LEMONT, Ill. -- If it's possible to pinpoint the moment when the nuclear age began, it was December 2, 1942. Under the stands at the University of Chicago's Stagg Field, inside a closed-off squash court, 49 of the world's best physicists watched as the first-ever nuclear reactor went critical. And, having proved that such a self-sustaining chain reaction was possible, a key moment in the study of the nuclear synthesis of plutonium for bombs, the arms race was on.

Known as Chicago Pile-1, this was the reactor that was built by Enrico Fermi and many others to demonstrate that a nuclear chain reaction was possible. The effort, done under the auspices of the University of Chicago's Metallurgical Laboratory, the precursor to Argonne National Lab, was a key step in the development of the Manhattan Project, the creation of the atomic bomb.

This is an artist's drawing of Chicago Pile-1, which was created in about a month. It was a pile, 24 feet wide by 24 feet long, and 19 feet high, of machined uranium and graphite blocks.

As part of Road Trip 2013, CNET reporter Daniel Terdiman visited the Nuclear Energy Exhibit at Argonne National Lab to learn the history of Chicago Pile-1.

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Photo by: Argonne National Lab / Caption by:

Scale model of Stagg Field

This scale model, housed in the Nuclear Energy Exhibit at Argonne National Laboratory in Lemont, Ill., shows how the Chicago Pile-1 project was constructed inside the squash court under the bleachers at the University of Chicago's football field.

According to a document (PDF) hosted on the U.S. Department of Energy's Web site, that location was chosen in a hurry after the first choice, the Argonne Woods, was abandoned due to "slow construction." As a result, "the largest space available" was selected.

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Photo by: Daniel Terdiman/CNET / Caption by:

Scale model with person

This scale model of Pile-1 shows its size relative to a human being. All together, according to the document hosted on the Department of Energy's Web site, the pile contained 385.5 tons of graphite and 46.5 tons of uranium metal and oxides.

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Photo by: Daniel Terdiman/CNET / Caption by:

Scale model showing gallery

This view of the scale model in the Nuclear Energy Exhibit at Argonne National Lab shows where the people who viewed the experiment watched from.

In addition, it also shows (if you look closely) that a man was stationed against the railing holding on to a rope that pulled a control rod. In an emergency, that rope was supposed to be cut, which would slide the rod into the core, absorbing neutrons and stopping the chain reaction.

As a backup safety measure, buckets of cadmium in liquid were ready to be poured over the pile, which would leak into it and shut down the reaction, according to Roger Blomquist, a nuclear engineer at Argonne National Lab.

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Photo by: Daniel Terdiman/CNET / Caption by:

The birth certificate of the atomic age

This chart, known as the "birth certificate of the atomic age," according to Argonne National Lab, shows the neutron intensity as measured by a galvanometer during the world's first-ever controlled nuclear chain reaction on December 2, 1942.

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Photo by: Argonne National Lab / Caption by:

Memorial of Chicago Pile-1

Chicago Pile-1 was dismantled almost as fast as it was constructed, and it was quickly re-assembled in the Argonne Woods near today's Argonne National Lab. Today, all that remains of one of history's most important technological events is this memorial, found in the middle of the University of Chicago.

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Photo by: Daniel Terdiman/CNET / Caption by:

Plaque

A plaque near the memorial at the University of Chicago reads, "On December 2, 1942, man achieved here the first self-sustaining chain reaction and thereby initiated the controlled release of nuclear energy."

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Photo by: Daniel Terdiman/CNET / Caption by:

Fermi

Enrico Fermi won the Nobel Prize in 1938. As the leader of the Pile-1 project, he was the man most responsible for demonstrating that man could tame nuclear energy. According to Argonne National Lab's Blomquist, nobody has ever combined a mastery of physics and mathematics at such a high level as Fermi.

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Photo by: Argonne National Lab / Caption by:

Packing graphite

In this 1956 photograph, Walter Zinn, one of the leaders of the Chicago Pile-1 experiment, oversees technicians putting graphite from the CP-1 reactor into a storage facility in Building 24 on the current Argonne National Lab campus.

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Photo by: Argonne National Lab / Caption by:

Chianti

After the successful completion of the Chicago Pile-1 experiment -- which Fermi concluded after about 28 minutes of a self-sustaining chain reaction -- each of the 49 people on hand were given a small amount of chianti from this bottle, seen in a photograph at the Argonne National Lab.

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Photo by: Argonne National Lab / Caption by:

Signatures

The signatures, collected 20 years later, of most of the 49 scientists involved in the Chicago Pile-1 experiment. Notably missing is Fermi's signature.

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Photo by: Argonne National Lab / Caption by:

Graphite

The pile, which was built on top of a wooden frame on the squash court under the Stagg Field bleachers, consisted of "alternate layers of graphite, containing uranium metal and/or oxide," according to the document on the Department of Energy's Web site, which "were separated by layers of solid graphite blocks to form a lattice structure."

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Photo by: Daniel Terdiman/CNET / Caption by:

'We're cooking'

This record shows the progress of the Chicago Pile-1 experiment, and at the bottom left of the right-hand page, "We're cookin!" was written to signify that the experiment was successful. That phrase was used, according to a placard at the Argonne National Lab's Nuclear Energy Exhibit, because "a nuclear reaction has been likened to the burning of a pile of oily rags that in certain circumstances can ignite spontaneously."

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Photo by: Daniel Terdiman/CNET / Caption by:

Photo of Stagg Field

This photograph, on the wall of the Argonne National Lab's Nuclear Energy Exhibit, shows the University of Chicago's Stagg Field bleachers, inside of which the Chicago Pile-1 experiment was conducted in secret.

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Photo by: Daniel Terdiman/CNET / Caption by:

Chicago Pile-2

This photograph, hosted by the Argonne National Lab, depicts Chicago Pile-2 in 1943. The so-called CP-2 was created "when Chicago Pile 1, the world's first nuclear reactor, was dismantled and moved to the Cook County Forest Preserve near Palos Hills, Ill.. At the new, isolated location, the reactor was reassembled with some refinements and modifications and renamed Chicago Pile 2. CP-2 had a thermal-power level of 10 kW and was fueled by natural uranium. A small laboratory atop the 14,000-ton reactor provided space for limited experiments using neutrons from the reactor's core. The reactor's face contained ports through which materials could be inserted into the core for irradiation."

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Photo by: Daniel Terdiman/CNET / Caption by:

Site A

Originally selected as the home for the world's first nuclear reactor and the first-ever sustained chain reaction, Site A, in the Argonne Woods, was host to a re-creation of Chicago Pile-1 immediately after the successful experiment conducted at the University of Chicago. CP-1 was dismantled and reassembled at Site A.

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Photo by: Argonne National Lab / Caption by:
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