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14 January 2019

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DuPont recommended that the site be located far from the existing uranium production facility at Oak Ridge. There are many different flavours of Kit Kat, including milk, white, and dark chocolate.

Отмена операции осуществляется до проведения Банком процедуры закрытия дня до 23:59 часов Московского времени дня совершения операции в соответствии с «Руководством по использованию аппаратно-программного комплекса электронной коммерции». For other uses, see. In Ireland, France, the UK and America Nestlé also produces a Kit Kat , and in Australia and Malaysia, Kit Kat. As it can be seen from the EVLKSTCOMET10-1 picture, a special effort has been made to create the development kit compact and optimized to fit the size of a real meter.

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This article is about the atomic bomb project. For other uses, see. The Manhattan Project was a research and development undertaking during that produced the first. It was led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946, the project was under the direction of of the. Nuclear physicist was the director of the that designed the actual bombs. The Army component of the project was designated the Manhattan District; gradually superseded the official codename, Development of Substitute Materials, for the entire project. Along the way, the project absorbed its earlier British counterpart,. Over 90% of the cost was for building factories and to produce , with less than 10% for development and production of the weapons. Research and production took place at more than 30 sites across the United States, the United Kingdom, and Canada. Manhattan District Two types of atomic bombs were developed concurrently during the war: a relatively simple and a more complex. The gun-type design proved impractical to use with , and therefore a simpler gun-type called was developed that used , an that makes up only 0. Chemically identical to the most common isotope, , and with almost the same mass, it proved difficult to separate the two. Three methods were employed for : , and. Most of this work was performed at the at. In parallel with the work on uranium was an effort to produce plutonium. After the feasibility of the world's was demonstrated in Chicago at the , it designed the at Oak Ridge and the production reactors in , in which uranium was irradiated and into plutonium. The plutonium was then chemically separated from the uranium, using the. The plutonium implosion-type weapon was developed in a concerted design and development effort by the Los Alamos Laboratory. The project was also charged with gathering intelligence on the. Through , Manhattan Project personnel served in Europe, sometimes behind enemy lines, where they gathered nuclear materials and documents, and rounded up German scientists. Despite the Manhattan Project's tight security, Soviet successfully penetrated the program. The first nuclear device ever detonated was an implosion-type bomb at the , conducted at New Mexico's on 16 July 1945. Little Boy and Fat Man bombs were used a month later in the , respectively. In the immediate postwar years, the Manhattan Project conducted weapons testing at as part of , developed new weapons, promoted the development of the network of , supported medical research into and laid the foundations for the. It maintained control over American atomic weapons research and production until the formation of the in January 1947. The discovery of by German chemists and in 1938, and its theoretical explanation by and , made the development of an a theoretical possibility. There were fears that a would develop one first, especially among scientists who were refugees from and other countries. It urged the United States to take steps to acquire stockpiles of and accelerate the research of and others into. They had it signed by and delivered to. Roosevelt called on of the to head the to investigate the issues raised by the letter. Briggs held a meeting on 21 October 1939, which was attended by Szilárd, Wigner and. On 28 June 1941, Roosevelt signed Executive Order 8807, which created the OSRD , with as its director. The office was empowered to engage in large engineering projects in addition to research. In Britain, Frisch and at the had made a breakthrough investigating the of uranium-235 in June 1939. Their calculations indicated that it was within an of 10 kilograms 22 lb , which was small enough to be carried by a bomber of the day. Their March 1940 initiated the British atomic bomb project and its , which unanimously recommended pursuing the development of an atomic bomb. In July 1940, Britain had offered to give the United States access to its scientific research, and the 's briefed American scientists on British developments. He discovered that the American project was smaller than the British, and not as far advanced. As part of the scientific exchange, the Maud Committee's findings were conveyed to the United States. One of its members, the Australian physicist , flew to the United States in late August 1941 and discovered that data provided by the Maud Committee had not reached key American physicists. Oliphant then set out to find out why the committee's findings were apparently being ignored. He met with the Uranium Committee and visited , where he spoke persuasively to. Lawrence was sufficiently impressed to commence his own research into uranium. He in turn spoke to , and. Oliphant's mission was therefore a success; key American physicists were now aware of the potential power of an atomic bomb. On 9 October 1941, President Roosevelt approved the atomic program after he convened a meeting with Vannevar Bush and Vice President. To control the program, he created a Top Policy Group consisting of himself—although he never attended a meeting—Wallace, Bush, Conant, , and the ,. Roosevelt chose the Army to run the project rather than the Navy, because the Army had more experience with management of large-scale construction projects. He also agreed to coordinate the effort with that of the British, and on 11 October he sent a message to Prime Minister , suggesting that they correspond on atomic matters. Work was proceeding on three different techniques for to separate uranium-235 from the more abundant. Lawrence and his team at the , investigated , while and 's team looked into at , and directed research into at the and later the. Murphree was also the head of an unsuccessful separation project using. Meanwhile, there were two lines of research into , with continuing research into at Columbia, while Arthur Compton brought the scientists working under his supervision from Columbia, California and to join his team at the , where he organized the in early 1942 to study plutonium and reactors using as a. Briggs, Compton, Lawrence, Murphree, and Urey met on 23 May 1942 to finalize the S-1 Committee recommendations, which called for all five technologies to be pursued. This was approved by Bush, Conant, and , the chief of staff of 's , who had been designated the Army's representative on nuclear matters. Bomb design concepts Different fission bomb assembly methods explored during the July 1942 conference Compton asked theoretical physicist of the University of California, Berkeley, to take over research into —the key to calculations of critical mass and weapon detonation—from , who had quit on 18 May 1942 because of concerns over lax operational security. Oppenheimer and of the examined the problems of diffusion—how neutrons moved in a nuclear chain reaction—and —how the explosion produced by a chain reaction might behave. To review this work and the general theory of fission reactions, Oppenheimer and convened meetings at the University of Chicago in June and at the University of California, Berkeley, in July 1942 with theoretical physicists , , Edward Teller, , Robert Serber, , and Eldred C. Nelson, the latter three former students of Oppenheimer, and , , , , and. They tentatively confirmed that a fission bomb was theoretically possible. There were still many unknown factors. The properties of pure uranium-235 were relatively unknown, as were those of plutonium, an element that had only been discovered in February 1941 by and his team. The scientists at the Berkeley conference envisioned creating plutonium in nuclear reactors where uranium-238 atoms absorbed neutrons that 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. Even by December 1943, only two had been produced. There were many ways of arranging the fissile material into a critical mass. 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. Teller proposed scheme after scheme, but Bethe refused each one. The fusion idea was put aside to concentrate on producing fission bombs. Manhattan District The , Major General , selected to head the Army's part of the project in June 1942. Marshall created a liaison office in Washington, D. It was close to the Manhattan office of , 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 , who became his deputy. Manhattan Project Organization Chart, 1 May 1946 Because most of his task involved construction, Marshall worked in cooperation with the head of the Corps of Engineers Construction Division, Major General , and his deputy, Colonel. Since engineer districts normally carried the name of the city where they were located, Marshall and Groves agreed to name the Army's component of the project the Manhattan District. This became official on 13 August, when Reybold issued the order creating the new district. Informally, it was known as the Manhattan Engineer District, or MED. Unlike other districts, it had no geographic boundaries, and Marshall had the authority of a division engineer. 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. The recommended sites around , an isolated area where the could supply ample electric power and the rivers could provide cooling water for the reactors. After examining several sites, the survey team selected one near. 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 , 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. Nichols and Marshall were disappointed; AA-3 was the same priority as Nichols' TNT plant in Pennsylvania. Military Policy Committee and Groves at the remains of the in September 1945, two months after the test blast and just after the end of World War II. The white overshoes prevented 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 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. Groves' orders placed him directly under Somervell rather than Reybold, with Colonel Marshall now answerable to Groves. Groves established his headquarters in Washington, D. 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. Tolman and Conant were later appointed as Groves' scientific advisers. On 19 September, Groves went to , 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. 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. Most everything proposed in the Roosevelt administration would have top priority. One of Groves' early problems was to find a director for , the group that would design and build the bomb. The obvious choice was one of the three laboratory heads, Urey, Lawrence, or Compton, but they could not be spared. Compton recommended Oppenheimer, who was already intimately familiar with the bomb design concepts. However, Oppenheimer had little administrative experience, and, unlike Urey, Lawrence, and Compton, had not won a , which many scientists felt that the head of such an important laboratory should have. There were also concerns about Oppenheimer's security status, as many of his associates were , including his brother, ; his wife, Kitty; and his girlfriend,. 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 Main article: The British and Americans exchanged nuclear information but did not initially combine their efforts. Britain rebuffed attempts by Bush and Conant in 1941 to strengthen cooperation with its own project, codenamed , because it was reluctant to share its technological lead and help the United States develop its own atomic bomb. An American scientist who brought a personal letter from Roosevelt to Churchill offering to pay for all research and development in an Anglo-American project was poorly treated, and Churchill did not reply to the letter. The United States as a result decided as early as April 1942 that if its offer was rejected, they should proceed alone. The British, who had made significant contributions early in the war, did not have the resources to carry through such a research program while fighting for their survival. As a result, Tube Alloys soon fell behind its American counterpart. We now have a real contribution to make to a 'merger. Groves confers with , the head of the British Mission. The opportunity for an equal partnership no longer existed, however, as shown in August 1942 when the British unsuccessfully demanded substantial control over the project while paying none of the costs. By 1943 the roles of the two countries had reversed from late 1941; in January Conant notified the British that they would no longer receive atomic information except in certain areas. While the British were shocked by the abrogation of the Churchill-Roosevelt agreement, head of the Canadian C. The British bargaining position had worsened; the American scientists had decided that the United States no longer needed outside help, and they wanted to prevent Britain exploiting post-war commercial applications of atomic energy. The committee supported, and Roosevelt agreed to, restricting the flow of information to what Britain could use during the war—especially not bomb design—even if doing so slowed down the American project. By early 1943 the British stopped sending research and scientists to America, and as a result the Americans stopped all information sharing. The British considered ending the supply of Canadian uranium and heavy water to force the Americans to again share, but Canada needed American supplies to produce them. They investigated the possibility of an independent nuclear program, but determined that it could not be ready in time to affect the outcome of the. By March 1943 Conant decided that British help would benefit some areas of the project. In August 1943 Churchill and Roosevelt negotiated the , which resulted in a resumption of cooperation between scientists working on the same problem. Britain, however, agreed to restrictions on data on the building of large-scale production plants necessary for the bomb. The subsequent Hyde Park Agreement in September 1944 extended this cooperation to the postwar period. The Quebec Agreement established the 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 and Colonel were the British members, and was the Canadian member. Llewellin returned to the United Kingdom at the end of 1943 and was replaced on the committee by Sir , who in turn was replaced by the British Ambassador to the United States, , in early 1945. Sir John Dill died in Washington, D. When cooperation resumed after the Quebec agreement, the Americans' progress and expenditures amazed the British. Chadwick thus pressed for British involvement in the Manhattan Project to the fullest extent and abandon any hopes of a British project during the war. With Churchill's backing, he attempted to ensure that every request from Groves for assistance was honored. The British Mission that arrived in the United States in December 1943 included , Otto Frisch, , Rudolf Peierls, and. More scientists arrived in early 1944. While those assigned to gaseous diffusion left by the fall of 1944, the 35 working with Lawrence at Berkeley were assigned to existing laboratory groups and stayed until the end of the war. The 19 sent to Los Alamos also joined existing groups, primarily related to implosion and bomb assembly, but not the plutonium-related ones. 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 in June 1944, with Groves as its chairman, to procure uranium and on international markets. The and Canada held much of the world's uranium outside Eastern Europe, and the was in London. Britain agreed to give the United States most of the Belgian ore, as it could not use most of the supply without restricted American research. In 1944, the 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 on the project, a special account not subject to the usual auditing and controls was used to hold Trust monies. Groves appreciated the early British atomic research and the British scientists' contributions to the Manhattan Project, but stated that the United States would have succeeded without them. He just stirred him up all the time by telling him how important he thought the project was. Shift change at the Y-12 uranium enrichment facility at the in on 11 August 1945. By May 1945, 82,000 people were employed at the Clinton Engineer Works. Photograph by the Manhattan District photographer. The day after he took over the project, Groves took a train to Tennessee with Colonel Marshall to inspect the proposed site there, and Groves was impressed. 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 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 in the 1920s or the in the 1930s. When presented with Public Proclamation Number Two, which declared Oak Ridge a total exclusion area that no one could enter without military permission, the , , angrily tore it up. Initially known as the Kingston Demolition Range, the site was officially renamed the CEW in early 1943. The community was located on the slopes of Black Oak Ridge, from which the new town of got its name. 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. In September 1943 the administration of community facilities was outsourced to through a subsidiary, the Roane-Anderson Company for and Counties, in which Oak Ridge was located. Chemical engineers, including William J. The population of Oak Ridge soon expanded well beyond the initial plans, and peaked at 75,000 in May 1945, by which time 82,000 people were employed at the Clinton Engineer Works, and 10,000 by Roane-Anderson. Fine-arts photographer, , and her colleague, Mary Steers, helped document the work at Oak Ridge. Los Alamos The idea of locating Project Y at Oak Ridge was considered, but in the end it was decided that it should be in a remote location. On Oppenheimer's recommendation, the search for a suitable site was narrowed to the vicinity of , 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. 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. Oppenheimer was impressed and expressed a strong preference for the site, citing its natural beauty and views of the , which, it was hoped, would inspire those who would work on the project. The engineers were concerned about the poor access road, and whether the water supply would be adequate, but otherwise felt that it was ideal. Physicists at a Manhattan District-sponsored colloquium at the on the in April 1946. In the front row are , , and J. The Army officer on the left is Colonel. 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. Construction was contracted to the M. Sundt Company of , with of , as architect and engineer. Work commenced in December 1942. Birth certificates of babies born in Los Alamos during the war listed their place of birth as PO Box 1663 in Santa Fe. Initially Los Alamos was to have been 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, and , balked at the idea. Conant, Groves and Oppenheimer then devised a compromise whereby the laboratory was operated by the University of California under contract to the War Department. Chicago Main article: An Army-OSRD council on 25 June 1942 decided to build a for plutonium production in southwest of Chicago. In July, Nichols arranged for a lease of 1,025 acres 415 ha from the , and Captain James F. Grafton was appointed Chicago area engineer. It soon became apparent that the scale of operations was too great for the area, and it was decided to build the plant at Oak Ridge, and keep a research and testing facility in Chicago. Delays in establishing the plant in Red Gate Woods led Compton to authorize the Metallurgical Laboratory to construct the first nuclear reactor beneath the of at the University of Chicago. The reactor required an enormous amount of blocks and uranium pellets. At the time, there was a limited source of pure. Additional three short tons of uranium metal was supplied by which was produced in a rush with makeshift process. A large square balloon was constructed by to encase the reactor. On 2 December 1942, a team led by Enrico Fermi initiated the first artificial self-sustaining nuclear chain reaction in an experimental reactor known as. Compton reported the success to Conant in Washington, D. Peterson, ordered Chicago Pile-1 dismantled and reassembled at Red Gate Woods, as he regarded the operation of a reactor as too hazardous for a densely populated area. At the Argonne site, , the first heavy water reactor, went critical on 15 May 1944. After the war, the operations that remained at Red Gate moved to the new site of the about 6 miles 9. Hanford Main article: By December 1942 there were concerns that even Oak Ridge was too close to a major population center Knoxville in the unlikely event of a major nuclear accident. Groves recruited in November 1942 to be the prime contractor for the construction of the plutonium production complex. DuPont was offered a standard , but the President of the company, , wanted no profit of any kind, and asked for the proposed contract to be amended to explicitly exclude the company from acquiring any patent rights. This was accepted, but for legal reasons a nominal fee of one dollar was agreed upon. After the war, DuPont asked to be released from the contract early, and had to return 33 cents. Hanford workers collect their paychecks at the Western Union office. DuPont recommended that the site be located far from the existing uranium production facility at Oak Ridge. In December 1942, Groves dispatched Colonel and DuPont engineers to scout potential sites. It was isolated and near the , which could supply sufficient water to cool the reactors that would produce the plutonium. The federal government relocated some 1,500 residents of and , and nearby settlements, as well as the and other tribes using the area. A dispute arose with farmers over compensation for crops, which had already been planted before the land was acquired. Where schedules allowed, the Army allowed the crops to be harvested, but this was not always possible. The land acquisition process dragged on and was not completed before the end of the Manhattan Project in December 1946. The dispute did not delay work. Although progress on the reactor design at Metallurgical Laboratory and DuPont was not sufficiently advanced to accurately predict the scope of the project, a start was made in April 1943 on facilities for an estimated 25,000 workers, half of whom were expected to live on-site. By July 1944, some 1,200 buildings had been erected and nearly 51,000 people were living in the construction camp. As area engineer, Matthias exercised overall control of the site. At its peak, the construction camp was the third most populous town in Washington state. Hanford operated a fleet of over 900 buses, more than the city of Chicago. Like Los Alamos and Oak Ridge, Richland was a gated community with restricted access, but it looked more like a typical wartime American boomtown: the military profile was lower, and physical security elements like high fences, towers, and guard dogs were less evident. Canadian sites Main article: British Columbia had produced electrolytic hydrogen at , since 1930. Urey suggested in 1941 that it could produce heavy water. For this process, Hugh Taylor of Princeton developed a platinum-on-carbon for the first three stages while Urey developed a nickel- one for the fourth stage tower. The Canadian Government did not officially learn of the project until August 1942. Trail's heavy water production started in January 1944 and continued until 1956. Heavy water from Trail was used for , the first reactor using heavy water and natural uranium, which went critical on 15 May 1944. Ontario The , site was established to rehouse the Allied effort at the away from an urban area. A new community was built at , to provide residences and facilities for the team members. The site was chosen for its proximity to the industrial manufacturing area of Ontario and Quebec, and proximity to a rail head adjacent to a large military base,. Located on the Ottawa River, it had access to abundant water. The first director of the new laboratory was. He was replaced by John Cockcroft in May 1944, who in turn was succeeded by in September 1946. A pilot reactor known as zero-energy experimental pile became the first Canadian reactor, and the first to be completed outside the United States, when it went critical in September 1945, ZEEP remained in use by researchers until 1970. A larger 10 MW reactor, which was designed during the war, was completed and went critical in July 1947. Northwest Territories The at was a source of uranium ore. Heavy water sites Main article: Although DuPont's preferred designs for the nuclear reactors were helium cooled and used graphite as a moderator, DuPont still expressed an interest in using heavy water as a backup, in case the graphite reactor design proved infeasible for some reason. For this purpose, it was estimated that 3 short tons 2. The was the government's code name for the heavy water production program. As the plant at Trail, which was then under construction, could produce 0. Groves therefore authorized DuPont to establish heavy water facilities at the Morgantown Ordnance Works, near ; at the , near and ; and at the , near and. Although known as Ordnance Works and paid for under contracts, they were built and operated by the Army Corps of Engineers. The American plants used a process different from Trail's; heavy water was extracted by distillation, taking advantage of the slightly higher boiling point of heavy water. Ore The key raw material for the project was uranium, which was used as fuel for the reactors, as feed that was transformed into plutonium, and, in its enriched form, in the atomic bomb itself. There were four known major deposits of uranium in 1940: in Colorado, in northern Canada, in in Czechoslovakia, and in the. All but Joachimstal were in allied hands. A November 1942 survey determined that sufficient quantities of uranium were available to satisfy the project's requirements. Nichols arranged with the for export controls to be placed on and negotiated for the purchase of 1,200 short tons 1,100 t of uranium ore from the Belgian Congo that was being stored in a warehouse on and the remaining stocks of mined ore stored in the Congo. He negotiated with for the purchase of ore from its refinery in Port Hope, Ontario, and its shipment in 100-ton lots. The Canadian government subsequently bought up the company's stock until it acquired a controlling interest. While these purchases assured a sufficient supply to meet wartime needs, the American and British leaders concluded that it was in their countries' interest to gain control of as much of the world's uranium deposits as possible. The richest source of ore was the mine in the Belgian Congo, but it was flooded and closed. Nichols unsuccessfully attempted to negotiate its reopening and the sale of the entire future output to the United States with , the director of the company that owned the mine,. The matter was then taken up by the Combined Policy Committee. As 30 percent of Union Minière's stock was controlled by British interests, the British took the lead in negotiations. To avoid dependence on the British and Canadians for ore, Groves also arranged for the purchase of US Vanadium Corporation's stockpile in. Louis, Missouri, took the raw ore and dissolved it in to produce. This was then heated to form , which was reduced to highly pure. By July 1942, Mallinckrodt was producing a ton of highly pure oxide a day, but turning this into uranium metal initially proved more difficult for contractors and Metal Hydrides. Production was too slow and quality was unacceptably low. A special branch of the Metallurgical Laboratory was established at in , under Frank Spedding to investigate alternatives. This became known as the , and its became available in 1943. The chemically identical uranium-235 has to be physically separated from the more plentiful isotope. Various methods were considered for , most of which was carried out at Oak Ridge. The most obvious technology, the centrifuge, failed, but electromagnetic separation, gaseous diffusion, and thermal diffusion technologies were all successful and contributed to the project. In February 1943, Groves came up with the idea of using the output of some plants as the input for others. Oak Ridge hosted several uranium separation technologies. The Y-12 electromagnetic separation plant is in the upper right. The K-25 and K-27 gaseous diffusion plants are in the lower left, near the S-50 thermal diffusion plant. The X-10 was for plutonium production. Centrifuges The centrifuge process was regarded as the only promising separation method in April 1942. The process required high rotational speeds, but at certain speeds harmonic vibrations developed that threatened to tear the machinery apart. It was therefore necessary to accelerate quickly through these speeds. In 1941 he began working with , the only known gaseous compound of uranium, and was able to separate uranium-235. At Columbia, Urey had Karl Cohen investigate the process, and he produced a body of mathematical theory making it possible to design a centrifugal separation unit, which Westinghouse undertook to construct. Scaling this up to a production plant presented a formidable technical challenge. Urey and Cohen estimated that producing a kilogram 2. The prospect of keeping so many rotors operating continuously at high speed appeared daunting, and when Beams ran his experimental apparatus, he obtained only 60% of the predicted yield, indicating that more centrifuges would be required. Beams, Urey and Cohen then began work on a series of improvements which promised to increase the efficiency of the process. However, frequent failures of motors, shafts and bearings at high speeds delayed work on the pilot plant. In November 1942 the centrifuge process was abandoned by the Military Policy Committee following a recommendation by Conant, Nichols and August C. Electromagnetic separation Main article: Electromagnetic isotope separation was developed by Lawrence at the University of California Radiation Laboratory. This method employed devices known as , a hybrid of the standard laboratory and cyclotron. The name was derived from the words California, university and cyclotron. In the electromagnetic process, a magnetic field deflected charged particles according to mass. The process was neither scientifically elegant nor industrially efficient. Compared with a gaseous diffusion plant or a nuclear reactor, an electromagnetic separation plant would consume more scarce materials, require more manpower to operate, and cost more to build. Nonetheless, the process was approved because it was based on proven technology and therefore represented less risk. Moreover, it could be built in stages, and rapidly reach industrial capacity. Alpha I racetrack at Y-12 Marshall and Nichols discovered that the electromagnetic isotope separation process would require 5,000 short tons 4,500 tonnes of copper, which was in desperately short supply. However, silver could be substituted, in an 11:10 ratio. On 3 August 1942, Nichols met with and asked for the transfer of 6,000 tons of silver bullion from the. The 1,000-troy-ounce 31 kg silver bars were cast into cylindrical billets and taken to in Bayway, New Jersey, where they were extruded into strips 0. These were wound onto magnetic coils by in Milwaukee, Wisconsin. After the war, all the machinery was dismantled and cleaned and the floorboards beneath the machinery were ripped up and burned to recover minute amounts of silver. The last silver was returned in May 1970. The design called for five first-stage processing units, known as Alpha racetracks, and two units for final processing, known as Beta racetracks. In September 1943 Groves authorized construction of four more racetracks, known as Alpha II. Construction began in February 1943. When the plant was started up for testing on schedule in October, the 14-ton vacuum tanks crept out of alignment because of the power of the magnets, and had to be fastened more securely. A more serious problem arose when the magnetic coils started shorting out. In December Groves ordered a magnet to be broken open, and handfuls of rust were found inside. Groves then ordered the racetracks to be torn down and the magnets sent back to the factory to be cleaned. A pickling plant was established on-site to clean the pipes and fittings. The second Alpha I was not operational until the end of January 1944, the first Beta and first and third Alpha I's came online in March, and the fourth Alpha I was operational in April. The four Alpha II racetracks were completed between July and October 1944. Gladys Owens, seated in the foreground, was unaware of what she had been involved with until seeing this photo on a public tour of the facility 50 years later. The calutrons were initially operated by scientists from Berkeley to remove bugs and achieve a reasonable operating rate. They were then turned over to trained Tennessee Eastman operators who had only a high school education. They agreed to a production race and Lawrence lost, a morale boost for the Tennessee Eastman workers and supervisors. Only 1 part in 5,825 of the uranium feed emerged as final product. Much of the rest was splattered over equipment in the process. Strenuous recovery efforts helped raise production to 10% of the uranium-235 feed by January 1945. In February the Alpha racetracks began receiving slightly enriched 1. The next month it received enhanced 5% feed from the K-25 gaseous diffusion plant. By August K-25 was producing uranium sufficiently enriched to feed directly into the Beta tracks. Gaseous diffusion Main article: The most promising but also the most challenging method of isotope separation was gaseous diffusion. The gas leaving the container is somewhat enriched in the lighter molecules, while the residual gas is somewhat depleted. The idea was that such boxes could be formed into a cascade of pumps and membranes, with each successive stage containing a slightly more enriched mixture. Research into the process was carried out at Columbia University by a group that included Harold Urey, , and. Oak Ridge K-25 plant In November 1942 the Military Policy Committee approved the construction of a 600-stage gaseous diffusion plant. On 14 December, accepted an offer to construct the plant, which was codenamed K-25. A separate corporate entity called Kellex was created for the project, headed by Percival C. Keith, one of Kellogg's vice presidents. The process faced formidable technical difficulties. The highly corrosive gas uranium hexafluoride would have to be used, as no substitute could be found, and the motors and pumps would have to be vacuum tight and enclosed in inert gas. The biggest problem was the design of the barrier, which would have to be strong, porous and resistant to corrosion by uranium hexafluoride. The best choice for this seemed to be nickel. Edward Adler and Edward Norris created a mesh barrier from electroplated nickel. A six-stage pilot plant was built at Columbia to test the process, but the Norris-Adler prototype proved to be too brittle. A rival barrier was developed from powdered nickel by Kellex, the and the Corporation. In January 1944, Groves ordered the Kellex barrier into production. Kellex's design for K-25 called for a four-story 0. These were divided into nine sections. Within these were cells of six stages. The cells could be operated independently, or consecutively within a section. Similarly, the sections could be operated separately or as part of a single cascade. A survey party began construction by marking out the 500-acre 2. Work on the main building began in October 1943, and the six-stage pilot plant was ready for operation on 17 April 1944. In 1945 Groves canceled the upper stages of the plant, directing Kellex to instead design and build a 540-stage side feed unit, which became known as K-27. Kellex transferred the last unit to the operating contractor, , on 11 September 1945. The production plant commenced operation in February 1945, and as cascade after cascade came online, the quality of the product increased. By April 1945, K-25 had attained a 1. Some product produced the next month reached nearly 7% enrichment. In August, the last of the 2,892 stages commenced operation. K-25 and K-27 achieved their full potential in the early postwar period, when they eclipsed the other production plants and became the prototypes for a new generation of plants. Thermal diffusion Main article: The thermal diffusion process was based on and 's , which explained that when a mixed gas passes through a temperature gradient, the heavier one tends to concentrate at the cold end and the lighter one at the warm end. Since hot gases tend to rise and cool ones tend to fall, this can be used as a means of isotope separation. This process was first demonstrated by and Gerhard Dickel in Germany in 1938. It was developed by US Navy scientists, but was not one of the enrichment technologies initially selected for use in the Manhattan Project. This was primarily due to doubts about its technical feasibility, but the inter-service rivalry between the Army and Navy also played a part. The S-50 plant is the dark building to the upper left behind the Oak Ridge powerhouse with smoke stacks. The Naval Research Laboratory continued the research under Philip Abelson's direction, but there was little contact with the Manhattan Project until April 1944, when , the naval officer in charge of ordnance development at Los Alamos, brought Oppenheimer news of encouraging progress in the Navy's experiments on thermal diffusion. Oppenheimer wrote to Groves suggesting that the output of a thermal diffusion plant could be fed into Y-12. Groves approved its construction on 24 June 1944. Groves contracted with the H. Ferguson Company of , to build the thermal diffusion plant, which was designated S-50. Groves's advisers, Karl Cohen and W. Thompson from , estimated that it would take six months to build. Groves gave Ferguson just four. Plans called for the installation of 2,142 48-foot-tall 15 m diffusion columns arranged in 21 racks. Inside each column were three concentric tubes. Steam, obtained from the nearby K-25 powerhouse at a pressure of 1,000 pounds per square inch 6,900 kPa and temperature of 545 °F 285 °C , flowed downward through the innermost 1. Isotope separation occurred in the uranium hexafluoride gas between the nickel and copper pipes. Work commenced on 9 July 1944, and S-50 began partial operation in September. Ferguson operated the plant through a subsidiary known as Fercleve. The plant produced just 10. Leaks limited production and forced shutdowns over the next few months, but in June 1945 it produced 12,730 pounds 5,770 kg. By March 1945, all 21 production racks were operating. Initially the output of S-50 was fed into Y-12, but starting in March 1945 all three enrichment processes were run in series. S-50 became the first stage, enriching from 0. This material was fed into the gaseous diffusion process in the K-25 plant, which produced a product enriched to about 23%. This was, in turn, fed into Y-12, which boosted it to about 89%, sufficient for nuclear weapons. Aggregate U-235 production About 50 kilograms 110 lb of uranium enriched to 89% uranium-235 was delivered to Los Alamos by July 1945. The entire 50 kg, along with some 50%-enriched, averaging out to about 85% enriched, were used in. The second line of development pursued by the Manhattan Project used the fissile element plutonium. Although small amounts of plutonium exist in nature, the best way to obtain large quantities of the element is in a nuclear reactor, in which natural uranium is bombarded by neutrons. The uranium-238 is into , which rapidly decays, first into and then into. Only a small amount of the uranium-238 will be transformed, so the plutonium must be chemically separated from the remaining uranium, from any initial impurities, and from. X-10 Graphite Reactor Workers load uranium slugs into the X-10 Graphite Reactor. In March 1943, DuPont began construction of a plutonium plant on a 112-acre 0. Intended as a pilot plant for the larger production facilities at Hanford, it included the air-cooled , a chemical separation plant, and support facilities. Because of the subsequent decision to construct water-cooled reactors at Hanford, only the chemical separation plant operated as a true pilot. The X-10 Graphite Reactor consisted of a huge block of graphite, 24 feet 7. The greatest difficulty was encountered with the uranium slugs produced by Mallinckrodt and Metal Hydrides. These somehow had to be coated in aluminum to avoid corrosion and the escape of fission products into the cooling system. The Grasselli Chemical Company attempted to develop a without success. A new process for flux-less welding was developed, and 97% of the cans passed a standard vacuum test, but high temperature tests indicated a failure rate of more than 50%. Nonetheless, production began in June 1943. The Metallurgical Laboratory eventually developed an improved welding technique with the help of , which was incorporated into the production process in October 1943. Watched by Fermi and Compton, the X-10 Graphite Reactor went critical on 4 November 1943 with about 30 short tons 27 t of uranium. A week later the load was increased to 36 short tons 33 t , raising its power generation to 500 kW, and by the end of the month the first 500 mg of plutonium was created. Modifications over time raised the power to 4,000 kW in July 1944. X-10 operated as a production plant until January 1945, when it was turned over to research activities. Hanford reactors Main article: Although an air-cooled design was chosen for the reactor at Oak Ridge to facilitate rapid construction, it was recognized that this would be impractical for the much larger production reactors. Initial designs by the Metallurgical Laboratory and DuPont used helium for cooling, before they determined that a water-cooled reactor would be simpler, cheaper and quicker to build. The design did not become available until 4 October 1943; in the meantime, Matthias concentrated on improving the Hanford Site by erecting accommodations, improving the roads, building a railway switch line, and upgrading the electricity, water and telephone lines. Aerial view of Hanford site, June 1944 As at Oak Ridge, the most difficulty was encountered while canning the uranium slugs, which commenced at Hanford in March 1944. They were to remove dirt and impurities, dipped in molten bronze, tin, and , canned using hydraulic presses, and then capped using under an argon atmosphere. Finally, they were subjected to a series of tests to detect holes or faulty welds. Disappointingly, most canned slugs initially failed the tests, resulting in an output of only a handful of canned slugs per day. But steady progress was made and by June 1944 production increased to the point where it appeared that enough canned slugs would be available to start on schedule in August 1944. Work began on Reactor B, the first of six planned 250 MW reactors, on 10 October 1943. The reactor complexes were given letter designations A through F, with B, D and F sites chosen to be developed first, as this maximised the distance between the reactors. They would be the only ones constructed during the Manhattan Project. Some 390 short tons 350 t of steel, 17,400 cubic yards 13,300 m 3 of concrete, 50,000 concrete blocks and 71,000 concrete bricks were used to construct the 120-foot 37 m high building. Construction of the reactor itself commenced in February 1944. Watched by Compton, Matthias, DuPont's , and Fermi, who inserted the first slug, the reactor was powered up beginning on 13 September 1944. Over the next few days, 838 tubes were loaded and the reactor went critical. Shortly after midnight on 27 September, the operators began to withdraw the to initiate production. At first all appeared well but around 03:00 the power level started to drop and by 06:30 the reactor had shut down completely. The cooling water was investigated to see if there was a leak or contamination. The next day the reactor started up again, only to shut down once more. Fermi contacted , who identified the cause of the problem as from , which has a of 9. Fermi, Woods, and then calculated the of xenon-135, which turned out to be 30,000 times that of uranium. Fortunately, DuPont engineer George Graves had deviated from the Metallurgical Laboratory's original design in which the reactor had 1,500 tubes arranged in a circle, and had added an additional 504 tubes to fill in the corners. The scientists had originally considered this overengineering a waste of time and money, but Fermi realized that by loading all 2,004 tubes, the reactor could reach the required power level and efficiently produce plutonium. Reactor D was started on 17 December 1944 and Reactor F on 25 February 1945. Separation process Map of the Hanford Site. Railroads flank the plants to the north and south. Reactors are the three northernmost red squares, along the Columbia River. The separation plants are the lower two red squares from the grouping south of the reactors. The bottom red square is the 300 area. Meanwhile, the chemists considered the problem of how plutonium could be separated from uranium when its chemical properties were not known. Working with the minute quantities of plutonium available at the Metallurgical Laboratory in 1942, a team under Charles M. Cooper developed a for separating uranium and plutonium, which was chosen for the pilot separation plant. A second separation process, the , was subsequently developed by Seaborg and Stanly G. This process worked by toggling plutonium between its +4 and +6 in solutions of bismuth phosphate. In the former state, the plutonium was precipitated; in the latter, it stayed in solution and the other products were precipitated. Greenewalt favored the bismuth phosphate process due to the corrosive nature of lanthanum fluoride, and it was selected for the Hanford separation plants. Once X-10 began producing plutonium, the pilot separation plant was put to the test. The first batch was processed at 40% efficiency but over the next few months this was raised to 90%. At Hanford, top priority was initially given to the installations in the 300 area. This contained buildings for testing materials, preparing uranium, and assembling and calibrating instrumentation. One of the buildings housed the canning equipment for the uranium slugs, while another contained a small test reactor. Notwithstanding the high priority allocated to it, work on the 300 area fell behind schedule due to the unique and complex nature of the 300 area facilities, and wartime shortages of labor and materials. Early plans called for the construction of two separation plants in each of the areas known as 200-West and 200-East. This was subsequently reduced to two, the T and U plants, in 200-West and one, the B plant, at 200-East. The canyons were each 800 feet 240 m long and 65 feet 20 m wide. Each consisted of forty 17. Work began on 221-T and 221-U in January 1944, with the former completed in September and the latter in December. The 221-B building followed in March 1945. Because of the high levels of radioactivity involved, all work in the separation plants had to be conducted by remote control using closed-circuit television, something unheard of in 1943. Maintenance was carried out with the aid of an overhead crane and specially designed tools. The 224 buildings were smaller because they had less material to process, and it was less radioactive. The 224-T and 224-U buildings were completed on 8 October 1944, and 224-B followed on 10 February 1945. The purification methods that were eventually used in 231-W were still unknown when construction commenced on 8 April 1944, but the plant was complete and the methods were selected by the end of the year. On 5 February 1945, Matthias hand-delivered the first shipment of 80 g of 95%-pure plutonium nitrate to a Los Alamos courier in Los Angeles. Weapon design A row of Thin Man casings. Fat Man casings are visible in the background. In 1943, development efforts were directed to a with plutonium called. Initial research on the properties of plutonium was done using cyclotron-generated plutonium-239, which was extremely pure, but could only be created in very small amounts. Los Alamos received the first sample of plutonium from the Clinton X-10 reactor in April 1944 and within days Emilio Segrè discovered a problem: the reactor-bred plutonium had a higher concentration of plutonium-240, resulting in up to five times the spontaneous fission rate of cyclotron plutonium. Seaborg had correctly predicted in March 1943 that some of the plutonium-239 would absorb a neutron and become plutonium-240. This made reactor plutonium unsuitable for use in a gun-type weapon. The plutonium-240 would start the chain reaction too quickly, causing a that would release enough energy to disperse the critical mass with a minimal amount of plutonium reacted a. A faster gun was suggested but found to be impractical. The possibility of separating the isotopes was considered and rejected, as plutonium-240 is even harder to separate from plutonium-239 than uranium-235 from uranium-238. Work on an alternative method of bomb design, known as implosion, had begun earlier under the direction of the physicist. Implosion used explosives to crush a subcritical sphere of fissile material into a smaller and denser form. When the fissile atoms are packed closer together, the rate of neutron capture increases, and the mass becomes a critical mass. The metal needs to travel only a very short distance, so the critical mass is assembled in much less time than it would take with the gun method. Neddermeyer's 1943 and early 1944 investigations into implosion showed promise, but also made it clear that the problem would be much more difficult from a theoretical and engineering perspective than the gun design. In September 1943, , who had experience with used in armor-piercing shells, argued that not only would implosion reduce the danger of predetonation and fizzle, but would make more efficient use of the fissionable material. He proposed using a spherical configuration instead of the cylindrical one that Neddermeyer was working on. An implosion-type nuclear bomb By July 1944, Oppenheimer had concluded plutonium could not be used in a gun design, and opted for implosion. The accelerated effort on an implosion design, codenamed , began in August 1944 when Oppenheimer implemented a sweeping reorganization of the Los Alamos laboratory to focus on implosion. Two new groups were created at Los Alamos to develop the implosion weapon, X for explosives Division headed by explosives expert and G for gadget Division under Robert Bacher. The new design that von Neumann and T for theoretical Division, most notably Rudolf Peierls, had devised used to focus the explosion onto a spherical shape using a combination of both slow and fast high explosives. The design of lenses that detonated with the proper shape and velocity turned out to be slow, difficult and frustrating. Various explosives were tested before settling on as the fast explosive and as the slow explosive. The final design resembled a soccer ball, with 20 hexagonal and 12 pentagonal lenses, each weighing about 80 pounds 36 kg. Getting the detonation just right required fast, reliable and safe electrical , of which there were two for each lens for reliability. It was therefore decided to use , a new invention developed at Los Alamos by a group led by. A contract for their manufacture was given to. To study the behavior of converging , Robert Serber devised the , which used the short-lived , a potent source of. The gamma ray source was placed in the center of a metal sphere surrounded by the explosive lenses, which in turn were inside in an. This allowed the taking of an X-ray movie of the implosion. The lenses were designed primarily using this series of tests. Within the explosives was the 4. Its main job was to hold the critical mass together as long as possible, but it would also reflect neutrons back into the core. Some part of it might fission as well. To prevent predetonation by an external neutron, the tamper was coated in a thin layer of boron. This work with the chemistry and metallurgy of radioactive polonium was directed by of the and became known as the. Testing required up to 500 per month of polonium, which Monsanto was able to deliver. The whole assembly was encased in a bomb casing to protect it from bullets and flak. Remote handling of a kilocurie source of radiolanthanum for a at Los Alamos The ultimate task of the metallurgists was to determine how to cast plutonium into a sphere. The difficulties became apparent when attempts to measure the density of plutonium gave inconsistent results. At first contamination was believed to be the cause, but it was soon determined that there were multiple. The brittle α phase that exists at room temperature changes to the plastic β phase at higher temperatures. Attention then shifted to the even more malleable δ phase that normally exists in the 300 °C to 450 °C range. It was found that this was stable at room temperature when alloyed with aluminum, but aluminum emits neutrons when bombarded with , which would exacerbate the pre-ignition problem. The metallurgists then hit upon a , which stabilized the δ phase and could be into the desired spherical shape. As plutonium was found to corrode readily, the sphere was coated with nickel. The work proved dangerous. By the end of the war, half the experienced chemists and metallurgists had to be removed from work with plutonium when unacceptably high levels of the element appeared in their urine. A minor fire at Los Alamos in January 1945 led to a fear that a fire in the plutonium laboratory might contaminate the whole town, and Groves authorized the construction of a new facility for plutonium chemistry and metallurgy, which became known as the DP-site. The hemispheres for the first plutonium or core were produced and delivered on 2 July 1945. Three more hemispheres followed on 23 July and were delivered three days later. Trinity Main article: Because of the complexity of an implosion-style weapon, it was decided that, despite the waste of fissile material, an initial test would be required. Groves approved the test, subject to the active material being recovered. In March 1944, planning for the test was assigned to , a professor of physics at Harvard, working under Kistiakowsky. Bainbridge selected the near as the site for the test. Bainbridge worked with Captain Samuel P. Davalos on the construction of the Trinity Base Camp and its facilities, which included barracks, warehouses, workshops, an explosive magazine and a commissary. Measuring 25 feet 7. Brought in a special railroad car to a siding in Pope, New Mexico, it was transported the last 25 miles 40 km to the test site on a trailer pulled by two tractors. By the time it arrived, however, confidence in the implosion method was high enough, and the availability of plutonium was sufficient, that Oppenheimer decided not to use it. Instead, it was placed atop a steel tower 800 yards 730 m from the weapon as a rough measure of how powerful the explosion would be. In the end, Jumbo survived, although its tower did not, adding credence to the belief that Jumbo would have successfully contained a fizzled explosion. A pre-test explosion was conducted on 7 May 1945 to calibrate the instruments. A wooden test platform was erected 800 yards 730 m from Ground Zero and piled with 100 short tons 91 t of TNT spiked with in the form of an irradiated uranium slug from Hanford, which was dissolved and poured into tubing inside the explosive. This explosion was observed by Oppenheimer and Groves's new deputy commander, Brigadier General. The pre-test produced data that proved vital for the Trinity test. Detonation in the air maximized the energy applied directly to the target, and generated less. The gadget was assembled under the supervision of at the nearby on 13 July, and precariously winched up the tower the following day. Observers included Bush, Chadwick, Conant, Farrell, Fermi, Groves, Lawrence, Oppenheimer and Tolman. At 05:30 on 16 July 1945 the gadget exploded with an of around 20 kilotons of TNT, leaving a crater of radioactive glass in the desert 250 feet 76 m wide. The shock wave was felt over 100 miles 160 km away, and the reached 7. It was heard as far away as , so Groves issued a cover story about an ammunition magazine explosion at Alamogordo Field. The of the Manhattan Project was the first detonation of a. Oppenheimer later recalled that, while witnessing the explosion, he thought of a verse from the holy book, the XI,12 : कालोऽस्मि लोकक्षयकृत्प्रवृद्धो लोकान्समाहर्तुमिह प्रवृत्तः। ऋतेऽपि त्वां न भविष्यन्ति सर्वे येऽवस्थिताः प्रत्यनीकेषु योधाः॥११- ३२॥ If the radiance of a thousand suns were to burst at once into the sky, that would be like the splendor of the mighty one... Years later he would explain that another verse had also entered his head at that time: We knew the world would not be the same. A few people laughed, a few people cried. Most people were silent. I remembered the line from the Hindu scripture, the Bhagavad Gita; is trying to persuade the that he should do his duty and, to impress him, takes on and says, 'Now I am become Death, the destroyer of worlds. In June 1944, the Manhattan Project employed some 129,000 workers, of whom 84,500 were construction workers, 40,500 were plant operators and 1,800 were military personnel. As construction activity fell off, the workforce declined to 100,000 a year later, but the number of military personnel increased to 5,600. Procuring the required numbers of workers, especially highly skilled workers, in competition with other vital wartime programs proved very difficult. In 1943, Groves obtained a special temporary priority for labor from the. In March 1944, both the War Production Board and the War Manpower Commission gave the project their highest priority. Major General Leslie R. Tolman and Conant, in their role as the project's scientific advisers, drew up a list of candidate scientists and had them rated by scientists already working on the project. Groves then sent a personal letter to the head of their university or company asking for them to be released for essential war work. At the , gave one of his students, , an exam early, so she could leave to do war work. A few weeks later, Ulam received a letter from Hans Bethe, inviting him to join the project. Conant personally persuaded Kistiakowsky to join the project. One source of skilled personnel was the Army itself, particularly the. In 1943, the MED created the SED , with an authorized strength of 675. Technicians and skilled workers drafted into the Army were assigned to the SED. Another source was the Women's Army Corps WAC. Initially intended for clerical tasks handling classified material, the WACs were soon tapped for technical and scientific tasks as well. On 1 February 1945, all military personnel assigned to the MED, including all SED detachments, were assigned to the 9812th Technical Service Unit, except at Los Alamos, where military personnel other than SED, including the WACs and Military Police, were assigned to the 4817th Service Command Unit. An Associate Professor of at the , , was commissioned as a colonel in the , and appointed as chief of the MED's Medical Section and Groves' medical advisor. Warren's initial task was to staff hospitals at Oak Ridge, Richland and Los Alamos. The Medical Section was responsible for medical research, but also for the MED's health and safety programs. This presented an enormous challenge, because workers were handling a variety of toxic chemicals, using hazardous liquids and gases under high pressures, working with high voltages, and performing experiments involving explosives, not to mention the largely unknown dangers presented by radioactivity and handling fissile materials. Yet in December 1945, the presented the Manhattan Project with the Award of Honor for Distinguished Service to Safety in recognition of its safety record. Between January 1943 and June 1945, there were 62 fatalities and 3,879 disabling injuries, which was about 62 percent below the rate of private industry. A billboard encouraging secrecy among Oak Ridge workers Oak Ridge security personnel considered any private party with more than seven people as suspicious, and residents—who believed that US government agents were secretly among them—avoided repeatedly inviting the same guests. Although original residents of the area could be buried in existing cemeteries, every coffin was reportedly opened for inspection. Everyone, including top military officials, and their automobiles were searched when entering and exiting project facilities. Usually those summoned to explain were then escorted bag and baggage to the gate and ordered to keep going. One manager stated after the war: Well it wasn't that the job was tough... You see, no one knew what was being made in Oak Ridge, not even me, and a lot of the people thought they were wasting their time here. It was up to me to explain to the dissatisfied workers that they were doing a very important job. When they asked me what, I'd have to tell them it was a secret. But I almost went crazy myself trying to figure out what was going on. She learned only after the war that she had been performing the important task of checking for radiation with a. To improve morale among such workers Oak Ridge created an extensive system of intramural sports leagues, including 10 baseball teams, 81 softball teams, and 26 football teams. Censorship Security poster, warning office workers to close drawers and put documents in safes when not being used Voluntary censorship of atomic information began before the Manhattan Project. After the start of the European war in 1939 American scientists began avoiding publishing military-related research, and in 1940 scientific journals began asking the to clear articles. The Soviets noticed the silence, however. In April 1942 nuclear physicist wrote to on the absence of articles on nuclear fission in American journals; this resulted in the Soviet Union establishing its own atomic bomb project. The Manhattan Project operated under tight security lest its discovery induce Axis powers, especially Germany, to accelerate their own nuclear projects or undertake covert operations against the project. The government's , by contrast, relied on the press to comply with a voluntary code of conduct it published, and the project at first avoided notifying the office. By early 1943 newspapers began publishing reports of large construction in Tennessee and Washington based on public records, and the office began discussing with the project how to maintain secrecy. The use for military purposes of radium or radioactive materials, heavy water, high voltage discharge equipment, cyclotrons. Soviet spies Main article: The prospect of sabotage was always present, and sometimes suspected when there were equipment failures. While there were some problems believed to be the result of careless or disgruntled employees, there were no confirmed instances of Axis-instigated sabotage. However, on 10 March 1945, a Japanese struck a power line, and the resulting power surge caused the three reactors at Hanford to be temporarily shut down. With so many people involved, security was a difficult task. A special detachment was formed to handle the project's security issues. By 1943, it was clear that the Soviet Union was attempting to penetrate the project. Lieutenant Colonel , the head of the Counter Intelligence Branch of the , investigated suspected Soviet espionage at the Radiation Laboratory in Berkeley. Oppenheimer informed Pash that he had been approached by a fellow professor at Berkeley, , about passing information to the Soviet Union. The most successful Soviet spy was , a member of the British Mission who played an important part at Los Alamos. The 1950 revelation of his espionage activities damaged the United States' nuclear cooperation with Britain and Canada. Subsequently, other instances of espionage were uncovered, leading to the arrest of , , and. Other spies like and remained unknown for decades. The value of the espionage is difficult to quantify, as the principal constraint on the was a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort. Main article: In addition to developing the atomic bomb, the Manhattan Project was charged with gathering intelligence on the. It was believed that the was not far advanced because Japan had little access to uranium ore, but it was initially feared that Germany was very close to developing its own weapons. At the instigation of the Manhattan Project, a was carried out against heavy water plants in German-occupied Norway. A small mission was created, jointly staffed by the , OSRD, the Manhattan Project, and Army Intelligence G-2 , to investigate enemy scientific developments. It was not restricted to those involving nuclear weapons. Allied soldiers dismantle the German experimental nuclear reactor at. The Alsos Mission to Italy questioned staff of the physics laboratory at the following the capture of the city in June 1944. Meanwhile, Pash formed a combined British and American Alsos mission in London under the command of Captain Horace K. Calvert to participate in. Groves considered the risk that the Germans might attempt to disrupt the with radioactive poisons was sufficient to warn General and send an officer to brief his chief of staff, Lieutenant General. Under the codename , special equipment was prepared and teams were trained in its use. Following in the wake of the advancing Allied armies, Pash and Calvert interviewed about the activities of German scientists. They spoke to officials at Union Minière du Haut Katanga about uranium shipments to Germany. They tracked down 68 tons of ore in Belgium and 30 tons in France. The interrogation of German prisoners indicated that uranium and thorium were being processed in , 20 miles north of Berlin, so Groves on 15 March 1945. An Alsos team went to in the and retrieved 11 tons of ore from. In April 1945, Pash, in command of a composite force known as T-Force, conducted , a sweep behind enemy lines of the cities of , , and that were the heart of the German nuclear effort. T-Force captured the nuclear laboratories, documents, equipment and supplies, including heavy water and 1. Alsos teams rounded up German scientists including , , , , and , who were taken to England where they were interned at , a bugged house in. After the bombs were detonated in Japan, the Germans were forced to confront the fact that the Allies had done what they could not. Main article: Preparations Starting in November 1943, the at , Ohio, began , the codename modification of B-29s to carry the bombs. Test drops were carried out at , California, and the. Groves met with the Chief of USAAF , General , in March 1944 to discuss the delivery of the finished bombs to their targets. The only Allied aircraft capable of carrying the 17-foot 5. Groves hoped that the American could be modified to carry Thin Man by joining its two together. Arnold promised that no effort would be spared to modify B-29s to do the job, and designated Major General as the USAAF liaison to the Manhattan Project. In turn, Echols named Colonel as his alternate, and Wilson became Manhattan Project's main USAAF contact. President Roosevelt instructed Groves that if the atomic bombs were ready before the war with Germany ended, he should be ready to drop them on Germany. The tail code of the is painted on for security reasons. The was activated on 17 December 1944 at , Utah, under the command of Colonel. Training was conducted at Wendover and at , Cuba, where the practiced long-distance flights over water, and dropping dummy. A special unit known as was formed at Los Alamos under Navy Captain from Project Y as part of the Manhattan Project to assist in preparing and delivering the bombs. Commander from Alberta met with Fleet Admiral on in February 1945 to inform him of the project. While he was there, Ashworth selected on the Pacific Island as a base for the 509th Composite Group, and reserved space for the group and its buildings. The group deployed there in July 1945. Farrell arrived at Tinian on 30 July as the Manhattan Project representative. Most of the components for Little Boy left San Francisco on the cruiser on 16 July and arrived on Tinian on 26 July. Four days later the ship was sunk by a Japanese submarine. The remaining components, which included six uranium-235 rings, were delivered by three of the 509th Group's 320th Troop Carrier Squadron. Two Fat Man assemblies travelled to Tinian in specially modified 509th Composite Group B-29s. The first went in a special C-54. A joint targeting committee of the Manhattan District and USAAF was established to determine which cities in Japan should be targets, and recommended , , , and. At this point, Henry L. Stimson intervened, announcing that he would be making the targeting decision, and that he would not authorize the bombing of Kyoto on the grounds of its historical and religious significance. Groves therefore asked Arnold to remove Kyoto not just from the list of nuclear targets, but from targets for conventional bombing as well. One of Kyoto's substitutes was. Bombings In May 1945, the was created to advise on wartime and postwar use of nuclear energy. The committee was chaired by Stimson, with , a former US Senator soon to be , as President 's personal representative; , the Under Secretary of the Navy; , the Assistant Secretary of State; Vannevar Bush; Karl T. Conant; and , an assistant to Stimson and president of. The Interim Committee in turn established a scientific panel consisting of Arthur Compton, Fermi, Lawrence and Oppenheimer to advise it on scientific issues. In its presentation to the Interim Committee, the scientific panel offered its opinion not just on the likely physical effects of an atomic bomb, but on its probable military and political impact. At the in Germany, Truman was informed that the Trinity test had been successful. He told Stalin, the leader of the , that the US had a new superweapon, without giving any details. This was the first official communication to the Soviet Union about the bomb, but Stalin already knew about it from spies. With the authorization to use the bomb against Japan already given, no alternatives were considered after the Japanese rejection of the. Little Boy explodes over , Japan, 6 August 1945 left ; Fat Man explodes over , Japan, 9 August 1945 right. On 6 August 1945, a Boeing B-29 Superfortress of the 393d Bombardment Squadron, piloted by Tibbets, lifted off from North Field, and Little Boy in its bomb bay. Hiroshima, the headquarters of the and and a port of embarkation, was the primary target of the mission, with Kokura and Nagasaki as alternatives. With Farrell's permission, Parsons, the weaponeer in charge of the mission, completed the bomb assembly in the air to minimize the risks during takeoff. The bomb detonated at an altitude of 1,750 feet 530 m with a blast that was later estimated to be the equivalent of 13 kilotons of TNT. An area of approximately 4. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6—7% damaged. About 70,000 to 80,000 people, of whom 20,000 were Japanese combatants and 20,000 were Korean slave laborers, or some 30% of the population of Hiroshima, were killed immediately, and another 70,000 injured. On the morning of 9 August 1945, a second B-29 , piloted by the 393d Bombardment Squadron's commander, Major , lifted off with Fat Man on board. This time, Ashworth served as weaponeer and Kokura was the primary target. Sweeney took off with the weapon already armed but with the electrical safety plugs still engaged. When they reached Kokura, they found cloud cover had obscured the city, prohibiting the visual attack required by orders. After three runs over the city, and with fuel running low, they headed for the secondary target, Nagasaki. Ashworth decided that a radar approach would be used if the target was obscured, but a last-minute break in the clouds over Nagasaki allowed a visual approach as ordered. The Fat Man was dropped over the city's industrial valley midway between the Mitsubishi Steel and Arms Works in the south and the Mitsubishi-Urakami Ordnance Works in the north. The resulting explosion had a blast yield equivalent to 21 kilotons of TNT, roughly the same as the Trinity blast, but was confined to the , and a major portion of the city was protected by the intervening hills, resulting in the destruction of about 44% of the city. The bombing also crippled the city's industrial production extensively and killed 23,200—28,200 Japanese industrial workers and 150 Japanese soldiers. Overall, an estimated 35,000—40,000 people were killed and 60,000 injured. Groves expected to have another atomic bomb ready for use on 19 August, with three more in September and a further three in October. Two more Fat Man assemblies were readied, and scheduled to leave for Tinian on 11 and 14 August. At Los Alamos, technicians worked 24 hours straight to cast. Although cast, it still needed to be pressed and coated, which would take until 16 August. It could therefore have been ready for use on 19 August. On 10 August, Truman secretly requested that additional atomic bombs not be dropped on Japan without his express authority. Groves suspended the third core's shipment on his own authority on 13 August. On 11 August, Groves phoned Warren with orders to organize a survey team to report on the damage and radioactivity at Hiroshima and Nagasaki. A party equipped with portable Geiger counters arrived in Hiroshima on 8 September headed by Farrell and Warren, with Japanese Rear Admiral Masao Tsuzuki, who acted as a translator. They remained in Hiroshima until 14 September and then surveyed Nagasaki from 19 September to 8 October. This and other scientific missions to Japan would provide valuable scientific and historical data. The necessity of the bombings of Hiroshima and Nagasaki became a. The was the most notable effort pushing for a demonstration but was turned down by the Interim Committee's scientific panel. The , drafted in July 1945 and signed by dozens of scientists working on the Manhattan Project, was a late attempt at warning President Harry S. Truman about his responsibility in using such weapons. Presentation of the at Los Alamos on 16 October 1945. Standing, left to right: , unidentified, unidentified, , , ,. In anticipation of the bombings, Groves had prepare a history for public consumption. Groves and Nichols presented to key contractors, whose involvement had hitherto been secret. Over 20 awards of the were made to key contractors and scientists, including Bush and Oppenheimer. Military personnel received the , including the commander of the detachment, Captain Arlene G. At Hanford, plutonium production fell off as Reactors B, D and F wore out, poisoned by fission products and swelling of the graphite moderator known as the. The swelling damaged the charging tubes where the uranium was irradiated to produce plutonium, rendering them unusable. In order to maintain the supply of polonium for the urchin initiators, production was curtailed and the oldest unit, B pile, was closed down so at least one reactor would be available in the future. Research continued, with DuPont and the Metallurgical Laboratory developing a solvent extraction process as an alternative technique to the bismuth phosphate process, which left unspent uranium in a state from which it could not easily be recovered. Bomb engineering was carried out by the Z Division, named for its director, Dr. Z Division was initially located at Wendover Field but moved to , New Mexico, in September 1945 to be closer to Los Alamos. This marked the beginning of. Nearby Kirtland Field was used as a B-29 base for aircraft compatibility and drop tests. By October, all the staff and facilities at Wendover had been transferred to Sandia. As reservist officers were demobilized, they were replaced by about fifty hand-picked regular officers. Nichols recommended that S-50 and the Alpha tracks at Y-12 be closed down. This was done in September. Although performing better than ever, the Alpha tracks could not compete with K-25 and the new K-27, which had commenced operation in January 1946. President signs the , establishing the. Nowhere was demobilization more of a problem than at Los Alamos, where there was an exodus of talent. Much remained to be done. The bombs used on Hiroshima and Nagasaki were like laboratory pieces; work would be required to make them simpler, safer and more reliable. Implosion methods needed to be developed for uranium in place of the wasteful gun method, and composite uranium-plutonium cores were needed now that plutonium was in short supply because of the problems with the reactors. However, uncertainty about the future of the laboratory made it hard to induce people to stay. Oppenheimer returned to his job at the University of California and Groves appointed Norris Bradbury as an interim replacement. In fact, Bradbury would remain in the post for the next 25 years. Groves attempted to combat the dissatisfaction caused by the lack of amenities with a construction program that included an improved water supply, three hundred houses, and recreation facilities. Two Fat Man—type detonations were conducted at in July 1946 as part of to investigate the effect of nuclear weapons on warships. Able was detonated on 1 July 1946. The more spectacular Baker was detonated underwater on 25 July 1946. After the bombings at Hiroshima and Nagasaki, a number of Manhattan Project physicists founded the , which began as an emergency action undertaken by scientists who saw urgent need for an immediate educational program about atomic weapons. In the face of the destructiveness of the new weapons and in anticipation of the several project members including Bohr, Bush and Conant expressed the view that it was necessary to reach agreement on international control of nuclear research and atomic weapons. The , unveiled in a speech to the newly formed UNAEC in June 1946, proposed the establishment of an international atomic development authority, but was not adopted. Following a domestic debate over the permanent management of the nuclear program, the AEC was created by the to take over the functions and assets of the Manhattan Project. It established civilian control over atomic development, and separated the development, production and control of atomic weapons from the military. Military aspects were taken over by the AFSWP. Although the Manhattan Project ceased to exist on 31 December 1946, the Manhattan District was not abolished until 15 August 1947. Over 90% of the cost was for building plants and producing the fissionable materials, and less than 10% for development and production of the weapons. By comparison, the project's total cost by the end of 1945 was about 90% of the total spent on the production of US small arms not including ammunition and 34% of the total spent on US tanks during the same period. Overall, it was the second most expensive weapons project undertaken by the United States in World War II, behind only the design and production of the Boeing B-29 Superfortress. See also: The political and cultural impacts of the development of nuclear weapons were profound and far-reaching. In 1943 and 1944 he unsuccessfully attempted to persuade the Office of Censorship to permit writing about the explosive potential of uranium, and government officials felt that he had earned the right to report on the biggest secret of the war. Laurence witnessed both the Trinity test and the bombing of Nagasaki and wrote the official press releases prepared for them. He went on to write a series of articles extolling the virtues of the new weapon. His reporting before and after the bombings helped to spur public awareness of the potential of nuclear technology and motivated its development in the United States and the Soviet Union. The LOOW near became a principal repository for Manhattan Project waste for the Eastern United States. The wartime Manhattan Project left a legacy in the form of the network of : the , , , , and. Two more were established by Groves soon after the war, the at , and the at Albuquerque, New Mexico. They would be in the vanguard of the kind of large-scale research that , the director of the Oak Ridge National Laboratory, would call. The Naval Research Laboratory had long been interested in the prospect of using nuclear power for warship propulsion, and sought to create its own nuclear project. In May 1946, Nimitz, now , decided that the Navy should instead work with the Manhattan Project. A group of naval officers were assigned to Oak Ridge, the most senior of whom was Captain , who became assistant director there. They immersed themselves in the study of nuclear energy, laying the foundations for a. A similar group of Air Force personnel arrived at Oak Ridge in September 1946 with the aim of developing. Their NEPA project ran into formidable technical difficulties, and was ultimately cancelled. The ability of the new reactors to create radioactive isotopes in previously unheard-of quantities sparked a revolution in in the immediate postwar years. Starting in mid-1946, Oak Ridge began distributing radioisotopes to hospitals and universities. Most of the orders were for and , which were used in the diagnosis and treatment of cancer. In addition to medicine, isotopes were also used in biological, industrial and agricultural research. On handing over control to the Atomic Energy Commission, Groves bid farewell to the people who had worked on the Manhattan Project: Five years ago, the idea of Atomic Power was only a dream. You have made that dream a reality. You have seized upon the most nebulous of ideas and translated them into actualities. You have built cities where none were known before. You have constructed industrial plants of a magnitude and to a precision heretofore deemed impossible. You built the weapon which ended the War and thereby saved countless American lives. With regard to peacetime applications, you have raised the curtain on vistas of a new world. In 2014, the passed a law providing for a national park dedicated to the history of the Manhattan Project. The was established on 10 November 2015. Dudley, who got the idea from a report by of an interview she had with in 1959. The worry was not entirely extinguished in some people's minds until the. Retrieved 5 January 2018. United States figures follow the Measuring Worth series. Retrieved 28 June 2011. Los Alamos National Laboratory. Retrieved 23 November 2008. Retrieved 27 October 2010. Retrieved 16 March 2011. Los Alamos Science 7 : 186—189. Archived from on 25 August 2009. Retrieved 9 March 2010. Archived from on 6 September 2015. Retrieved 7 September 2015. Los Alamos National Laboratory. Retrieved 6 April 2011. Los Alamos National Laboratory. Retrieved 6 April 2011. Archived from PDF on 26 October 2014. Retrieved 3 December 2012. Officeof PublicAffairs, ArgonneNational Laboratory. Retrieved 23 March 2013. Retrieved 23 March 2013. Argonne National Laboratory; U. 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Archived from PDF on 23 February 2017. The New York Times. Retrieved 2 August 2015. Retrieved 10 November 2015. In the literature, the quote usually appears in the form shatterer of worlds, because this was the form in which it first appeared in print, in on November 8, 1948. It later appeared in Robert Jungk's Brighter than a Thousand Suns: A Personal History of the Atomic Scientists 1958 , which was based on an interview with Oppenheimer. The Western Political Quarterly. The Silverplate Bombers: A History and Registry of the Enola Gay and Other B-29s Configured to Carry Atomic Bombs. Retrieved 25 August 2013. Longing for the Bomb: Oak Ridge and Atomic Nostalgia. Chapel Hill, NC: University of North Carolina Press. Bulletin of the Atomic Scientists. Educational Foundation for Nuclear Science. Miamisburg, Ohio: Mound Laboratory, Atomic Energy Commission. Retrieved 31 October 2014. The Manhattan Project: Making the Atomic Bomb. 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Steam, obtained from the nearby K-25 powerhouse at a pressure of 1,000 pounds per square inch 6,900 kPa and temperature of 545 °F 285 °Cflowed downward through the innermost 1. Conant; andan civil to Stimson and president of. Little Boy and Fat Man bombs were used a month later in therespectively. On 5 February 1945, Matthias hand-delivered the first shipment of 80 g of 95%-pure plutonium nitrate to a Los Alamos courier in Los Angeles. Three more hemispheres followed on 23 Xi and were delivered three days later. Electromagnetic separation Main article: Electromagnetic isotope separation was developed by Lawrence at the University of California Radiation Laboratory. All but Joachimstal were in allied hands. He went on to write a series of articles extolling the virtues of the new weapon. oppenheimer single k kit

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