Volta
Science2 December 1942

Chicago Pile-1 — The First Chain Reaction

Also called: CP-1

On 2 December 1942, in the world’s first reactor — graphite and uranium stacked by Enrico Fermi beneath the stands of the University of Chicago’s football field — a man-made nuclear chain reaction sustained itself for the first time.

In a squash court under the west stands of Stagg Field at the University of Chicago, Fermi and his colleagues stacked some 40,000 graphite bricks and uranium in layers to build a "pile". On the afternoon of 2 December, as the cadmium control rods were slowly withdrawn, the clicking of the neutron counters rose to an unbroken roar and the chain reaction sustained itself for four and a half minutes.

Announcing the success, the physicist Arthur Compton telephoned Washington in code: "The Italian navigator has landed in the new world." Proof that a chain reaction was possible opened the way to the great plutonium reactors at Hanford — and the reactor later became the starting point of nuclear power.

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States and rulers at the time
United States — President Franklin D. Roosevelt
Places
Stagg Field, University of Chicago

People

  • Enrico Fermi1901 – 1954

    key figure · Italian-born physicist who, after receiving the 1938 Nobel Prize in Physics, emigrated to the US and achieved the first chain reaction with the world’s first reactor in Chicago in 1942

  • Leo Szilard1898 – 1964

    participant · Hungarian-born physicist who first conceived the nuclear chain reaction and persuaded Einstein to write to Roosevelt warning of the atomic bomb

Before and after

Later
1943 The Los Alamos Laboratory

Themes that include this event

  • The Birth of the Atomic Bomb1938 – 1949

    From the discovery of fission to the first Soviet bomb — Einstein’s letter, the Manhattan Project, the Trinity test, Hiroshima and Nagasaki, and the dawn of the nuclear age