Atomic Energy Act of 1946

President Harry S. Truman signs the Atomic Energy Act into law on August 1, 1946. Behind the President, left to right, are Senators Tom Connally, Eugene D. Millikin, Edwin C. Johnson, Thomas C. Hart, Brien McMahon, Warren R. Austin and Richard B. Russell Jr.
The first five Atomic Energy Commissioners. Left to right: Robert Bacher, David E. Lilienthal, Sumner Pike, William W. Waymack and Lewis L. Strauss

The Atomic Energy Act of 1946 (McMahon Act) determined how the United States would control and manage the nuclear technology it had jointly developed with its World War II allies, the United Kingdom and Canada.

- Atomic Energy Act of 1946

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Brien McMahon

American lawyer and politician who served in the United States Senate (as a Democrat from Connecticut) from 1945 to 1952.

McMahon Commemorative Stamp, 1962

McMahon was a major figure in the establishment of the Atomic Energy Commission, through his authorship of the Atomic Energy Act of 1946 (the McMahon Act).

United States Atomic Energy Commission

Agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology.

President Harry S. Truman signs the Atomic Energy Act of 1946
David E. Lilienthal, who chaired the AEC from its creation until 1950
Gordon Dean, who chaired the AEC from 1950 to 1953
Dr. Joseph G. Hamilton was the primary researcher for the human plutonium experiments done at U.C. San Francisco from 1944 to 1947. Hamilton wrote a memo in 1950 discouraging further human experiments because the AEC would be left open "to considerable criticism", since the experiments as proposed had "a little of the Buchenwald touch".
President Dwight D. Eisenhower with AEC chair Lewis Strauss in 1954
AEC chair John A. McCone presents the Enrico Fermi Award to Glenn T. Seaborg in 1959. Seaborg succeeded McCone as AEC chair in 1961.
AEC chair Glenn T. Seaborg with President John F. Kennedy in 1961
AEC chair James R. Schlesinger with President Richard M. Nixon and First Lady Pat Nixon at the AEC's Hanford Site in 1971
Dixy Lee Ray, last person to chair the AEC, with Robert G. Sachs, director of the Argonne National Laboratory

President Harry S. Truman signed the McMahon/Atomic Energy Act on August 1, 1946, transferring the control of atomic energy from military to civilian hands, effective on January 1, 1947.

United States Sixth Fleet

Numbered fleet of the United States Navy operating as part of United States Naval Forces Europe.

The U.S. Sixth Fleet's seal
The U.S. Sixth Fleet in 1954.
U.S. ships in Sicily, 1965
The Sixth Fleet's area of responsibility, 2009.
The newly elected president of Liberia, Ellen Johnson-Sirleaf, tours the U.S. Navy's Sixth Fleet command and control ship USS Mount Whitney (LCC 20) escorted by Commander, Task Force 65, Captain Tom Rowden, right, while the frigate USS Carr (FFG 52) moves alongside the ship. Making her first ever visit aboard a navy vessel, President Johnson-Sirleaf visited Mount Whitney the day after her inauguration to thank the crew for making the journey in support of her country's inaugural ceremonies.

STRIKEFORSOUTH was effectively the NATO designation for the U.S. Sixth Fleet, though additional NATO headquarters personnel would eventually be assigned, while maintaining American control over its nuclear weapons on board U.S. aircraft carriers as mandated by the Atomic Energy Act of 1946.

Harold Urey

American physical chemist whose pioneering work on isotopes earned him the Nobel Prize in Chemistry in 1934 for the discovery of deuterium.

Harold Urey
The S-1 Executive Committee at Bohemian Grove, September 13, 1942. From left to right are Urey, Ernest O. Lawrence, James B. Conant, Lyman J. Briggs, Eger V. Murphree, and Arthur H. Compton.
Miller–Urey experiment

Urey actively campaigned against the 1946 May-Johnson bill because he feared that it would lead to military control of nuclear energy, but supported and fought for the McMahon bill that replaced it, and ultimately created the Atomic Energy Commission.

United States Congressional Joint Committee on Atomic Energy

United States congressional committee that was tasked with exclusive jurisdiction over "all bills, resolutions, and other matters" related to civilian and military aspects of nuclear power from 1946 through 1977.

The Senate Armed Services Committee chairman Carl Levin and ranking member John Warner in 2007 hearing opening statements during a confirmation hearing for a position in the Department of Defense.

It was established by the United States Atomic Energy Act of 1946, and was the overseer of the United States Atomic Energy Commission.

Atomic Energy Act of 1954

United States federal law that covers for the development, regulation, and disposal of nuclear materials and facilities in the United States.

President Eisenhower signs the bill in an official signing ceremony.

It was an amendment to the Atomic Energy Act of 1946 and substantially refined certain aspects of the law, including increased support for the possibility of a civilian nuclear industry.

Manhattan Project

Research and development undertaking during World War II that produced the first nuclear weapons.

The Trinity test of the Manhattan Project on 16 July 1945 was the first detonation of a nuclear weapon.
Enrico Fermi, John R. Dunning, and Dana P. Mitchell in front of the cyclotron in the basement of Pupin Hall at Columbia University
March 1940 meeting at Berkeley, California: Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, James B. Conant, Karl T. Compton, and Alfred L. Loomis
Different fission bomb assembly methods explored during the July 1942 conference
Manhattan Project Organization Chart, 1 May 1946
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.
Groves confers with James Chadwick, the head of the British Mission.
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.
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. (Jerome) M. B. Kellogg (1905-1981). 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.
Map of Los Alamos site, New Mexico, 1943–45
Hanford workers collect their paychecks at the Western Union office.
The majority of the uranium used in the Manhattan Project came from the Shinkolobwe mine in Belgian Congo.
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.
Alpha I racetrack at Y-12
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.
Oak Ridge K-25 plant
The S-50 plant is the dark building to the upper left behind the Oak Ridge powerhouse (with smoke stacks).
Workers load uranium slugs into the X-10 Graphite Reactor.
Aerial view of Hanford B-Reactor site, June 1944
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.
A row of Thin Man casings. Fat Man casings are visible in the background.
An implosion-type nuclear bomb
Remote handling of a kilocurie source of radiolanthanum for a RaLa Experiment at Los Alamos
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.
Major General Leslie R. Groves, Jr., speaks to service personnel Oak Ridge Tennessee in August 1945.
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
Allied soldiers dismantle the German experimental nuclear reactor at Haigerloch.
Silverplate B-29 Straight Flush. The tail code of the 444th Bombardment Group is painted on for security reasons.
Little Boy explodes over Hiroshima, Japan, 6 August 1945 (left);
Fat Man explodes over Nagasaki, Japan, 9 August 1945 (right).
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.
President Harry S. Truman signs the Atomic Energy Act of 1946, establishing the United States Atomic Energy Commission.
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 buried in an "Interim Waste Containment Structure" (in the foreground) in 1991.
A "bomb" (pressure vessel) containing uranium halide and sacrificial metal, probably magnesium, being lowered into a furnace
After the reaction, the interior of a bomb coated with remnant slag
A uranium metal "biscuit" from the reduction reaction

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.

Leo Szilard

Hungarian-American physicist and inventor.

Szilard, c. 1960
Leo Szilard aged 18
An image from the Fermi–Szilard "neutronic reactor" patent
Army Intelligence report on Enrico Fermi and Leo Szilard
The Metallurgical Laboratory scientists, with Szilard third from right, in the lab coat.
Szilard and Norman Hilberry at the site of CP-1, at the University of Chicago, some years after the war. It was demolished in 1957.
Salk Institute for Biological Studies, La Jolla, San Diego

Afterwards, he lobbied for amendments to the Atomic Energy Act of 1946 that placed nuclear energy under civilian control.

Quebec Agreement

Secret agreement between the United Kingdom and the United States outlining the terms for the coordinated development of the science and engineering related to nuclear energy and specifically nuclear weapons.

Mackenzie King, Franklin D. Roosevelt and Winston Churchill at the Quebec Conference in August 1943
Sir John Anderson, the minister responsible for Tube Alloys
Vannevar Bush, Director of the US Office of Scientific Research and Development
Lord Cherwell (foreground, in bowler hat) was scientific advisor to Winston Churchill (centre)
Vannevar Bush, James B. Conant, Leslie Groves and Franklin Matthias
Secretary of War, Henry L. Stimson (centre) with Field Marshals Sir Harold Alexander (left) and Sir Henry Maitland Wilson (right)
Press Conference at the Citadelle of Quebec during the Quadrant Conference. Left to right: President Franklin D. Roosevelt, Canadian Prime Minister Mackenzie King, and British Prime Minister Winston Churchill. Seated on the wall behind them are Anthony Eden, Brendan Bracken and Harry Hopkins.
James Chadwick, Leslie R. Groves, Jr., and Richard C. Tolman
The Hyde Park Aide-Mémoire. This copy is in the Franklin D. Roosevelt Presidential Library and Museum.
President Harry Truman and prime ministers Clement Attlee and Mackenzie King board the USS Sequoia (presidential yacht) for discussions about nuclear weapons, November 1945

The McMahon Act ended technical co-operation through its control of "restricted data".

James B. Conant

American chemist, a transformative President of Harvard University, and the first U.S. Ambassador to West Germany.

James Bryant Conant in 1932
Award of honorary degrees at Harvard to Robert Oppenheimer (left), George C. Marshall (third from left) and Omar N. Bradley (fifth from left) in June 1947. Conant sits between Marshall and Bradley. Marshall used the occasion to announce the Marshall Plan.
Conant at a meeting at the University of California, Berkeley in 1940. From left to right: Ernest O. Lawrence, Arthur H. Compton, Vannevar Bush, Conant, Karl T. Compton, and Alfred L. Loomis
President Harry S. Truman, center, in 1948 presents Conant, at right, with the civilian Medal for Merit award with bronze palm. Vannevar Bush watches at left.
Conant as United States High Commissioner for Germany, 1953.
From left to right in a November 1969 photo, Dr. Glenn Seaborg, President Richard Nixon, and the three awardees of the Atomic Pioneers Award: Dr. Vannevar Bush, Dr. James Conant, and Gen. Leslie Groves.

The Atomic Energy Act of 1946 replaced the wartime Manhattan Project with the Atomic Energy Commission (AEC) on January 1, 1947.