Chicago Pile-1
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On December 2, 1942, the world's first artificial self-sustaining nuclear chain reaction took place in the world's first nuclear reactor, Chicago Pile Number One, shortened as CP-1, built on a racquets court under the abandoned west stands of the Alonzo Stagg Field stadium on the University of Chicago campus. Operation of CP-1 was terminated in February 1943 and the nuclear reactor dismantled and moved to the laboratory's Palos Park site A. It was reconstructed using CP-1 materials but enlarged with a radiation shield and named CP-2. It began operation in March 1943.
The reactor was a pile of uranium and graphite blocks, assembled under the supervision of the renowned Italian physicist Enrico Fermi. It contained critical mass of the fissile material, together with control rods, and was built as a part of Manhattan Project research done by the University of Chicago Metallurgical Laboratory. The shape of the pile was intended to be roughly spherical, but as work proceeded, Fermi calculated that critical mass could be achieved without finishing the entire pile as planned.
A labor strike prevented the construction of the pile at a laboratory in the Argonne forest preserve, so Fermi and his associates Martin Whittaker and Walter Zinn set about building the pile (the world's first "nuclear reactor," although that term was not used until 1952) in a racquets court under the abandoned west stands of the university’s Stagg Field. The pile consisted of uranium pellets as a neutron–producing "core" separated from one another by graphite blocks to slow the neutrons. Fermi himself described the apparatus as "a crude pile of black bricks and wooden timbers." The controls consisted of cadmium-coated rods that absorbed neutrons. Withdrawing the rods would increase neutron activity in the pile to lead to a self-sustaining chain reaction. Re-inserting the rods would dampen the reaction.
On December 2, 1942, Chicago Pile 1 (CP-1) was ready for a demonstration. Before a group of dignitaries, a young scientist named George Weil worked the final control rod while Fermi carefully monitored the neutron activity. The pile went critical at 3:20 p.m. Fermi shut it down 33 minutes later. In 1943, he rebuilt the pile as CP-2 at the Argonne Laboratory.
A small graphite block from the pile is on display at the Museum of Science and Industry in Chicago.
See also
References
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Illustrations (external site)
- [Drawing of the first atomic pile] Artist drawing of CP-1
- [AtomicArchive.com] Photographs from assembling the pile
External links
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