Manhattan Project

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 Hahn and Strassmann.

He created a Top Policy Group consisting of himself—although he never attended a meeting—Wallace, Bush, Conant, Secretary of War Henry L. Stimson, and the Chief of Staff of the Army, General George C. Marshall.

[23] Arthur Compton asked theoretical physicist J. Robert Oppenheimer of the University of California to take over research into fast neutron calculations—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.

[28] To review this work and the general theory of fission reactions, Oppenheimer and Fermi convened meetings at the University of Chicago in June and at the University of California in July 1942 with theoretical physicists Hans Bethe, John Van Vleck, Edward Teller, Emil Konopinski, Robert Serber, Stan Frankel, and Eldred C. (Carlyle) Nelson, and experimental physicists Emilio Segrè, Felix Bloch, Franco Rasetti, Manley, and Edwin McMillan.

[30] They also explored designs involving spheroids, a primitive form of "implosion" suggested by Richard C. Tolman, and the possibility of autocatalytic methods to increase the efficiency of the bomb as it exploded.

Marshall created a liaison office in Washington, D.C., but established his temporary headquarters at 270 Broadway in New York, where he could draw on administrative support from the Corps of Engineers' North Atlantic Division.

[76] Groves later said that the British scientists' direct contributions to the Manhattan Project were "helpful but not vital," but "there probably would have been no atomic bomb to drop on Hiroshima" without Britain's (particularly Churchill's) impetus.

[79][80] On 29 September 1942, United States Under Secretary of War Robert P. Patterson authorized the Corps of Engineers to acquire 56,000 acres (23,000 ha) of land by eminent domain at a cost of $3.5 million.

[96] Secretary of Agriculture Claude R. Wickard granted about 45,000 acres (18,000 ha) of United States Forest Service land to the War Department "for so long as the military necessity continues".

In July, Nichols arranged for a lease of 1,025 acres (415 ha) from the Cook County Forest Preserve District, and Captain James F. Grafton was appointed Chicago area engineer.

[103][104] Delays in establishing the plant at Site A led Arthur Compton to authorize the Metallurgical Laboratory to construct the first nuclear reactor beneath the bleachers of Stagg Field at the University of Chicago.

"[109][e] In January 1943, Grafton's successor, Major Arthur V. Peterson, ordered Chicago Pile-1 dismantled and reassembled at the Site A in the forest preserve, as he regarded the operation of a reactor as too hazardous for a densely populated area.

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.

[119] 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 and guard dogs were less evident.

The prospect of keeping so many rotors operating continuously at high speed appeared daunting,[144] and when Beams ran his experimental apparatus, he obtained only 60% of the predicted yield, indicating that more centrifuges were required.

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 atmosphere.

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.

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 which was chosen for the pilot separation plant.

[224] The F-1 (Super) Group calculated that burning 1 cubic meter (35 cu ft) of liquid deuterium would release the energy of 10 megatonnes of TNT (42 PJ), enough to devastate 1,000 square miles (2,600 km2).

[232][233] Groves did not relish the prospect of explaining to a Senate committee the loss of a billion dollars worth of plutonium, so a cylindrical containment vessel codenamed "Jumbo" was constructed to recover the active material in the event of a failure.

This proved a daunting task given the amount of knowledge and speculation about nuclear fission that existed prior to the Manhattan Project, the huge numbers of people involved, and the scale of the facilities.

[259] In 1945 Life estimated that before the Hiroshima and Nagasaki bombings "probably no more than a few dozen men in the entire country knew the full meaning of the Manhattan Project, and perhaps only a thousand others even were aware that work on atoms was involved."

Warned that disclosing the project's secrets was punishable by 10 years in prison or a fine of US$10,000 (equivalent to $169,000 in 2023), they monitored "dials and switches while behind thick concrete walls mysterious reactions took place" without knowing the purpose of their jobs.

William L. Laurence of The New York Times, who wrote an article on atomic fission in The Saturday Evening Post of 7 September 1940, later learned that government officials asked librarians nationwide in 1943 to withdraw the issue.

Lieutenant Colonel Boris T. Pash, the head of the Counter Intelligence Branch of the Western Defense Command, investigated suspected Soviet espionage at the Radiation Laboratory in Berkeley.

[289] In April 1945, Pash, in command of a composite force known as T-Force, conducted Operation Harborage, a sweep behind enemy lines of Hechingen, Bisingen, and Haigerloch—the heart of the German nuclear effort.

[290][291] Alsos teams rounded up German scientists including Kurt Diebner, Otto Hahn, Walther Gerlach, Werner Heisenberg, and Carl Friedrich von Weizsäcker.

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.

As plans were made to turn the work over to the Army Corps of Engineers, Bush wrote to Roosevelt in late 1942 that "it would be ruinous to the essential secrecy to have to defend before an appropriations committee any request for funds for this project."

Issues of this kind resulted in Hanford becoming "one of the most contaminated nuclear waste sites in North America", and the subject of significant cleanup efforts after it was deactivated in the late Cold War.

Oval shaped shoulder patch with a deep blue background. At the top is a red circle and blue star, the patch of the Army Service Forces. It is surrounded by a white oval, representing a mushroom cloud. Below it is a white lightning bolt cracking a yellow circle, representing an atom.
Enrico Fermi , John R. Dunning , and Dana P. Mitchell in front of the cyclotron in the basement of Pupin Hall at Columbia University , 1940
Six men in suits sitting on chairs, smiling and laughing
March 1940 meeting at Berkeley, California: Ernest O. Lawrence , Arthur H. Compton , Vannevar Bush , James B. Conant , Karl T. Compton , and Alfred L. Loomis
A series of doodles
Different fission bomb assembly methods explored during the July 1942 conference
Organization chart of the project, showing project headquarters divisions at the top, Manhattan District in the middle, and field offices at the bottom
The Manhattan Project Organizational Chart, 1 May 1946
A man smiling in a suit in suit and one in a uniform chat around a pile of twisted metal.
Oppenheimer and Groves at the remains of the Trinity test 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. [ 48 ]
A large man in uniform and a bespectacled thin man in a suit and tie sit at a desk.
Groves confers with James Chadwick , the head of the British Mission.
Map of the United States and southern Canada with major project sites marked Berkeley, California Inyokern, California Richland, Washington Trail, British Columbia Wendover, Utah Monticello, Utah Uravan, Colorado Los Alamos, New Mexico Alamogordo, New Mexico Ames, Iowa St Louis, Missouri Chicago, Illinois Dana, Indiana Dayton, Ohio Sylacauga, Alabama Morgantown, West Virginia Oak Ridge, Tennessee Chalk River Laboratories Rochester, New York Washington, D.C.
A selection of US and Canadian sites important to the Manhattan Project. Research and production took place at more than thirty sites across the US, the UK, and Canada. Click on the location for more information.
Workers, mostly women, pour out of a cluster of buildings. A billboard exhorts them to "Make C.E.W. COUNT continue to protect project information!"
Shift change at the Y-12 uranium enrichment facility at the Clinton Engineer Works in Oak Ridge, Tennessee , on 11 August 1945. By May 1945, 82,000 people were employed at the Clinton Engineer Works. [ 78 ] Photograph by the Manhattan District photographer Ed Westcott .
Map of Los Alamos site, New Mexico, 1943–1945
Some of the University of Chicago team that worked on the Chicago Pile-1 , the first nuclear reactor, including Enrico Fermi and Walter Zinn in the front row and Harold Agnew , Leona Woods and Leó Szilárd in the second
A large crowd of sullen looking workmen at a counter where two women are writing. Some of the workmen are wearing identify photographs of themselves on their hats.
Hanford workers collect their paychecks at the Western Union office.
A sample of a high-quality uranium-bearing ore ( Tobernite ) from the Shinkolobwe mine in Belgian Congo
A uranium metal "biscuit" created from the reduction reaction of the Ames process
Contour map of the Oak Ridge area. There is a river to the south, while the township is in the north.
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.
A large oval-shaped structure
Alpha I racetrack at Y-12
A long corridor with many consoles with dials and switches, attended by women seated on high stools
The Calutron Girls were young women who monitored calutron control panels at Y-12. Gladys Owens, seated in the foreground, was unaware of what she had been involved in. [ 154 ]
Oblique aerial view of an enormous U-shaped building
Oak Ridge K-25 plant
A factory with three smoking chimneys on a river bend, viewed from above
The S-50 plant is the dark building to the upper left behind the Oak Ridge powerhouse (with smokestacks).
Two workmen on a movable platform similar to that used by window washers, stick a rod into one of many small holes in the wall in front of them.
Workers load uranium slugs into the X-10 Graphite Reactor.
An aerial view of the Hanford B-Reactor site from June 1944. At center is the reactor building. Small trucks dot the landscape and give a sense of scale. Two large water towers loom above the plant.
Aerial view of Hanford B-Reactor site, June 1944
A contour map showing the fork of the Columbia and Yakima rivers and the boundary of the land, with seven small red squares marked on it
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.
Long, tube-like casings. In the background are several ovoid casings and a tow truck.
A row of Thin Man casings. Fat Man casings are visible in the background.
Diagram showing fast explosive, slow explosive, uranium tamper, plutonium core and neutron initiator
An implosion-type nuclear bomb
A shack surrounded by pine trees. There is snow on the ground. A man and a woman in white lab coats are pulling on a rope, which is attached to a small trolley on a wooden platform. On top of the trolley is a large cylindrical object.
Remote handling of a kilocurie source of radiolanthanum for a RaLa Experiment at Los Alamos
Men stand around a large oil-rig type structure. A large round object is being hoisted up.
The explosives of "the gadget" were raised to the top of the tower for the final assembly.
The Trinity test of the Manhattan Project was the first detonation of a nuclear weapon .
Manhattan Project contractors' employment, August 1942-December 1946
A large crowd of men and women in uniform listens to a fat man in uniform speaking at a microphone. They are wearing the Army Service Forces sleeve patch. The women are at the front and the men at the back. Beside him is the flag of the Army Corps of Engineers. Behind them are wooden two-storey buildings.
Major General Leslie R. Groves Jr., speaks to service personnel Oak Ridge Tennessee in August 1945.
Uncle Sam has removed his hat and is rolling up his sleeves. On the wall in front of him are three monkeys and the slogan: What you see here/ What you do here/ What you hear here/ When you leave here/ Let it stay here.
A billboard encouraging secrecy among Oak Ridge workers
Security poster, warning office workers to close drawers and put documents in safes when not being used
Soldiers and workmen, some wearing steel helmet, clamber over what looks like a giant manhole.
Allied soldiers dismantle the German experimental nuclear reactor at Haigerloch .
A shiny metal four-engined aircraft stands on a runway. The crew pose in front of it.
Silverplate B-29 Straight Flush . The tail code of the 444th Bombardment Group is painted on for security reasons.
Two mushroom clouds rise vertically.
The mushroom clouds of the atomic attacks on Hiroshima , Japan, 6 August 1945 (left) and Nagasaki , Japan, 9 August 1945 (right)
Men in suits and uniforms stand on a dais decorated with bunting and salute.
Presentation of the Army–Navy "E" Award at Los Alamos on 16 October 1945. Standing, left to right: J. Robert Oppenheimer , unidentified, unidentified, Kenneth Nichols , Leslie Groves , Robert Gordon Sproul , William Sterling Parsons .
A man in a suit is seated at a desk, signing a document. Seven men in suits gather around him.
President Harry S. Truman signs the Atomic Energy Act of 1946 , establishing the United States Atomic Energy Commission .
Manhattan Project monthly expenditures from January 1943 through the end of December 1946. In its peak month, August 1944, US$111.4 million was spent on the project.
The Lake Ontario Ordnance Works (LOOW) near Niagara Falls became a principal repository for Manhattan Project waste for the Eastern United States. [ 355 ] All of the radioactive materials stored at the LOOW site—including thorium , uranium , and the world's largest concentration of radium -226—were buried in an "Interim Waste Containment Structure" (in the foreground) in 1991. [ 356 ] [ 357 ] [ 358 ]