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Manhattan Project facts for kids

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The Manhattan Project was the program based in the United States which tried to make the first nuclear weapons. The project went on during World War II, and was run by the U.S. Army. The head of the project was General Leslie R. Groves, who had led the building of the Pentagon. The top scientist on the project was Robert Oppenheimer, a famous physicist. The project cost $2 billion, and created many secret cities and bomb-making factories, such as a laboratory in Los Alamos, New Mexico, a nuclear reactor in Hanford, Washington, and a uranium processing plant in Oak Ridge, Tennessee.

The Manhattan Project had to find solutions to two difficulties. The first difficulty is how to make the special isotopes of uranium or plutonium. This process is called separation and is very slow. The United States built very big buildings with machines for separation. They made enough fissionable special isotopes for a few nuclear weapons. The second difficulty was how to make a bomb that will produce a big nuclear explosion every time. A weapon with a broken design will often make a much smaller nuclear explosion. This is called a "fizzle". In July 1945, the Manhattan Project solved the two difficulties and made the first nuclear explosion. This test of a nuclear weapon was called "Trinity" and was a success.

The Manhattan Project created two nuclear bombs which the United States used against Japan in 1945.

Espionage

Oak Ridge Wise Monkeys
A billboard encouraging secrecy among Oak Ridge workers

The Manhattan Project operated under a blanket of tight security. This was to prevent the Axis countries, especially Nazi Germany, from accelerating their own nuclear projects or undertaking covert operations against the project. The possibility of sabotage was always present. At times, people suspected sabotage when equipment failed. 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 fire balloon struck a power line, and the resulting power surge caused the three reactors at Hanford to be temporarily shut down.

Maintaining security was difficult because so many people worked on the project. A special Counter Intelligence Corps detachment handled the project's security issues. By 1943, it was clear that the Soviet Union was trying to penetrate the project. 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. Oppenheimer informed Pash that he had been approached by a fellow professor at Berkeley, Haakon Chevalier, about passing information to the Soviet Union.

The most successful Soviet spy was Klaus Fuchs. Fuchs was a member of the British Mission who played an important part at Los Alamos. The 1950 revelation of Fuchs' espionage activities damaged the United States' nuclear cooperation with Britain and Canada. Subsequently, other instances of espionage were uncovered, leading to the arrest of Harry Gold, David Greenglass and Ethel and Julius Rosenberg. Other spies like George Koval remained unknown for decades. People will never know the value of the espionage. One reason was that the Soviet atomic bomb project was held back by a shortage of uranium ore. The consensus is that espionage saved the Soviets one or two years of effort.

For more details, see Nuclear espionage

Images for kids

  • Manhattan Project emblem

    Circular shaped emblem with the words "Manhattan Project" at the top, and a large "A" in the center with the word "bomb" below it, surmounting the US Army Corps of Engineers' castle emblem

  • Six men in suits sitting on chairs, smiling and laughing.

    A 1940 meeting at Berkeley: 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

    Manhattan Project Organization 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.

  • 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

  • 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. Photograph by the Manhattan District photographer Ed Westcott.

  • A group of men in shirtsleeves sitting on folding chairs.

    Physicists at a Manhattan District-sponsored colloquium at the Los Alamos Laboratory on the Super in April 1946. In the front row are Norris Bradbury, John Manley, Enrico Fermi and J. M. B. Kellogg. Robert Oppenheimer, in dark coat, is behind Manley; to Oppenheimer's left is Richard Feynman. The Army officer on the left is Colonel Oliver Haywood.

  • Los Alamos map

    Map of Los Alamos site, New Mexico, 1943-45

  • 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.

  • 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.

    Giant Alpha I racetrack at Y-12

  • A long corridor with many consoles with dials and switches, attended by women seated on high stools.

    Operators, so-called Calutron Girls, photographed by Ed Westcott, at their calutron control panels at Y-12. Gladys Owens, the woman seated in the foreground, did not know what she had been involved with until seeing this photo in a public tour of the facility fifty years later.

  • 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 smoke stacks).

  • 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.

  • 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.

  • 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

  • Are your drawers closed? Manhattan Project security poster

    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.

  • 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.

  • Aerial view of Niagara Falls Storage Site, Lewiston, New York (2002)

    The Lake Ontario Ordnance Works (LOOW) near Niagara Falls became a principal repository for Manhattan Project waste for the Eastern United States. All of the radioactive materials stored at the LOOW site—including thorium, uranium, and the world's largest concentration of radium-226—were placed into an "Interim Waste Containment Structure" (in the foreground) in 1991.

  • Ames Process pressure vessel lower

    A "bomb" (pressure vessel) containing uranium halide and sacrificial metal, probably magnesium, being lowered into a furnace

  • Ames Process pressure vessel remnant slag after reaction

    After the reaction, the interior of a bomb coated with remnant slag

  • Ames Process uranium biscuit

    A uranium metal "biscuit" from the reduction reaction

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