now to be a section leader with the Montreal project in the chemistry division under Fritz Paneth, a renowned Austrian radiochemist.
Thereafter several weeks were spent in Montreal looking in vain for a suitable location for the laboratory, until my chance encounter with a French refugee biologist, professor at the Université de Montréal, Henri Laugier, the former director of the CNRS, who as such had been involved in the taking out of the French patents. He suggested to me the unoccupied wings of the University which, because of lack of funds, had not yet been equipped for the medical school. This was to be an unexpected French contribution to the new project.
Agreement by Halban, Ottawa and the University followed and the plans for the new laboratory were expeditiously prepared by Ernest Cormier, the architect of the University. The premises were ready for occupancy in March 1943 when the Cambridge team and many newly recruited British technicians, scientists and engineers reached the calm side of the Atlantic.
Kowarski was not to be among the pioneers of the Montreal laboratory. His personal relations with Halban had deteriorated with the passing of time and the politicization of the venture, and another French refugee physicist of worldwide repute, Pierre Auger, had accepted the direction of the physics division of the project.
A far greater turbulence was going to rock the Anglo-Canadian outfit before it had taken off. On December 2nd, 1942, the first self-sustaining chain reaction had taken place in the pile of uranium and graphite Fermi built in Chicago. Three weeks later, Roosevelt, briefed on the great technical advance of the American project, recently put under army responsibility and control, decided to limit drastically the exchanges with the British, a first American move on the road to non-proliferation. The allocation of the first tons of heavy water produced in the U.S. and, with complete American funding, at Trail, B.C. was to be decided at a later date, meanwhile the Montreal laboratory would have to limit itself to fundamental research on the utilization of heavy water. In a way, the future Anglo-Canadian team was being asked to furnish its gray matter to the American scientists and industry in case they should decide to build a first heavy water pile.
The breakdown in relations became complete in March, but not before a last minute successful "spying" mission to Chicago by Auger and myself, in early February, where we obtained from our American colleagues the most recent technical information on Fermi's pile and on plutonium extraction, as well as four micrograms of plutonium and a sample of long-lived fission products from the material I had dealt with in Seaborg's laboratory.
For the team just settled in Montreal, and expecting to profit from being at an easy distance from Chicago's Metallurgical Laboratory and many of the American resources, Roosevelt's decision was a terrible blow. It was further amplified when it was learned that, unknown to the British, the Canadians had sold out in advance to the American project all their uranium production until 1946. The roughly one hundred technicians and scientists of the Anglo-Canadian team were thus denied access to uranium, heavy water, plutonium and American help and so found themselves condemned to inaction almost before they had begun to work. Their demoralization was to be further increased by the difficult character, the authoritarian manners and the poor managerial abilities of Halban, their leader.
Fortunately Churchill, who did not know that Roosevelt himself had been responsible for the break, fought back and, at each summit meeting with him in 1943 (Casablanca in February, Washington in May, and Quebec in August) insisted that collaboration should be complete in this field as in all others independently of the ratio of the contributions of the two Allies. Roosevelt agreed each time but without giving instructions to lower levels. He could not keep up this double attitude for long however and agreed at Quebec that collaboration should be resumed. However it was specified in the Quebec Agreement that, in the industrial field, exchange of information should be limited to what was necessary for the pursuit of the war. Churchill agreed on this clause to counter the American accusations that the British were overly interested in patent rights and postwar commercial benefits since they had given ICI an excessive part in running Tube Alloys.
The renewal of this somewhat limited collaboration was helped by the British decision to send Chadwick to Washington to maintain liaison with the American project and its head General Leslie Groves. Early in January 1944, a meeting presided over by these two leaders took place in Chicago to re-establish the links between the Metallurgical and Montreal Laboratories. The meeting was inconclusive and marked by dissension as Groves insisted that plutonium chemistry and extraction technology were to be excluded from a renewed collaboration.
Furthermore it was revealed that a first heavy water pile was under construction at Argonne, Illinois and divergence due to be achieved in a few months (it diverged in May 1944). This task had been given by Compton to the Chicago pioneers of the first graphite pile when they had been deprived of the responsibility of planning and building the large graphite-producing piles which had been transferred, in mid-1943, to the private industrial firm DuPont. So the "raison d'etre" of the Anglo-Canadian project had been, unknown to Montreal, entrusted to the Chicago scientists like a toy to soothe their frustration. It was only then that Halban realized that, contrary to his hopes since 1940, he would not be the first to obtain the heavy water chain reaction. He was to be replaced in May 1944 by the British physicist John Cockcroft as head of the Laboratory and was to leave atomic energy one year later after a political drama caused by an untimely visit by him to Joliot in Paris after the Liberation to discuss the patent rights problems. This visit had been authorized by Anderson but vetoed by Washington.
After the January 1944 Chicago meeting, Chadwick continued to try to reverse the American opposition to the building of a large heavy water reactor in Canada. In February, Groves, Mackenzie and he entrusted to Major Arthur Peterson, Groves' representative in Chicago, a study on the question. It came again to a negative conclusion because a Canadian pile would be of no help in winning the war. However this report emphasized the qualities of heavy water piles: "the advantage of heavy water piles may be so marked, and their post-war applications may be so important and far reaching, that their development cannot be wholly neglected".
Chadwick was in Los Alamos, the secret bomb centre in New Mexico, when he got the report. Groves joined him on March 27th still opposed to the Canadian pile. At the end of the day Chadwick succeeded in getting him to change his mind, abandoning the idea of a pile whose plutonium production could have had a real military importance, and accepting instead a ten thousand kilowatt one, thirty times greater than the first one which was about to be completed in Chicago.
It was on that evening that Halban and Kowarski's mission finally took shape. After the long and disappointing delays, the Montreal Group was to build an industrial-size pile, the future NRX, a genuine step toward atomic energy. Halban's main objective was achieved but by an irony of fate, he was not going to bring it to fruition. Rather it was to be Chadwick and Cockcroft, the very scientists who had received him and Kowarski so cordially upon their arrival in England nearly three years earlier.
However, in July 1944, Cockcroft took the wise decision to tackle first a much smaller unit of near zero power and entrusted its construction to Kowarski whom he had called back from Cambridge. It was to be ZEEP which diverged at Chalk River on September 5, 1945. Justice had been done. One of the members of the French nuclear "tandem" had the honour of building, if not the first heavy water pile in the world, at least the first atomic pile outside the United States.
Chadwick succeeded also in partially solving the plutonium problem. Renouncing "until further notice" any American know-how on the new element, he obtained, at a meeting in Chicago on June 8, 1944 (two days after the Normandy landings) with Groves, Cockcroft and Mackenzie, the American promise of a few irradiated uranium rods from the second American pile (the Oak Ridge one). These contained a few milligrams of plutonium and enabled the Montreal group to work out independently extraction and chemical properties of the new element.
Taking advantage of my experience with Seaborg's group in 1942, I was able, with a small team of Canadian chemists, to establish the outline of the first solvent extraction process for plutonium in 1945, thus demonstrating for the first time the relative ineffectiveness of the policy of secrecy in such a specifically sensitive field as the reprocessing of irradiated fuels and paradoxically between close allies during the war. The so-called Trigly process led to the production, in Chalk River in the late forties and early fifties, of about fifteen kilograms of plutonium which would probably have allowed Canada, had it not been the first country to freely renounce the bomb, to be the third military nuclear nation in addition to becoming the world champion of heavy water power reactors.
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