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10,000 | From measurements of 15 temples, 18 monumental tombs, 8 sarcophagi, and 58 grave stelae from the fifth century BC to the second century AD, one researcher concluded that the golden ratio was totally absent from Greek architecture of the classical fifth century BC, and almost absent during the following six centuries. | https://en.wikipedia.org/wiki?curid=12386 |
10,001 | Later sources like Vitruvius (first century BC) exclusively discuss proportions that can be expressed in whole numbers, i.e. commensurate as opposed to irrational proportions. | https://en.wikipedia.org/wiki?curid=12386 |
10,002 | The Section d'Or ('Golden Section') was a collective of painters, sculptors, poets and critics associated with Cubism and Orphism. Active from 1911 to around 1914, they adopted the name both to highlight that Cubism represented the continuation of a grand tradition, rather than being an isolated movement, and in homage... | https://en.wikipedia.org/wiki?curid=12386 |
10,003 | Piet Mondrian has been said to have used the golden section extensively in his geometrical paintings, though other experts (including critic Yve-Alain Bois) have discredited these claims. | https://en.wikipedia.org/wiki?curid=12386 |
10,004 | The Manhattan Project was a research and development undertaking during World War II that produced the first nuclear weapons. 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 Major General Leslie Groves of the U.S. Army Corps of... | https://en.wikipedia.org/wiki?curid=19603 |
10,005 | The project led to the development of two types of atomic bombs, both developed concurrently, during the war: a relatively simple gun-type fission weapon and a more complex implosion-type nuclear weapon. The Thin Man gun-type design proved impractical to use with plutonium, so a simpler gun-type called Little Boy was d... | https://en.wikipedia.org/wiki?curid=19603 |
10,006 | In parallel with the work on uranium was an effort to produce plutonium, which researchers at the University of California, Berkeley, discovered in 1940. After the feasibility of the world's first artificial nuclear reactor, the Chicago Pile-1, was demonstrated in 1942 at the Metallurgical Laboratory in the University ... | https://en.wikipedia.org/wiki?curid=19603 |
10,007 | The project was also charged with gathering intelligence on the German nuclear weapon project. Through Operation Alsos, 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... | https://en.wikipedia.org/wiki?curid=19603 |
10,008 | The first nuclear device ever detonated was an implosion-type bomb during the Trinity test, conducted at New Mexico's Alamogordo Bombing and Gunnery Range on 16 July 1945. Little Boy and Fat Man bombs were used a month later in the atomic bombings of Hiroshima and Nagasaki, respectively, with Manhattan Project personne... | https://en.wikipedia.org/wiki?curid=19603 |
10,009 | The discovery of nuclear fission by German chemists Otto Hahn and Fritz Strassmann in 1938, and its theoretical explanation by Lise Meitner and Otto Frisch, made the development of an atomic bomb a theoretical possibility. There were fears that a German atomic bomb project would develop one first, especially among scie... | https://en.wikipedia.org/wiki?curid=19603 |
10,010 | In February 1940, the U.S. Navy awarded Columbia University $6,000 in funding, most of which Enrico Fermi and Szilard spent on purchasing graphite. A team of Columbia professors including Fermi, Szilard, Eugene T. Booth and John Dunning created the first nuclear fission reaction in the Americas, verifying the work of H... | https://en.wikipedia.org/wiki?curid=19603 |
10,011 | In Britain, Frisch and Rudolf Peierls at the University of Birmingham had made a breakthrough investigating the critical mass of uranium-235 in June 1939. Their calculations indicated that it was within an order of magnitude of , which was small enough to be carried by a bomber of the day. Their March 1940 Frisch–Peier... | https://en.wikipedia.org/wiki?curid=19603 |
10,012 | As part of the scientific exchange, the MAUD Committee's findings were conveyed to the United States. One of its members, the Australian physicist Mark Oliphant, 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 s... | https://en.wikipedia.org/wiki?curid=19603 |
10,013 | On 9 October 1941, President Roosevelt approved the atomic program after he convened a meeting with Vannevar Bush and Vice President Henry A. Wallace. To control the program, he created a Top Policy Group consisting of himself—although he never attended a meeting—Wallace, Bush, Conant, Secretary of War Henry L. Stimson... | https://en.wikipedia.org/wiki?curid=19603 |
10,014 | The S-1 Committee held its meeting on 18 December 1941 "pervaded by an atmosphere of enthusiasm and urgency" in the wake of the attack on Pearl Harbor and the subsequent United States declaration of war upon Japan and then on Germany. Work was proceeding on three different techniques for isotope separation to separate ... | https://en.wikipedia.org/wiki?curid=19603 |
10,015 | 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 from Columbia, California and Princeton University to join his team at the University of Chicago, wher... | https://en.wikipedia.org/wiki?curid=19603 |
10,016 | Compton asked theoretical physicist J. Robert Oppenheimer of the University of California 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. John H. Manley,... | https://en.wikipedia.org/wiki?curid=19603 |
10,017 | 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 Glenn Seaborg and his team. The scientists at the (July 1942) Berkeley conference envisioned creating plutonium in nuclear reactors ... | https://en.wikipedia.org/wiki?curid=19603 |
10,018 | Considering the idea of the fission bomb theoretically settled—at least until more experimental data was available—the 1942 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 th... | https://en.wikipedia.org/wiki?curid=19603 |
10,019 | 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, where he could draw on administra... | https://en.wikipedia.org/wiki?curid=19603 |
10,020 | 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 Groves. Reybold, Somervell, and Styer decided to call the project "Development of Substitute Materials", but Grove... | https://en.wikipedia.org/wiki?curid=19603 |
10,021 | Marshall later conceded that, "I had 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. Nor were they impressed with estimates to the nearest order of ma... | https://en.wikipedia.org/wiki?curid=19603 |
10,022 | 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 an... | https://en.wikipedia.org/wiki?curid=19603 |
10,023 | Vannevar 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 leadershi... | https://en.wikipedia.org/wiki?curid=19603 |
10,024 | 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. Groves' orders placed ... | https://en.wikipedia.org/wiki?curid=19603 |
10,025 | 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. Groves promised not to use the AAA rating unless it was neces... | https://en.wikipedia.org/wiki?curid=19603 |
10,026 | 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, or Compton, but they could not be spared. Compton recommended Oppenheimer, who was already intimately familiar with the bomb desig... | https://en.wikipedia.org/wiki?curid=19603 |
10,027 | 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 Tube Alloys, because it was reluctant to share its technological lead and help the United States develop its... | https://en.wikipedia.org/wiki?curid=19603 |
10,028 | 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 ... | https://en.wikipedia.org/wiki?curid=19603 |
10,029 | 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 t... | https://en.wikipedia.org/wiki?curid=19603 |
10,030 | By March 1943 Conant decided that British help would benefit some areas of the project. James Chadwick and one or two other British scientists were important enough that the bomb design team at Los Alamos needed them, despite the risk of revealing weapon design secrets. In August 1943 Churchill and Roosevelt negotiated... | https://en.wikipedia.org/wiki?curid=19603 |
10,031 | When cooperation resumed after the Quebec agreement, the Americans' progress and expenditures amazed the British. The United States had already spent more than $1 billion ($ billion today), while in 1943, the United Kingdom had spent about £0.5 million. Chadwick thus pressed for British involvement in the Manhattan Pro... | https://en.wikipedia.org/wiki?curid=19603 |
10,032 | 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. The Belgian Congo and Canada held much of the world's uranium outside Eastern Europe, and the Belgian government in exile was in London. Britain a... | https://en.wikipedia.org/wiki?curid=19603 |
10,033 | 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 also said that Churchill was "the best friend the atomic bomb project had [as] he kept Roosevelt's interest up ... He just stir... | https://en.wikipedia.org/wiki?curid=19603 |
10,034 | The British wartime participation was crucial to the success of the United Kingdom's independent nuclear weapons program after the war when the McMahon Act of 1946 temporarily ended American nuclear cooperation. | https://en.wikipedia.org/wiki?curid=19603 |
10,035 | 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. On 29 September 1942, United States Under Secretary of War Robert P. Patterson authorized the Corps of Engineers to acquire of land by eminent domain at a cost of ... | https://en.wikipedia.org/wiki?curid=19603 |
10,036 | Initially known as the Kingston Demolition Range, the site was officially renamed the Clinton Engineer Works (CEW) in early 1943. While Stone & Webster concentrated on the production facilities, the architectural and engineering firm Skidmore, Owings & Merrill designed and built a residential community for 13,000. The ... | https://en.wikipedia.org/wiki?curid=19603 |
10,037 | Fine-arts photographer, Josephine Herrick, and her colleague, Mary Steers, helped document the work at Oak Ridge. | https://en.wikipedia.org/wiki?curid=19603 |
10,038 | 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 Albuquerque, New Mexico, where Oppenheimer owned a ranch. In October 1942, Major John H. Dudle... | https://en.wikipedia.org/wiki?curid=19603 |
10,039 | Patterson approved the acquisition of the site on 25 November 1942, authorizing $440,000 for the purchase of the site of , all but of which were already owned by the Federal Government. Secretary of Agriculture Claude R. Wickard granted use of some of United States Forest Service land to the War Department "for so long... | https://en.wikipedia.org/wiki?curid=19603 |
10,040 | Because it was secret, Los Alamos was referred to as "Site Y" or "the Hill". 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 Arm... | https://en.wikipedia.org/wiki?curid=19603 |
10,041 | An Army-OSRD council on 25 June 1942 decided to build a pilot plant for plutonium production in Red Gate Woods southwest of Chicago. In July, Nichols arranged for a lease of from the Cook County Forest Preserve District, and Captain James F. Grafton (1908-1969) was appointed Chicago area engineer. It soon became appare... | https://en.wikipedia.org/wiki?curid=19603 |
10,042 | Delays in establishing the plant in Red Gate Woods led Compton to authorize the Metallurgical Laboratory to construct the first nuclear reactor beneath the bleachers of Stagg Field at the University of Chicago. The reactor required an enormous amount of graphite blocks and uranium pellets. At the time, there was a limi... | https://en.wikipedia.org/wiki?curid=19603 |
10,043 | In January 1943, Grafton's successor, Major Arthur V. 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, Chicago Pile-3, the first heavy water reactor, went critical on 15 May 1944. ... | https://en.wikipedia.org/wiki?curid=19603 |
10,044 | 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 DuPont in November 1942 to be the prime contractor for the construction of the plutonium production complex. DuPont was offered a standard c... | https://en.wikipedia.org/wiki?curid=19603 |
10,045 | DuPont recommended that the site be located far from the existing uranium production facility at Oak Ridge. In December 1942, Groves dispatched Colonel Franklin Matthias and DuPont engineers to scout potential sites. Matthias reported that Hanford Site near Richland, Washington, was "ideal in virtually all respects". I... | https://en.wikipedia.org/wiki?curid=19603 |
10,046 | Under Secretary Patterson gave his approval on 9 February, allocating $5 million for the acquisition of of land in the area. The federal government relocated some 1,500 residents of White Bluffs and Hanford, and nearby settlements, as well as the Wanapum and other tribes using the area. A dispute arose with farmers ove... | https://en.wikipedia.org/wiki?curid=19603 |
10,047 | 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 1... | https://en.wikipedia.org/wiki?curid=19603 |
10,048 | Cominco had produced electrolytic hydrogen at Trail, British Columbia, since 1930. Urey suggested in 1941 that it could produce heavy water. To the existing $10 million plant consisting of 3,215 cells consuming 75 MW of hydroelectric power, secondary electrolysis cells were added to increase the deuterium concentration... | https://en.wikipedia.org/wiki?curid=19603 |
10,049 | The Chalk River, Ontario, site was established to rehouse the Allied effort at the Montreal Laboratory away from an urban area. A new community was built at Deep River, Ontario, to provide residences and facilities for the team members. The site was chosen for its proximity to the industrial manufacturing area of Ontar... | https://en.wikipedia.org/wiki?curid=19603 |
10,050 | 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 of heavy water would be re... | https://en.wikipedia.org/wiki?curid=19603 |
10,051 | 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 Joachimsthal in Czechoslovakia, and i... | https://en.wikipedia.org/wiki?curid=19603 |
10,052 | 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 Shinkolobwe mine in the Belgian Congo, but it was flooded... | https://en.wikipedia.org/wiki?curid=19603 |
10,053 | Mallinckrodt Incorporated in St. Louis, Missouri, took the raw ore and dissolved it in nitric acid to produce uranyl nitrate. Ether was then added in a liquid–liquid extraction process to separate the impurities from the uranyl nitrate. This was then heated to form uranium trioxide, which was reduced to highly pure ura... | https://en.wikipedia.org/wiki?curid=19603 |
10,054 | Natural uranium consists of 99.3% uranium-238 and 0.7% uranium-235, but only the latter is fissile. The chemically identical uranium-235 has to be physically separated from the more plentiful isotope. Various methods were considered for uranium enrichment, most of which was carried out at Oak Ridge. | https://en.wikipedia.org/wiki?curid=19603 |
10,055 | 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. | https://en.wikipedia.org/wiki?curid=19603 |
10,056 | The centrifuge process was regarded as the only promising separation method in April 1942. Jesse Beams had developed such a process at the University of Virginia during the 1930s, but had encountered technical difficulties. The process required high rotational speeds, but at certain speeds harmonic vibrations developed... | https://en.wikipedia.org/wiki?curid=19603 |
10,057 | Scaling this up to a production plant presented a formidable technical challenge. Urey and Cohen estimated that producing a kilogram (2.2 lb) of uranium-235 per day would require up to 50,000 centrifuges with rotors, or 10,000 centrifuges with rotors, assuming that 4-meter rotors could be built. The prospect of keeping... | https://en.wikipedia.org/wiki?curid=19603 |
10,058 | Although the centrifuge method was abandoned by the Manhattan Project, research into it advanced significantly after the war with the introduction of the Zippe-type centrifuge, which was developed in the Soviet Union by Soviet and captured German engineers. It eventually became the preferred method of Uranium isotope s... | https://en.wikipedia.org/wiki?curid=19603 |
10,059 | Electromagnetic isotope separation was developed by Lawrence at the University of California Radiation Laboratory. This method employed devices known as calutrons, a hybrid of the standard laboratory mass spectrometer and the cyclotron magnet. The name was derived from the words "California", "university" and "cyclotro... | https://en.wikipedia.org/wiki?curid=19603 |
10,060 | Marshall and Nichols discovered that the electromagnetic isotope separation process would require 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 Under Secretary of the Treasury Daniel W. Bell and asked for the transfer of 6,0... | https://en.wikipedia.org/wiki?curid=19603 |
10,061 | The silver bars were cast into cylindrical billets and taken to Phelps Dodge in Bayway, New Jersey, where they were extruded into strips thick, wide and long. These were wound onto magnetic coils by Allis-Chalmers in Milwaukee, Wisconsin. After the war, all the machinery was dismantled and cleaned and the floorboards b... | https://en.wikipedia.org/wiki?curid=19603 |
10,062 | Responsibility for the design and construction of the electromagnetic separation plant, which came to be called Y-12, was assigned to Stone & Webster by the S-1 Committee in June 1942. The design called for five first-stage processing units, known as Alpha racetracks, and two units for final processing, known as Beta r... | https://en.wikipedia.org/wiki?curid=19603 |
10,063 | 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, an... | https://en.wikipedia.org/wiki?curid=19603 |
10,064 | Tennessee Eastman was contracted to manage Y-12 on the usual cost plus fixed-fee basis, with a fee of $22,500 per month plus $7,500 per racetrack for the first seven racetracks and $4,000 per additional racetrack. The calutrons were initially operated by scientists from Berkeley to remove bugs and achieve a reasonable ... | https://en.wikipedia.org/wiki?curid=19603 |
10,065 | Y-12 initially enriched the uranium-235 content to between 13% and 15%, and shipped the first few hundred grams of this to Los Alamos in March 1944. 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 p... | https://en.wikipedia.org/wiki?curid=19603 |
10,066 | The most promising but also the most challenging method of isotope separation was gaseous diffusion. Graham's law states that the rate of effusion of a gas is inversely proportional to the square root of its molecular mass, so in a box containing a semi-permeable membrane and a mixture of two gases, the lighter molecul... | https://en.wikipedia.org/wiki?curid=19603 |
10,067 | In November 1942 the Military Policy Committee approved the construction of a 600-stage gaseous diffusion plant. On 14 December, M. W. Kellogg accepted an offer to construct the plant, which was codenamed K-25. A cost plus fixed-fee contract was negotiated, eventually totaling $2.5 million. A separate corporate entity ... | https://en.wikipedia.org/wiki?curid=19603 |
10,068 | Kellex's design for K-25 called for a four-story long U-shaped structure containing 54 contiguous buildings. 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... | https://en.wikipedia.org/wiki?curid=19603 |
10,069 | 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 1.1% enrichment and the output of the S-50 thermal diffusion plant began being used as feed. Some product produced the next month reached nearly 7... | https://en.wikipedia.org/wiki?curid=19603 |
10,070 | The thermal diffusion process was based on Sydney Chapman and David Enskog's theory, 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... | https://en.wikipedia.org/wiki?curid=19603 |
10,071 | 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 Captain William S. Parsons, the naval officer in charge of ordnance development at Los Alamos, brought Oppenheimer news of encouraging progress in the Nav... | https://en.wikipedia.org/wiki?curid=19603 |
10,072 | Groves contracted with the H. K. Ferguson Company of Cleveland, Ohio, to build the thermal diffusion plant, which was designated S-50. Groves's advisers, Karl Cohen and W. I. Thompson from Standard Oil, estimated that it would take six months to build. Groves gave Ferguson just four. Plans called for the installation o... | https://en.wikipedia.org/wiki?curid=19603 |
10,073 | 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 of 0.852% uranium-235 in October. Leaks limited production and forced shutdowns over the next few months, but in June 1945 it produced . By March 1945... | https://en.wikipedia.org/wiki?curid=19603 |
10,074 | About 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 Little Boy. | https://en.wikipedia.org/wiki?curid=19603 |
10,075 | 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 transmuted into u... | https://en.wikipedia.org/wiki?curid=19603 |
10,076 | In March 1943, DuPont began construction of a plutonium plant on a site at Oak Ridge. Intended as a pilot plant for the larger production facilities at Hanford, it included the air-cooled X-10 Graphite Reactor, a chemical separation plant, and support facilities. Because of the subsequent decision to construct water-co... | https://en.wikipedia.org/wiki?curid=19603 |
10,077 | 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 hot dipping process without success.... | https://en.wikipedia.org/wiki?curid=19603 |
10,078 | Watched by Fermi and Compton, the X-10 Graphite Reactor went critical on 4 November 1943 with about of uranium. A week later the load was increased to , 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 ... | https://en.wikipedia.org/wiki?curid=19603 |
10,079 | 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... | https://en.wikipedia.org/wiki?curid=19603 |
10,080 | As at Oak Ridge, the most difficulty was encountered while canning the uranium slugs, which commenced at Hanford in March 1944. They were pickled to remove dirt and impurities, dipped in molten bronze, tin, and aluminum-silicon alloy, canned using hydraulic presses, and then capped using arc welding under an argon atmo... | https://en.wikipedia.org/wiki?curid=19603 |
10,081 | 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 P... | https://en.wikipedia.org/wiki?curid=19603 |
10,082 | Construction of the reactor itself commenced in February 1944. Watched by Compton, Matthias, DuPont's Crawford Greenewalt, Leona Woods 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 a... | https://en.wikipedia.org/wiki?curid=19603 |
10,083 | Fermi contacted Chien-Shiung Wu, who identified the cause of the problem as neutron poisoning from xenon-135, which has a half-life of 9.2 hours. Fermi, Woods, Donald J. Hughes and John Archibald Wheeler then calculated the nuclear cross section of xenon-135, which turned out to be 30,000 times that of uranium. DuPont ... | https://en.wikipedia.org/wiki?curid=19603 |
10,084 | 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 lanthanum fluoride process for separa... | https://en.wikipedia.org/wiki?curid=19603 |
10,085 | 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 thi... | https://en.wikipedia.org/wiki?curid=19603 |
10,086 | 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. Not... | https://en.wikipedia.org/wiki?curid=19603 |
10,087 | 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. Each separation plant consisted of four buildings: a process cell building or "canyon" (known as ... | https://en.wikipedia.org/wiki?curid=19603 |
10,088 | 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, some... | https://en.wikipedia.org/wiki?curid=19603 |
10,089 | In 1943, development efforts were directed to a gun-type fission weapon with plutonium called Thin Man. 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 plu... | https://en.wikipedia.org/wiki?curid=19603 |
10,090 | This made reactor plutonium unsuitable for use in a gun-type weapon. The plutonium-240 would start the chain reaction too quickly, causing a predetonation that would release enough energy to disperse the critical mass with a minimal amount of plutonium reacted (a fizzle). A faster gun was suggested but found to be impr... | https://en.wikipedia.org/wiki?curid=19603 |
10,091 | Work on an alternative method of bomb design, known as implosion, had begun earlier under the direction of the physicist Seth Neddermeyer. 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 ca... | https://en.wikipedia.org/wiki?curid=19603 |
10,092 | 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 Fat Man, began in August 1944 when Oppenheimer implemented a sweeping reorganization of the Los Alamos laboratory to focus on implosion. Two new groups w... | https://en.wikipedia.org/wiki?curid=19603 |
10,093 | 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 composition B as the fast explosive and baratol as the slow explosive. The final design resembled a soccer ball, with 20 hexagonal and 12 pentagonal ... | https://en.wikipedia.org/wiki?curid=19603 |
10,094 | To study the behavior of converging shock waves, Robert Serber devised the RaLa Experiment, which used the short-lived radioisotope lanthanum-140, a potent source of gamma radiation. 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 ioniz... | https://en.wikipedia.org/wiki?curid=19603 |
10,095 | Within the explosives was the thick aluminum pusher, which provided a smooth transition from the relatively low density explosive to the next layer, the thick tamper of natural uranium. 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 p... | https://en.wikipedia.org/wiki?curid=19603 |
10,096 | 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 allotropes o... | https://en.wikipedia.org/wiki?curid=19603 |
10,097 | 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 contam... | https://en.wikipedia.org/wiki?curid=19603 |
10,098 | 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. Consideration was therefore given to a controlled fizzle, but Oppenheimer opted instead for a f... | https://en.wikipedia.org/wiki?curid=19603 |
10,099 | In March 1944, planning for the test was assigned to Kenneth Bainbridge, a professor of physics at Harvard, working under Kistiakowsky. Bainbridge selected the bombing range near Alamogordo Army Airfield as the site for the test. Bainbridge worked with Captain Samuel P. Davalos on the construction of the Trinity Base C... | https://en.wikipedia.org/wiki?curid=19603 |
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