“Chicago Pile-1: A Brick History” | A historical LEGO film made for @Argonne National Laboratory

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In 1942, underneath the University of Chicago’s
football stadium, a group of scientists led by Enrico Fermi built the world’s first
nuclear reactor. The reactor was built out of graphite blocks,
some of which contained small disks of uranium. Fermi knew if they arranged the blocks correctly, it would produce a self-sustaining nuclear reaction. A sphere would’ve been the best shape for
the reactor, but Fermi’s team couldn’t build a perfect sphere out of rectangular
blocks, and they weren’t sure exactly how big the reactor needed to be. There were no instructions to follow, so they
conducted a series of experiments to estimate the correct size for the reactor. First they built a rectangular pile. Then they ran an experiment. One scientist slowly pulled control rods out
of the pile, which allowed the nuclear reaction to proceed. Another monitored the reaction on instruments
nicknamed after Winnie the Pooh characters. Other scientists stood by with containers
of cadmium nitride in case of an emergency. The measurements from this experiment helped
Fermi conclude that the final reactor needed to be a rough sphere with a diameter of about
25 feet. They took apart the experimental pile and
began construction on the reactor, which they called Chicago Pile-1. As the pile grew, the team repeated the same
experiment again and again. The data from these experiments allowed Fermi
to conclude that the reactor didn’t need to be built all the way to the height he initially
planned. After the 57th layer of the pile was in place,
Fermi called construction to a halt. On December 2, 1942, Fermi assembled the whole
team to watch the experiment. That morning, they pulled out the control
rods as usual. The geiger counter beeped faster and faster,
indicating their goal was close. Fermi knew that with one small adjustment
they could run the experiment again and achieve their long-anticipated goal. So he called for a lunch break. After lunch, the experiment resumed. (Tense music swells) Criticality had been achieved. The team toasted their accomplishment with Chianti drunk from small paper cups.

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