Clinton Engineer Works
The Clinton Engineer Works (CEW) was the name of the Manhattan Project's production facility during World War II that produced the enriched uranium used in the Little Boy atomic bomb dropped on Hiroshima in August 1945. The secret semiworks was on Oak Ridge in the eastern part of the Tennessee, about 18 miles (29 km) west of Knoxville, and was named after the town of Clinton, Tennessee, 8 miles (13 km) to the north. The plants are mainly in Roane County although the northern part of the site in Anderson County. The Manhattan District Engineer. Kenneth Nichols, moved the Manhattan District headquarters from Manhattan to Oak Ridge in August 1943.
Construction workers were housed in a community known as Happy Valley. Built by the Army in 1943, the temporary Happy Valley community housed 15,000 people in trailer homes. The town of Oak Ridge was established to house the production staff. The operating force peaked at 50,000 workers just after the end of the war. The construction labour force peaked at 75,000 and the combined employment peak was 80,000. Developed by the federal government as a segregated community, black residents lived only in an area known as Gamble Valley, in government-built hutments (one-room shacks) on the south side of what is now Tuskegee Drive.
On 25 June 1942, the Office of Scientific Research and Development (OSRD) S-1 Executive Committee deliberated on where the production facilities of the Manhattan Project should be located. Brigadier General Wilhelm D. Styer recommended that all the different manufacturing facilities be built at the same site in order to simplify security and construction. Such a site would require a substantial tract of land to accommodate both the facilities and housing for the thousands of workers. The plutonium processing plant needed to be 2 to 4 miles (3.2 to 6.4 km) from the site boundary and any other installation in case radioactive fission products escaped. While security and safety concerns suggested a remote site, it still needed to be near sources of labor, and accessible by road and rail transportation. A mild climate that allow construction to proceed throughout the year was desirable. Terrain separated by ridges would reduce the impact of accidental explosions, but they could not be so steep as to complicate construction. The substratum needed to be firm enough to provide good foundations, but not so rocky that it would hinder excavation work. It was estimated that the proposed plants would need access to 150,000 KW of electricity and 370,000 US gallons (1,400,000 l; 310,000 imp gal) of water per minute. A War Department policy was that as a rule munitions facilities should not be located west of the Sierra or Cascade Ranges, east of the Appalachian Mountains, or within 200 miles (320 km) of the Canadian or Mexican borders.
Several sites were considered in the Tennessee Valley, two in the Chicago area, one near the Shasta Dam in California, and some in Washington state, where some facilities were eventually established. An OSRD team had selected the Knoxville, Tennessee, area in April 1942, and in May Arthur Compton, the director of the Metallurgical Laboratory had met with Gordon R. Clapp, the General Manager of the Tennessee Valley Authority (TVA). The Chief Engineer of the Manhattan District (MED), Colonel James C. Marshall, asked Colonel Leslie R. Groves, Jr. to undertake a study within the Army's Office of the Chief of Engineers. After receiving assurances that the TVA could supply the required quantity of electric power if given priority for procuring some needed equipment, Groves also concluded that the Knoxville area was suitable. The only voice of dissent at 25 June meeting was Ernest O. Lawrence, who wanted the electromagnetic separation plant located much nearer to his Radiation Laboratory in California. The Shasta Dam area remained under consideration for the electromagnetic plant until September, by which time Lawrence had dropped his objection.
On 1 July, Marshall and his deputy, Lieutenant Colonel Kenneth Nichols, surveyed sites in the Knoxville area with representatives of the TVA and Stone & Webster, the designated construction contractor. No perfectly suitable site was found, and Marshall even ordered another survey of the Spokane, Washington, area. At the time, the proposed nuclear reactor, gas centrifuge and gaseous diffusion technologies were still in the research stage, and the design of the plant was a long way off. The schedules, which called for construction work on the nuclear reactor to commence by 1 October 1942, the electromagnetic plant by 1 November, the centrifugal plant by 1 January 1943 and the gaseous diffusion plant by 1 March 1943, were quite unrealistic. While work could not commence on the plants, a start could be made on the housing and administrative buildings. Stone & Webster therefore drew up a detailed report on the most promising site, about 12 miles (19 km) west of Knoxville.
This portion of the quiet rural area was called Black Oak Ridge and was the northernmost of five principal oak- and pine-covered ridges around the meandering Clinch River. It was a verdant, beautiful countryside with rolling hills covered with dogwood and full of partridge and deer. To the east were the Great Smoky Mountains, to the west the peaks of the Cumberland Mountains.
The site was located in Roane County and Anderson County, and lay roughly halfway between the two county seats of Kingston and Clinton. Its major drawback was that a major road, Tennessee State Route 61 ran through it. Stone & Webster considered the possibility of re-routing the road. The Ohio River Division (ORD) of the Corps of Engineers estimated that it would cost $4.25 million (equivalent to $61.34 million in 2015) to purchase the entire 83,000 acres (34,000 ha) site.
Groves became the director of the Manhattan Project on 23 September, with the rank of brigadier general. That afternoon, he took a train to Knoxville, where he met with Marshall. After touring the site, Groves concluded that the site "was an even better choice than I had anticipated." He called Colonel John J. O'Brien of the Corps of Engineers' Real Estate Branch, and told him to proceed with acquiring the land. The site was initially known as the Kingston Demolition Range. It officially became the Clinton Engineer Works (CEW) in January 1943. It was given the codename of Site X. After the town site of Oak Ridge was established in mid-1943, this name became its postal address; but the site was not officially renamed Oak Ridge until 1947.
War Department policy was that land should be acquired by direct purchase; but as time was short, it was decided to proceed immediately with condemnation. This allowed access to the site for construction crews, provided faster compensation for the owners, and expedited the handling of property with defective titles. On 28 September 1942, the ORD Real Estate Branch opened a project office in Harriman with a staff of 54 surveyors, appraisers, lawyers and office workers. The ORD Real Estate Branch was quite busy at this time, as it was also acquiring land for the Dale Hollow Reservoir, so some staff were borrowed from the Federal Land Bank and the TVA. The next day, Under Secretary of War Robert P. Patterson authorized the acquisition of 56,000 acres (23,000 ha) at an estimated cost of $3.5 million (equivalent to $50.52 million in 2015). At the request of the ORD Real Estate Branch attorneys, the District Court for the Eastern District of Tennessee issued an order of possession on 6 October, effective the next day. Recognizing the hardship that it would cause to the landowners, it restricted immediate exclusive possession to properties "essential to full and complete development of the project".
Over 1,000 families lived on the site on farms or in the hamlets of Elza, Robertsville and Scarboro. The first that most heard about the acquisition was when a representative from the ORD showed up to inform them that their land was being acquired. Some returned home from work one day to find an eviction notice nailed to their door or to a tree in the yard. Most were given six weeks to leave, but some were given just two. The government took possession of 13 tracts for immediate construction work on 20 November 1942. By May 1943, 742 declarations had been filed covering 53,334 acres (21,584 ha). Most residents were told to prepare to leave between 1 December 1942 and 15 January 1943. In cases where this would cause undue hardship, the MED allowed residents to stay beyond this date. For some it was the third time that they had been evicted by the government, having previously been evicted for the Great Smoky Mountains National Park in the 1920s and the TVA's Norris Dam in the 1930s. Many expected that, like the TVA, the Army would provide assistance to help them relocate; but unlike the TVA, the Army had no mission to improve the area or the lot of the local people, and no funds for the purpose. Tires were in short supply in wartime America, and moving vehicles were hard to find. Some residents had to leave behind possessions that they were unable to take with them.
A delegation of landowners presented the ORD Real Estate Branch with a petition to protesting the acquisition of their property on 23 November 1942, and that night over 200 landowners held a meeting where they agreed to hire lawyers and appraisers to challenge the Federal government. Local newspapers and politicians were sympathetic to their cause. By the end of May 1943, agreements were reached covering 416 tracts totalling 21,742 acres (8,799 ha), but some landowners rejected the government's offers. The ORD Real Estate Branch invoked a procedure under Tennessee law that allowed for a jury of five citizens appointed by the Federal District Court to review the compensation offered. They handled five cases in which they proposed higher values than those of the ORD appraisers, but the landowners rejected them as well, so the Army discontinued the use of this method. In response to rising public criticism, O'Brien commissioned a review by the Department of Agriculture. It found that the appraisals had been fair and just, while farmers overestimated the size and productivity of their land.
The landowners turned to their local Congressman, John Jennings, Jr. On 1 February 1943, Jennings introduced a resolution in the House of Representatives calling for a committee to investigate the values offered to the landowners. He also complained to Patterson about how buildings and facilities were being demolished by the MED. On 9 July 1943, Andrew J. May, the chairman of the House Committee on Military Affairs, appointed an investigating subcommittee chaired by Clifford Davis, who selected Dewey Short and John Sparkman as its other members. Public hearings were held in Clinton on 11 August 1943, and in Kingston the following day. Its report, presented in December 1943, made a number of specific recommendations concerning the Corps of Engineers' land acquisition process, but neither Congress nor the War Department moved to provide any additional compensation for the landowners.
In July 1943, Groves prepared to issue Public Proclamation No. 2, declaring the site a military exclusion area. He asked Marshall to present it to the Governor of Tennessee, Prentice Cooper. Marshall, in turn, delegated the task to the area engineer, Major Thomas T. Crenshaw, who sent a junior officer, Captain George B. Leonard. Cooper was unimpressed. He told Leonard that had not been informed about the purpose of the CEW, that the Army had kicked the farmers off their land, and had not compensated the counties for the roads and bridges, which would now be closed. In his opinion it was a "an experiment in socialism", a New Deal project being undertaken in the name of the war effort. Instead of reading the proclamation, he tore it up and threw it in the waste paper basket. Marshall went to Nashville to apologize to Cooper, who refused to talk to him. Nichols, who succeeded Marshall as chief engineer of the Manhattan District, met Cooper on 31 July 1943, and offered compensation in the form of Federal financing for road improvements. Cooper accepted an offer from Nichols to visit the CEW, which he did on 3 November 1943.
Nichols and Cooper came to an agreement about the Solway Bridge. Although it was in Knox County, Anderson County had contributed $27,000 (equivalent to $390,000 in 2015) towards its construction. It was still paying off the bonds, but now the bridge was usable only by CEW workers. Nichols negotiated a deal by which Knox County was paid $25,000 annually (equivalent to $361,000 in 2015) for the bridge, of which $6,000 (equivalent to $87,000 in 2015) was to be used to maintain the access road. Judge Thomas L. Seeber then threatened to close the Edgemoor Bridge unless Anderson County was similarly compensated. An agreement was reached under which Anderson County received $10,000 (equivalent to $144,000 in 2015) for the bridge and $200 per month (equivalent to $3,000 in 2015). Knox County did not keep its side of the bargain. Heavy traffic tore up the road, and it failed after torrential rains in 1944. The Army was forced to spend $5,000 (equivalent to $72,000 in 2015) per month on road works in Knox County.
Additional parcels of land were acquired during 1943 and 1944 for access roads, a railway spur and security purposes. This brought the total amount acquired to about 58,900 acres (23,800 ha). The Harriman office closed on 10 June 1944, but reopened on 1 September 1944 to deal with the additional parcels. The last of the acquisitions was not complete until 1 March 1945. The final cost of the land acquired was around $2.6 million (equivalent to $37.53 million in 2015), about $47 an acre.
X-10 graphite reactor
In March 1943, DuPont began construction of a plutonium plant on a 112-acre (0.5 km2) site at Oak Ridge. Intended as a pilot plant for the larger production facilities at Hanford, it included the air-cooled graphite-moderated X-10 nuclear reactor, 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 nuclear graphite, 24 feet (7.3 m) long on each side, weighing around 1,500 long tons (1,500 t), surrounded by 7 feet (2.1 m) of high-density concrete as a radiation shield.
The X-10 Graphite Reactor went critical on 4 November 1943 with about 30 long tons (30 t) of uranium. A week later the load was increased to 36 long tons (37 t), raising its power generation to 500 kW, and by the end of the month the first 500 milligrams (0.018 oz) of plutonium was created. Modifications over time raised the power to 4,000 kW in July 1944. X-10 operated as a plutonium production plant until January 1945, when it was turned over to research activities.
Y-12 electromagnetic separation plant
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 cyclotron. The name was derived from the words "California", "university" and "cyclotron". In the electromagnetic separation process, a magnetic field deflected charged uranium 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.
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 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.
Tennessee Eastman was hired 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 operating rate. They were then turned over to trained Tennessee Eastman operators who had only a high school education. Nichols compared unit production data, and pointed out to Lawrence that the young "hillbilly" girl operators were outperforming his PhDs. They agreed to a production race and Lawrence lost, a morale boost for the Tennessee Eastman workers and supervisors. The girls were "trained like soldiers not to reason why", while "the scientists could not refrain from time-consuming investigation of the cause of even minor fluctuations of the dials."
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 production to 10% of the uranium-235 feed by January 1945. In February the Alpha racetracks began receiving slightly enriched (1.4%) feed from the new S-50 thermal diffusion plant. The next month it received enhanced (5%) feed from the K-25 gaseous diffusion plant. By April K-25 was producing uranium sufficiently enriched to feed directly into the Beta tracks.
Y-12 shut down in 1947, but is still in use for nuclear weapons processing and materials storage. A production facility for the hydrogen bomb exploded in Operation Castle in 1954 was hastily installed in 1952.
K-25 gaseous diffusion plant
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 molecules will pass out of the container more rapidly than the heavier molecules. 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, Karl P. Cohen and John R. Dunning.
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 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 Bell Telephone Laboratories and the Bakelite Corporation. In January 1944, Groves ordered the Kellex barrier into production.
Kellex's design for K-25 called for a four-story 0.5-mile (0.80 km) 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 as part of a single cascade. A survey party began construction by marking out the 500-acre (2.0 km2) site in May 1943. 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, Union Carbide and Carbon, on 11 September 1945. The total cost, including the K-27 plant completed after the war, came to $480 million.
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% 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. Uranium was enriched by the K-25 gaseous diffusion process until 1985, was subsequently decommissioned and decontaminated. A coal-fired power station (235 MVA) was included for reliability and to provide variable frequency, although most electric power came from the TVA.
S-50 liquid thermal diffusion plant
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 used as a means of isotope separation. This process was first demonstrated by H. Clusius and G. 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 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 who was 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 set up a committee consisting of Warren K. Lewis, Eger Murphree and Richard Tolman to investigate the idea, and they estimated that a thermal diffusion plant costing $3.5 million could enrich 50 kilograms (110 lb) of uranium per week to nearly 0.9% uranium-235. Groves approved its construction on 24 June 1944.
Groves contracted with the H. K. Ferguson Company of Cleveland, Ohio, to build the thermal diffusion plant, which was designated S-50. Groves' 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 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 100 pounds per square inch (690 kPa) and temperature of 545 °F (285 °C), flowed downward through the innermost 1.25-inch (32 mm) nickel pipe, while water at 155 °F (68 °C) flowed upward through the outermost iron pipe. 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 10.5 pounds (4.8 kg) of 0.852% uranium-235 in October. 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 0.71% to 0.89%. 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.
In early September Nichols appointed a production control committee, headed by A. V. (Pete) Peterson (a reserve officer, and his wife's sister's husband). Peterson’s staff tried various combinations, using mechanical calculating machines, and decided that the S-50 production should be fed to K-25 rather than Y-12, which was done in April 1945. The charts also showed that the proposed top stages for K-25 should be abandoned, as should Lawrence's recommendation to add more alpha stages to the Y-12 plant. Groves accepted their proposal to add more base units to the gaseous-diffusion plant (K-27 not K-25) and one more beta stage track for Y-12. These additions were estimated to cost $100 million, with completion in February 1946.
Because the enriched uranium was shipped out discreetly by courier in a suitcase, there was a local rumour that the secret CEW project must be a failure or a boondoggle. Many of the local residents and workers observed that thousands of railroad cars were carrying supplies into the CEW but no one had ever seen anything shipped out.
The S-50 liquid thermal diffusion plant was demolished soon after the war.
While Stone and Webster concentrated on the production facilities, the architectural and engineering firm Skidmore, Owings & Merrill designed and built a residential community for 13,000. The community was located on the slopes of Black Oak Ridge, from which the new town of Oak Ridge 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 Turner Construction Company through a subsidiary, the Roane-Anderson Company (for Roane and Anderson Counties, in which Oak Ridge was located). 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.
On 19 March 1949, the residential and commercial portion of Oak Ridge, known as the "townsite," was opened to public access, and access to the Atomic Energy Commission facilities was controlled by three gatehouses which replaced the seven wartime gates: Blair Gate to Harriman, Oliver Springs Gate, Elza Gate to Clinton, Edgemoor Gate to Clinton, Solway Gate to Knoxville, White Wing Gate to Lenoir City and Gallaher Gate to Kingston.
Other wartime facilities
- Oak Ridge High School (Oak Ridge, Tennessee) established 1943
- United Church, The Chapel on the Hill established 1943
- Oak Ridge Symphony Orchestra established 1944
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