Canada's Plutonium Contribution
to Britain's Nuclear Weapons Programme

verbatim excerpts from

Independence and Deterrence
Britain and Atomic Energy, 1945-1952

the official history of Britain's nuclear energy programme
written by Margaret Gowing (assisted by Lorna Arnold)

published by Macmillan, London, 1974

commissioned by the UK Atomic Energy Authority

Table of Contents

Britain's Atomic Bomb Policy

The Men In Charge

John Cockcroft and the Canadian Connection

William Penney and the American Connection

Christopher Hinton and the Plutonium Factories

Engineering Attitudes toward the Bomb Project

Recruiting Scientists in Montreal

Plutonium Separation Work in Canada

Plutonium from the Canadian NRX Reactor

Crisis of Confidence in Britain

Pilot Plutonium Plant in Canada Succeeds

Canadian Plutonium Sent to Britain

British Windscale Plant Begins Operations

British Nuclear Weapons Requirements

Canadian Plutonium Essential to Bomb Test

Searching for a Test Site

An A-Bomb Test Site in Canada?

Australia Volunteers

Parting Thoughts

Britain's Atomic Bomb Policy

The policy which was handed down for execution  [ by the British Government in late 1945 ]  was

These commitments were presented, at the working level, as matters of supreme importance for the British nation.

A subsidiary aim was the exploration of the potentialities of nuclear power: the shortage of fuel which bedeviled the whole economy emphasized the importance of this aim which could not, however, be achieved quickly....

... from Chapter 13: ''The Men'', page 3

The Men In Charge: Cockcroft, Penney, Hinton

Efficient execution of the atomic energy programme was regarded as essential to the nation.... In practice,  [ it ]  depended on the men running the establishments -- on two scientists and an engineer. The scientists were

The engineer was

Cockcroft and Penney had both been in the wartime atomic energy teams, although they had scarcely known each other.

... from Chapter 13: ''The Men'', pages 4-5

John Cockcroft and the Canadian Connection

Cockcroft was already well known in the world of science....

Cockcroft had thus become the natural choice for a new research establishment at Harwell....

The translation of scientific research into engineering projects had also been a feature of Cockcroft's period as director of the Canadian atomic energy project, for the famous NRX reactor  [ at Chalk River, Ontario ]  had been designed by his team and was being built by an industrial firm before Cockcroft left  [ to return to England ] ....

His greatest achievement in Canada, however, had been to turn a bitter and divided multinational group  [ the Montreal heavy water research group ]  , at a nadir of demoralisation, into a very happy, productive team, and to mend the badly torn relationships with the Canadians, who came to regard him as one of themselves....

... from Chapter 13: ''The Men'', pages 5-6

William Penney and the American Connection

Penney was the natural choice to head the research and development of atomic weapons....

When studying the effects of the bombs on Hiroshima and Nagasaki, Penney had noticed that empty petrol tins scattered about the towns were deformed to an extent clearly related to their distance from the explosion; he used this observation to good effect at the Bikini tests.... Penney decided to use several hundred Army petrol tins for recording the blast pressure at different points. When the bomb fell wide of its target, the sensitive American instruments could not record the blast properly, but with his petrol tins Penney could make a surprisingly accurate estimate of the bomb's power....

... from Chapter 13: ''The Men'', pages 6-7

Christopher Hinton and the Plutonium Factories

Hinton, unlike Cockcroft and Penney, knew nothing at all about atomic energy when he was asked at the end of 1945 to design and build the  [ plutonium production and separation ]  plants. His credentials as an engineer and as an administrator were, however, already formidable ...  [ and ]  had prepared him for the extraordinary complexities and requirements of his atomic energy post. For many years to come this new branch of engineering was to probe every weakness in an engineer's training, and Hinton's training had been as tough, thorough and wide-ranging as it could have been....

Thus in 1946, as Cockcroft, Penney and Hinton took up their posts, it seemed that the special qualities and past experience of all three had combined to produce a very rare situation: the right men all arriving in the right jobs at the right moment....

... from Chapter 13: ''The Men'', pages 7-9

However, Hinton felt that Lord Portal, his Controller, neither trusted nor supported him adequately and yet was critical if things went wrong. The tone of some of Portal's early letters to Hinton certainly had a peremptory, even nagging, tone which never appeared in letters to Cockcroft or Penney.... A note of deference to scientists can be detected which was not apparently appropriate to engineers....

... from Chapter 13: ''The Men'', page 20

Engineering Attitudes toward the Bomb Project

It seems that even though Hinton and Owen were clear that they were making fissile material for bombs, many of the staff were uncertain for some time about the purpose of their work and simply believed they were part of an industry which would produce new forms of energy. As the objects became clearer, engineers were neither attracted nor repelled by a realisation that their immediate aim was to produce the material for bombs....

... from Chapter 13: ''The Men'', page 35

Recruiting Scientists in Montreal

At the end of 1945 a two-man board from the Civil Service Commission ... visited the atomic energy teams in North America on a recruiting expedition for the Scientific Civil Service in general and for Harwell  [ the new British nuclear research establishment ]  in particular.... The board had to face the novel experience of being rejected by the interviewees, rather than the reverse, for the scientists were reluctant to go even to Harwell. Indeed no one forgot the meeting at Montreal (which Cockcroft chaired) and the storm which broke round the visitors' hapless heads.

Because of their experiences, the scientists in Canada viewed the Government service with the greatest possible suspicion and distrust.

Cockcroft told them ... that the considerable freedom of the Montreal Laboratory would continue at Harwell....

It was largely because they knew Cockcroft that so many good scientists joined the establishment. Indeed the only answer that produced complete satisfaction in Montreal was the announcement that Cockcroft was to be director of Harwell.... The scientists were devoted to him and had great faith in him.

It is fair to conclude that although other scientists might have been competent to run the research establishment, no one else (except Chadwick) would have attracted the scientists from North America who were essential to its success....

... from Chapter 13: ''The Men'', pages 25-27

Plutonium Separation Work in Canada

The Americans, during the war, had used precipitation methods for separating plutonium ... but there were all kinds of drawbacks to the large-scale use of such methods.... The section of the wartime Montreal chemistry team which was responsible for developing a plutonium separation process for the NRX pile, under its French leader, Bertrand Goldschmidt, had concentrated on a solvent extraction process because it had greater promise for the future....

The British chemistry team in Canada was asked at the end of 1946  [ by the British authorities ]  to develop by the following September a  [ plutonium ]  separation process suitable for application on an industrial scale. The team, headed by Robert Spence, consisted of twelve chemists and chemical engineers with five assistants  [ in Canada ] . The only plutonium they had for their researches was embedded in four irradiated rods which had come  [ to Montreal ]  from one of the American piles a year earlier.... The team extracted from the rods 20 milligrams of plutonium -- a quantity just about enough to cover a pinhead.... With so little knowledge of plutonium chemistry, it was extraordinarily difficult to produce the quantitative and precise data needed ... for an efficient industrial plant. However, Spence's team produced just that ...  [ and ]  precisely to time....

In the autumn of 1947 Hinton went out to Canada ...  [ and ]  went over the  [ Spence ]  report in great detail.... A continuous system of the kind contemplated was, unlike a batch system, inflexible. A very big volume of liquor would be moving through the plant, yet all parts of the plant were mutually interdependent, and if the calculations for one part were wrong the whole plant might fail. The possibility of failure was the more frightening because the plant would have to be remotely controlled from behind a thick wall of concrete and because it was believed that it would be impossible to enter it for repairs  [ due to the intense radiation fields ] ....

... from Chapter 22: ''Individual Factories'', pages 404-407

Plutonium from the Canadian NRX Reactor

The only source of plutonium for  [ further British ]  research was the NRX pile in Canada, and irradiated rods were not available there until well into 1948....

Chalk River was the site of an experimental  [ plutonium separation ]  plant which was to be fed with irradiated  [ uranium ]  slugs from the NRX pile, in order to prove the process and provide experience of radioactive operation. The confirmation most needed was about the behaviour of plutonium in the columns....

Meanwhile, the hot laboratory  [ for handling plutonium ]  at Harwell was still not finished, while difficulties with the NRX pile delayed the final active run  [ i.e. separating plutonium from highly radioactive spent fuel ]  on the Chalk River pilot plant....

... from Chapter 22: ''Individual Factories'', page 409-411

Crisis of Confidence in Britain

The crisis came in the summer of 1949.... This was Hinton's darkest hour, when everything seemed to be going wrong.... His most serious doubt was over the plant which was the most complicated of all -- the chemical separation plant at Windscale which was to ... extract the plutonium and make it into a metal....

The research and development work on which the engineers were basing their designs were being done by three sets of people: Robert Spence, with his chemical team first at Chalk River and then at Harwell, was the kingpin, while ICI chemists at Widnes and Springfields, and Harwell chemical engineers at Chalk River, were also doing vital work. Hinton feared that ... he would be unable to produce plutonium by the target date, that is, the end of March 1952....

The primary  [ plutonium ]  separation process was based on work Spence had done two years earlier in test-tubes with only milligram quantities of plutonium. It was absolutely essential to get confirmation of the process from the pilot  [ plutonium extraction ]  columns that were to operate ... at Chalk River. These were now a year late, and in any case they could only operate when sufficient highly irradiated uranium was made available by the Canadians. Overall, research information ... was six to twelve months behind Hinton's schedule. This schedule might now be unrealistic because its assumptions about the arrival of plutonium from Canada ... were unfulfilled.

"I realise", Hinton wrote, "that the urgency with which fissile material is required demands that we take risks which are quite abnormal...." Portal tried to soothe Hinton by saying that the urgency of producing atomic weapons was such that ... "even a million" spent on wide margins for unforeseen contingencies would be well spent.... This reply simply showed Hinton how little Portal understood his problems, which went far deeper than the sums of money involved.

Portal called a meeting in June 1949 with all the chief people concerned....

... from Chapter 18: ''Harwell's Role'', pages 239-241

Pilot Plutonium Plant in Canada Succeeds

News of the first active run on the Chalk River plant had arrived on the very morning of Portal's meeting, to which it was announced; although one run was not conclusive and provided only part of the information which was lacking, it suggested that in principle Spence's process would work perfectly....

In the summer of 1949, too, a part of the Harwell hot laboratories was at last ready. Hitherto it had been extremely difficult to work satisfactorily even with the traces of plutonium which were all the Harwell chemists had. Plutonium is an extremely dangerous material, so much so that more than one scientist was known to say that if he thought he had touched it with a cut finger he would immediately cut his finger off.... Nevertheless ... plutonium was not available from Canada in more than trace quantities before the laboratory was ready.

... from Chapter 18: ''Harwell's Role'', page 241

Canadian Plutonium Sent to Britain

The early research for plutonium metal production had been done with microgram quantities at Chalk River, gradually working up through milligrams to grams at Harwell.... A full-scale pilot run with Canadian plutonium was done at Harwell, and the first plutonium metal billet, bright and clean with a yield better than 98 percent, was produced there on a Saturday evening in December 1951....

... from Chapter 22: ''Individual Factories'', page 421

British Windscale Plant Begins Operations

Although the Harwell process for plutonium purification and finishing had worked very well, a process devised for operation by scientists in laboratory conditions could not necessarily be adopted in its entirety for a plant to be operated by industrial workers....

Windscale had ... no facilities for stirring and precipitating.... The plutonium fluoride which emerged ... was a dirty greenish-brown instead of the delicate pink produced by Harwell.... It was nevertheless "cooked" ...  [ and ]  when the cylinder was opened and the slug broken down, a small billet of plutonium metal was there, about the size and shape of a ten penny piece with round blobs of metal on top. It was neither very big nor very beautiful, but it was  [ metallic ]  plutonium, the end-product of six years' effort. Nor was the plutonium metal pure enough for a bomb....

The first plutonium purification and finishing plants were undoubtedly very difficult to operate in terms of safety and output. In both plants there was a constant struggle in the first months against contamination, with the staff wearing full protective clothing and masks. Courage and resolution were required....

The first, admittedly impure, billet of plutonium  [ from Windscale ]  was made on 31 March, 1952, as Hinton had promised, and Penney received the amount of plutonium to the required purity which he needed for the bomb trials....

... from Chapter 22: ''Individual Factories'', pages 421-422

British Nuclear Weapons Requirements

The decision to make an atomic bomb was taken by  [ British ]  Ministers ... at the beginning of 1947.... as a result of prompting by Dr. Penney, who had been appointed as Chief Superintendent of Armaments Research ... 1 January 1946....

Penney had hitherto played no part at all in the post-war British atomic project. He knew that preparations were being made to produce plutonium, but it is doubtful whether he knew at the outset the size of the programmed output ... the amount needed for the manufacture of 15 bombs a year....

During 1948 the Chiefs of Staff tabled their requirements for 200 bombs by 1957; there was now a firm production order for the future. Then the relentless momentum of research became apparent; having embarked on a nuclear weapon, Britain could not stop at the obsolescent Nagasaki bomb....

It was Klaus Fuchs, formerly of Los Alamos and now at Harwell, who emphasized from an early date the need for long-term work....

... from Chapter 23: ''The Weapon'', pages 442-443

When, in 1950, the date of October 1952 was fixed for the "Hurricane" trial  [ the first British A-bomb test ] , tighter planning began....

... from Chapter 23: ''The Weapon'', page 459

Canadian Plutonium Essential to Bomb Test

The plutonium metal for the core of the weapons was to be supplied by Risley, but ... Risley supplies would not be forthcoming until the spring of 1952, only six months or so before "Hurricane". Harwell was able to produce by the end of 1951 the first plutonium  [ metal ]  billet from the plutonium nitrate solutions sent from Chalk River.... From late 1951 ... metallurgists worked with the Harwell plutonium metal and with the further supplies of Canadian plutonium. Throughout 1951 they tried to do as much advance work as possible....

Only when the first Harwell billet was available at the end of 1951 was it possible to be sure that the alloy chosen  [ for the plutonium core of the bomb ]  was a practicable proposition. After the first Harwell billet  [ using Chalk River plutonium ]  had been 'knocking about' for a fortnight, it was becoming somewhat oxidised and had to be cleaned before work could begin....

... from Chapter 23: ''The Weapon'', pages 466-467

Searching for a Test Site

The need to test was implicit in the decision to make a bomb.... In terms of economy of effort and resources, there was a clear case for cooperation with the Americans.... An official request was therefore made to them  [ in November 1949 ] , but it posed difficult political and practical problems for the Americans and an official reply was long delayed.

The British decided they must consider other possibilities, while keeping their options open; in September 1950 the Chiefs of Staff recommended to the Prime Minister an Australian site suggested by the Admiralty -- the Monte Bello Islands. A message from Mr. Atlee was soon handed to Mr. Menzies, the Australian Prime Minister....

... from Chapter 24: ''Monte Bello'', page 476

An A-Bomb Test Site in Canada?

Meanwhile, Penney had been in Canada looking for  [ bomb test ]  sites; this visit, arranged with Dr. Solandt (chairman of the Canadian Defence Research Board) was a feasibility study only.... Penney was seeking more than a site for the first test, and the joint report which he and his Canadian colleagues produced looked forward for some years.

It defined three types of trials:

  1. to test the functioning of a weapon;

  2. given a weapon of known power, to discover certain physical effects (for instance, the effect of an explosion in shallow water); and

  3. to prove the functioning and ballistics of an operational weapon.

If a tripartite agreement were reached on a common proving ground in Canada, the report continued, there might be one or two trials a year for several years; the site would have to be generously staffed and equipped with instruments. Assuming complete Anglo-Canadian integration but no tripartite agreement, the staff required for the first trial would be 200 scientists, 50 technicians and 100 industrial workers. Most of the scientists would be provided by Britain, with help from the Canadians in chemical analysis and radiological safety, and most of the industrial workers by Canada; Canada would undertake the construction work; costs would be shared on an agreed basis.

If the first British test were to be a ground burst, the  [ Canadian ]  site would have to be ready by the summer of 1952. It might, however, be an explosion in a ship, since one "base surge" trial seemed necessary to investigate the effects of an explosion in shallow water, such as a ship-borne atomic bomb might produce in a major port.... Failing a suitable site  [ for such a ship-board test ]  in Canada, it would have to be carried out by means of an expedition in the Pacific; a Canadian  [ land-based ]  site would then be used only for subsequent trials and would not have to be ready until the summer of 1953.

The report set out the requirements for a site: a detonation area; a temporary camp at least 10 miles upwind; a base camp, with laboratories, workshops and signals office, at least 25 miles away upwind. It would have to be isolated, with no human habitation within 100 miles downwind in a wide sector; prevailing winds should blow contamination over the sea but clear of shipping. It should be large enough to accommodate the detonation of about a dozen weapons over several years; since each explosion would cause severe contamination over an area of about 500 yards radius which could not be used again, each detonation would have to be at least 3 miles from the previous trial. Of the seven Canadian sites investigated, one near Churchill, Manitoba, on the west coast of Hudson Bay, seemed ideal, except that the sea was too shallow for ships to be used near the shore....

... from Chapter 24: ''Monte Bello'', pages 477-478

Australia Volunteers

The Australian Government formally agreed  [ to the use of the Monte Bello Islands ]  in May 1951 and provisional preparations began....

... from Chapter 24: ''Monte Bello'', page 479

The Monte Bello bomb was terrifyingly real and could be measured in terms of blast and radioactivity by the monitoring machines spread about the islands. Yet it was also curiously unreal. The initial product of the huge industrial effort was just two lumps of an ordinary-looking heavy grey metal  [ plutonium ] , no more than one man could carry by hand on the journey to Monte Bello. One of these lumps, encapsulated in its shapes of high explosive, had produced, in a microsecond of activity, a soaring plume and mushroom cloud laden with lethal contents, and a blast equal to that of 20,000 tons of TNT.

The whole and acknowledged point of the bomb and its successors was that they should not be used except in tests. If they were used, they had failed in their purpose, which was deterrence. If two sides used them in warfare, any victory was bound to be pyrrhic....

... from Chapter 25: ''Epilogue'', page 497

Parting Thoughts

Because of the discovery of atomic energy, radioactive materials which had lain useless but harmless in the earth had been extracted and concentrated into effective but dangerous forms, and were becoming widely used. A new element of devastating power and fearful toxicity -- plutonium -- which did not exist on earth (except perhaps in minute traces) was being created in quantity; as plutonium-239, with a half-life of 24,000 years, it would remain active and dangerous for millennia, since there were no means of rendering it harmless. The plants where the reactor fuel rods were processed were potentially very hazardous.... The really massive increase in radioactive material on the earth's surface was taking place in the nuclear reactors themselves, where the contained fission products and induced radioactivity were enormous in quantity.

Such novel threats to the health and safety of workers and the population, so little understood by politicians or the public, imposed a heavy responsibility on the scientists and engineers. They were remarkably successful in coping with the problems in this  [ early ]  period.... Could the cautious confidence induced by success so far be projected into an era of a large-scale nuclear power programme and its multiplied hazards? This question goes beyond the scope of the present volume.

... from Chapter 25: ''Epilogue'', page 503

"Pile" is a British term for "nuclear reactor" -- used especially in the early years.

[ Canadian role in various Bomb programs ]

 [ Canada's Nuclear History ]


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