Разделение изотопов и применение их в ядерном реакторе

The Manhattan Project was also charged with gathering intelligence on the German nuclear energy project. Through Operation Alsos, Manhattan Project personnel served in Europe, sometimes behind enemy lines, where they gathered nuclear materials and rounded up German scientists. The MED maintained control over American atomic weapons production until the formation of the United States Atomic Energy Commission in January 1947.

Contents

1 Origins

2 Feasibility

2.1 Proposals

2.2 Bomb design concepts

3 Organization

3.1 Manhattan Engineer District

3.2 Military Policy Committee

3.3 Collaboration with the United Kingdom

4 Project sites

4.1 Oak Ridge

4.2 Los Alamos

4.3 Argonne

4.4 Hanford

4.5 Canadian sites

5 Raw materials

6 Uranium

6.1 Electromagnetic separation

6.2 Gaseous diffusion

6.3 Thermal diffusion

6.4 Centrifuge

6.5 Gun-type weapon design

7 Plutonium

7.1 Reactor design

7.2 Thin Man

7.3 Separation process

7.4 Metallurgy

7.5 Implosion weapon design

7.6 Trinity

8 Foreign Intelligence

9 Bombing of Hiroshima and Nagasaki

9.1 Preparations

9.2 The use of the bombs

10 After the war

11 Cost of the Manhattan Project

 

Origins

In 1939, President Franklin Roosevelt called on Lyman Briggs of the National Bureau of Standards to head the Advisory Committee on Uranium to investigate the issues raised by the Einstein–Szilárd letter. This warned of the potential development of "extremely powerful bombs of a new type" and urged that the US should take steps to acquire stockpiles of uranium ore and accelerate research being conducted by Enrico Fermi and others into nuclear chain reactions. Briggs held a meeting on 21 October 1939 which was attended by Leo Szilárd, Edward Teller and Eugene Wigner. The committee reported to Roosevelt in November that uranium "would provide a possible source of bombs with a destructiveness vastly greater than anything now known."[1] Briggs proposed that the National Defense Research Committee (NDRC) spend $167,000 on research into the recently discovered plutonium and on uranium, particularly the uranium-235 isotope. On 28 June 1941, Roosevelt signed Executive Order 8807 which created the Office of Scientific Research and Development (OSRD), with Vannevar Bush as its director. The office was empowered to engage in large engineering projects in addition to researchThe NDRC Committee on Uranium became the S-1 Uranium Committee of the OSRD; the word "uranium" was soon dropped for security reasons.

Meanwhile, in Britain, Otto Frisch and Rudolf Peierls at the University of Birmingham made a breakthrough investigating the critical mass of uranium-235.[4] Their calculations indicated that it was within an order of magnitude of ten kilograms, which was small enough to be carried by a bomber of the day. The March 1940 Frisch–Peierls memorandum resulted in the setting up of the British Maud Committee. One of its members, the Australian physicist Marcus Oliphant, flew to the United States in late August 1941 to find out why the committee's findings were apparently being ignored. Oliphant met with the Uranium Committee and visited Berkeley, California, where he met with Ernest O. Lawrence and other physicists. Oliphant goaded the Americans into action.

At a meeting between President Roosevelt, Bush and Vice President Henry A. Wallace on 9 October 1941, the President approved the atomic program. To control it, he created a Top Policy Group consisting of himself—although he never attended a meeting—Wallace, Bush, James B. Conant, Secretary of War Henry L. Stimson and the Chief of Staff of the Army, General George C. Marshall. The Army would have principal responsibility for the project. Roosevelt also agreed to coordinate the effort with that of the British, and on 11 October he sent a message to Prime Minister Winston Churchill, suggesting that they correspond on atomic matters.

Feasibility

A 1940 meeting at Berkeley with (from left to right) Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, James B. Conant, Karl T. Compton and Alfred L. Loomis

Proposals

The S-1 Committee held its first meeting on 18 December "pervaded by an atmosphere of enthusiasm and urgency"[9] in the wake of the attack on Pearl Harbor and the subsequent declaration of war by the United States on Germany and Japan. Work was proceeding on three different techniques for isotope separation to separate uranium-235 from uranium-238. Lawrence and his team at the University of California, Berkeley investigated electromagnetic separation, while Eger Murphree and Jesse Wakefield Beams' team looked into gaseous diffusion at the Columbia University, and Philip Abelson directed research into liquid thermal diffusion at the Carnegie Institution of Washington and later the Naval Research Laboratory.[10] Murphree was also the head of the centrifuge project.

Meanwhile, there were two lines of research into nuclear reactor technology, with Harold Urey continuing research into heavy water at Columbia, while Arthur Compton brought the scientists working under his supervision at Columbia University and Princeton University to the University of Chicago, where he organized the Metallurgical Laboratory in early 1942 to study plutonium and reactors using nuclear graphite as a neutron moderator.[12] Briggs, Compton, Lawrence, Murphree and Urey met on 23 May to finalize the S-1 Committee recommendations, which called for all five technologies to be pursued. This was approved by Bush, Conant and Brigadier General Wilhelm D. Styer, the chief of staff of Major General Brehon B. Somervell's Services of Supply, who had been designated the Army's representative. They took the recommendation to the Top Policy Group with a budget proposal for $54 million for construction by the United States Army Corps of Engineers, $31 million for research and development by OSRD and $5 million for contingencies in fiscal year 1943. The Top Policy Group sent it to the President on 17 June 1942 and he approved it by writing "OK FDR" on the document.

Bomb design concepts

Compton asked the theoretical physicist J. Robert Oppenheimer of the University of California, Berkeley to take over research into fast neutron calculations—the key to calculations of critical mass and weapon detonation—from Gregory Breit, who had quit on 18 May 1942 because of concerns over lax operational security.[13] John H. Manley, a physicist at the Metallurgical Laboratory, was assigned to assist Oppenheimer by contacting and coordinating experimental physics groups scattered across the country.[14] Oppenheimer and Robert Serber of the University of Illinois examined the problems of neutron diffusion—how neutrons moved in a nuclear chain reaction—and hydrodynamics—how the explosion produced by a chain reaction might behave. To review this work and the general theory of fission reactions, Oppenheimer convened meetings at the University of Chicago in June and at the University of California, Berkeley, in July 1942 with theoretical physicists Hans Bethe, John Van Vleck, Edward Teller, Emil Konopinski, Robert Serber, Stan Frankel, and Eldred C. Nelson, the latter three former students of Oppenheimer, and experimental physicists Felix Bloch, Emilio Segrè, John Manley and Edwin McMillan. They tentatively confirmed that a fission bomb was theoretically possible.

 

Different fission bomb assembly methods explored during the July 1942 conference

 

There were still many unknown factors. The properties of pure uranium-235 were relatively unknown, as were those of plutonium, a new element which had only been discovered in February 1941 by Glenn Seaborg and his team. The scientists at the Berkeley conference envisioned creating plutonium in nuclear reactors where uranium-238 atoms absorbed neutrons which had been emitted from fissioning uranium-235 atoms. At this point no reactor had been built, and only tiny quantities of plutonium were available from cyclotrons.[16] Even by December 1943, only two milligrams had been produced. There were many ways of arranging the fissile material into a critical mass. The simplest was shooting a "cylindrical plug" into a sphere of "active material" with a "tamper"—dense material that would focus neutrons inward and keep the reacting mass together to increase its efficiency. They also explored designs involving spheroids, a primitive form of "implosion" suggested by Richard C. Tolman, and the possibility of autocatalytic methods, which would increase the efficiency of the bomb as it exploded.

Considering the idea of the fission bomb theoretically settled—at least until more experimental data was available—the Berkeley conference then turned in a different direction. Edward Teller pushed for discussion of a more powerful bomb: the "super", now usually referred to as a "hydrogen bomb", which would use the explosive force of a detonating fission bomb to ignite a nuclear fusion reaction in deuterium and tritium Teller proposed scheme after scheme, but Bethe refused each one. The fusion idea was put aside to concentrate on producing fission bombs. Teller also raised the speculative possibility that an atomic bomb might "ignite" the atmosphere because of a hypothetical fusion reaction of nitrogen nuclei. Bethe calculated that it could not happen, and a report co-authored by Teller showed that "no self-propagating chain of nuclear reactions is likely to be started." In Serber's account, Oppenheimer mentioned it to Arthur Compton, who "didn't have enough sense to shut up about it. It somehow got into a document that went to Washington" which led to the question being "never laid to rest".

Organization

Manhattan Engineer District

The Chief of Engineers, Major General Eugene Reybold selected Colonel James C. Marshall to head the Army's part of the project in June 1942. Marshall created a liaison office in Washington D.C. but established his temporary headquarters on the 18th floor of 270 Broadway in New York City, where he could draw on administrative support from the Corps of Engineers' North Atlantic Division. It was close to the Manhattan office of Stone & Webster, the principal project contractor, and to Columbia University. He had permission to draw on his former command, the Syracuse District, for staff, and he started with Lieutenant Colonel Kenneth D. Nichols, who became his deputy.

Because most of his task involved construction, Marshall worked in cooperation with the head of the Corps of Engineers Construction Division, Major General Thomas M. Robbins and his deputy, Colonel Leslie R. Groves Jr. Reybold, Somervell and Styer decided to call the project "Development of Substitute Materials", but Groves felt that this would draw attention. Since engineer districts normally carried the name of the city where they were located, Marshall and Groves agreed to instead name it the Manhattan District. This became official on 13 August, when Reybold issued the order creating the new district. Unlike other districts, it had no geographic boundaries, and Marshall had the authority of a division engineer. "Development of Substitute Materials" remained as the project codename, but was supplanted over time by "Manhattan".

Marshall later conceded that "I had never never heard of atomic fission but I did know that you could not build much of a plant, much less four of them for $90 million." A single TNT plant that Nichols had recently built in Pennsylvania had cost $128 million.[29] Nor were they impressed with estimates to the nearest order of magnitude, which Groves compared with telling a caterer to prepare for between ten and a thousand guests.[30] A survey team from Stone & Webster had already scouted a site for the production plants. The War Production Board recommended sites around Knoxville, Tennessee, an isolated area where the Tennessee Valley Authority could supply ample electric power and the rivers could provide cooling water for the reactors. After examining several sites, the survey team selected one at Oak Ridge, Tennessee. Conant advised that it be acquired at once and Styer agreed but Marshall temporized, awaiting the results of Conant's reactor experiments before taking action. Of the prospective processes, only Lawrence's electromagnetic separation appeared sufficiently advanced for construction to commence.

Marshall and Nichols began assembling the resources they would need. The first step was to obtain a high priority rating for the project. The top ratings were AA-1 through AA-4 in descending order, although there was also a special AAA rating reserved for emergencies. Ratings AA-1 and AA-2 were for essential weapons and equipment, so Colonel Lucius D. Clay, the deputy chief of staff at Services and Supply for requirements and resources, felt that the highest rating he could assign was AA-3, although he was willing to provide a AAA rating on request for critical materials if the need arose.[33] Nichols and Marshall were disappointed; AA-3 was the same priority as Nichols' TNT plant in Pennsylvania.

Military Policy Committee

J. Robert Oppenheimer and Leslie Groves at remains of the Trinity test in September 1945. The white overshoes prevent fallout from sticking to the soles of their shoes.

Bush became dissatisfied with Colonel Marshall's failure to get the project moving forward expeditiously, specifically the failure to acquire the Tennessee site, the low priority allocated to the project by the Army, and the location of his headquarters in New York City. Bush felt that more aggressive leadership was required, and spoke to Harvey Bundy and Generals Marshall, Somervell and Styer about his concerns. He wanted the project placed under a senior policy committee, with a prestigious officer, preferably Styer, as overall director.

Somervell and Styer selected Groves for the post, informing him on 17 September of this decision, and that General Marshall ordered that he be promoted to brigadier general as it was felt that the title "general" would hold more sway with the academic scientists working on the Manhattan Project.[37] Groves' orders placed him directly under Somervell rather than Reybold, with Colonel Marshall now answerable to Groves.[38] Groves established his headquarters in Washington D.C. on the fifth floor of the New War Department Building in Washington, D.C., where Colonel Marshall had his liaison office.[39] He assumed command of the Manhattan Project on 23 September. Later that day, he attended a meeting called by Stimson which established a Military Policy Committee, responsible to the Top Policy Group, consisting of Bush (with Conant as an alternate), Styer and Rear Admiral William R. Purnell.[36] Tolman and Conant were later appointed as Groves' scientific advisers.

On 19 September Groves went to Donald Nelson, the chairman of the War Production Board, and asked for broad authority to issue a AAA rating whenever it was required. Nelson initially balked but quickly caved in when Groves threatened to go to the President.[41] Groves promised not to use the AAA rating unless it was necessary. It soon transpired that for the routine requirements of the project the AAA rating was too high but the AA-3 rating was too low. After a long campaign, Groves finally received AA-1 authority on 1 July 1944.[42]

 

One of Groves' early problems was to find a director for Project Y, the group that would design and build the bomb. The obvious choice was one of the three laboratory heads, Urey, Lawrence and Compton, but they could not be spared. Compton recommended Oppenheimer, but he had two drawbacks. Unlike those three, Oppenheimer had not won a Nobel Prize, and many scientists felt that the head of such an important laboratory should have one. There were also concerns about his security status, as many of Oppenheimer's associates were communists, including his brother Frank Oppenheimer, his wife Kitty and his girlfriend Jean Tatlock. A long conversation on a train in October 1942 convinced Groves and Nichols that Oppenheimer thoroughly understood the issues involved in setting up a laboratory in a remote area and should be appointed as its director. Groves personally waived the security requirements and issued Oppenheimer a clearance on 20 July 1943.

Collaboration with the United Kingdom

The British and Americans exchanged nuclear information but did not initially pool their efforts. Britain rebuffed efforts by Bush and Conant in 1941 to strengthen cooperation with its own project, codenamed Tube Alloys.[45] However, the United Kingdom could not muster the manpower or resources of the United States, and despite its early and promising start, Tube Alloys soon fell behind its American counterpart. On 30 July 1942, Sir John Anderson, the minister responsible, advised Churchill that: "We must face the fact that ... [our] pioneering work ... is a dwindling asset and that, unless we capitalise it quickly, we shall be outstripped. We now have a real contribution to make to a 'merger.' Soon we shall have little or none."[46] By this time, the British bargaining position had worsened, and their motives were mistrusted by the Americans. Collaboration lessened markedly, and the exchange of information stopped.[47]

In August 1943 Churchill and Roosevelt negotiated the Quebec Agreement, which resulted in a resumption of cooperation.[48] The subsequent Hyde Park Agreement in September 1944 extended this cooperation to the postwar period.[49] The Quebec Agreement established the Combined Policy Committee to coordinate the efforts of the United States, United Kingdom and Canada. Stimson, Bush and Conant served as the American members of the Combined Policy Committee; Field Marshal Sir John Dill and Colonel J. J. Llewellin were the British members; and C. D. Howe was the Canadian member.[50] Llewellin returned to the United Kingdom at the end of 1943 and was replaced on the committee by Sir Ronald Ian Campbell, who in turn was replaced by the British Ambassador to the United States, Lord Halifax, in early 1945. Sir John Dill died in Washington D.C. in November 1944 and was replaced both as Chief of the British Joint Staff Mission and as a member of the Combined Policy Committee by Field Marshal Sir Henry Maitland Wilson.

James Chadwick pressed for British involvement in the Manhattan Project to the fullest extent. With Churchill's backing, he attempted to ensure that every request from Groves for assistance was honored.[52] The British Mission that arrived in the United States in December 1943 included Niels Bohr, Otto Frisch, Klaus Fuchs, Rudolf Peierls and Ernest Titterton.[53] Part of the Quebec Agreement specified that nuclear weapons would not be used against another country without mutual consent. In June 1945 Wilson agreed that the use of nuclear weapons against Japan would be recorded as a decision of the Combined Policy Committee.

The Combined Policy Committee created the Combined Development Trust in June 1944, with Groves as its chairman, to procure uranium and thorium ores on international markets. In 1944, the Combined Development Trust purchased 3,440,000 pounds (1,560,000 kg) of uranium oxide ore from companies operating mines in the Belgian Congo. In order to avoid briefing US Secretary of the Treasury Henry Morgenthau Jr. on the project, a special account not subject to the usual auditing and controls was used to hold Trust monies. Between 1944 and the time he resigned from the Trust in 1947, Groves deposited a total of $37.5 million into the Trust's account.

Project sites

A selection of U.S. sites important to the Manhattan Project. Click on the location for more information.

Oak Ridge

The day after he took over the project, Groves took a train to Tennessee with Colonel Marshall to inspect the site for the Clinton Engineer Works (CEW), the proposed production plant at Oak Ridge. Groves was suitably impressed.[56] On 29 September, United States Under Secretary of War Robert P. Patterson authorized the Corps of Engineers to compulsorily acquire 56,000 acres (23,000 ha) of land at a cost of $3.5 million. An additional 3,000 acres (1,200 ha) was subsequently acquired. About 1,000 families were affected by the condemnation order which came into effect on 7 October. Protests, legal appeals, and a 1943 congressional inquiry were to no avail. By mid-November US Marshals were tacking notices to vacate on farmhouse doors, and construction contractors were moving in. Some families were given two weeks' notice to vacate farms that had been their homes for generations; others had settled there after being evicted to make way for the Great Smoky Mountains National Park in the 1920s or the Norris Dam in the 1930s.[58] The ultimate cost of land acquisition in the area, which was not completed until March 1945, was only about $2.6 million, which worked out to around $47 an acre. When presented with Public Proclamation Number Two, which declared Oak Ridge a total exclusion zone, the Governor of Tennessee, Prentice Cooper, angrily tore it up.

The population of Oak Ridge peaked at 75,000 in May 1945, at which time 82,000 people were employed at the Clinton Engineer Works.[63] The Army presence at Oak Ridge increased in August 1943 when Nichols replaced Marshall as head of the Manhattan Engineer District. One of his first tasks was to move the district headquarters to Oak Ridge although the name of the district did not change.[64] In September 1943 the administration of community facilities was outsourced to Turner Construction Company through a subsidiary known as the Roane-Anderson Company after Anderson and Roane counties, in which Oak Ridge was located. By 1945 it employed some 10,000 people.

Los Alamos Wikisource has original text related to this article:

Los Alamos Ranch School Seizure Letter

The idea of locating Project Y at Oak Ridge was considered, but in the end it was decided to locate it in a remote location. On Oppenheimer's recommendation, the search for a suitable site was narrowed to the vicinity of Albuquerque, New Mexico, where Oppenheimer owned a ranch. In October 1942, Major John H. Dudley of the Manhattan Project was sent to survey the area, and he recommended a site near Jemez Springs, New Mexico.[66] On 16 November, Oppenheimer, Groves, Dudley and others toured the site. Oppenheimer feared that the high cliffs surrounding the site would make his people feel claustrophobic, while the engineers were concerned with the possibility of flooding. The party then moved on to the vicinity of the Los Alamos Ranch School. Oppenheimer was impressed and expressed a strong preference for the site.The engineers were concerned about the poor access road and the water supply, but otherwise felt that it was ideal.

Patterson approved the acquisition of the site on 25 November 1942, authorizing $440,000 for the purchase of the 54,000-acre (22,000 ha) site, all but 8,900 acres (3,600 ha) of which were already owned by the Federal Government. Secretary of Agriculture Claude R. Wickard authorized the War Department's use of some 46,000 acres (19,000 ha) of United States Forest Service land "so long as the military necessity continues". The need for land for a new road, and later for a right of way for a 25-mile (40 km) power line, eventually brought wartime land purchases to 45,737 acres (18,509 ha), but only $414,971 was spent.[69] Construction was contracted to the M. M. Sundt Company of Tucson, Arizona, with Willard C. Kruger and Associates of Santa Fe, New Mexico, as architect and engineer. Work commenced in December 1942. Groves initially allocated $300,000 for construction, three times Oppenheimer's estimate, with a planned completion date of 15 March 1943. It soon became clear that the scope of Project Y was greater than expected, and by the time Sundt finished in 30 November 1943, over $7 million had been spent.

Because it was secret, Los Alamos was referred to as "Site Y" or "the Hill".[71] Birth certificates of babies born in Los Alamos during the war had their place of birth listed as PO Box 1663 in Santa Fe.[72] Initially Los Alamos was to be a military laboratory with Oppenheimer and other researchers commissioned into the Army. Oppenheimer went so far as to order himself a lieutenant colonel's uniform, but two key physicists, Robert Bacher and Isidor Rabi, baulked at the idea. As a result, Conant, Groves and Oppenheimer devised a compromise whereby the laboratory was operated by the University of California under contract to the War Department.