The world's first self-sustaining nuclear reaction did not take place in a laboratory
nor did it occur in some remote desert,
though that might make sense if you're about to attempt to control a power
that no one has ever attempted to control before!
Instead, on December 2nd, 1942, a team of forty-nine scientists and students,
led by Enrico Fermi, activated the world's first nuclear reactor
in a converted squash court
beneath the football stands of Stag Field, at the University of Chicago.
Yes, "Chicago" Chicago.
Dubbed "Chicago Pile 1",
the nuclear reactor built by Fermi's team,
was hardly the complex machine you might expect.
It contained no mechanical parts, or wires,
and in the twenty-or-so minutes it operated it generated roughly one-half a watt of power.
Just enough to power a lamp.
Four years earlier, German scientists had become
the first to accomplish nuclear fission
by bombarding atoms of uranium with neutrons
to split their nuclei in two.
This caused a release of energy and additional neutrons
that then split other nuclei to begin a chain reaction.
But, no one figured out how to harness that power,
which many scientists correctly assumed could be used to build powerful atomic weapons.
Fermi's pile consisted of alternating layers of uranium pellets and graphite.
Uranium was the fuel, emitting neutrons that every so often
would strike the nuclei of other uranium atoms and foster the chain reaction.
The graphite acted like a moderator of sorts, slowing down the neutrons
which made it easier for them to strike other uranium nuclei.
The key of course, and this is a very important key,
is to figure out a way to start, stop, and regulate this chain reaction.
Fermi found his answer in the form of cadmium rods,
which naturally absorb neutrons during the fission process.
His team quickly discovered that the energy output could be increased or decreased
by adjusting these rods, which were the only moving parts of the pile.
It took several weeks to build, and once complete,
the pile contained 380 tons of graphite,
40 tons of uranium oxide, and 6 tons of uranium metal.
There were 57 layers in all,
Just enough to reach critical mass, the stage necessary to sustain a chain reaction.
At 2 p.m. on December 2nd, the last cadmium rod was pulled out of the pile.
Less than 90 minutes later, Fermi announced that the reactor had
achieved critical mass and the world had its first controlled self-sustaining nuclear chain reaction.
Those present opened a bottle of Chianti to celebrate,
but presumably they didn't get too drunk.
Now, despite rumors to the contrary,
there were never dangers of the reactor causing a nuclear disaster.
With so little fuel the worst-case-scenario involved the pile catching fire
and causing a very little, mini-meltdown,
if one can speak of a "mini-meltdown."
Also, the Argonne National Laboratory,
which was founded by Fermi and a few others, years after the experiment,
would like to dispel another myth, that the forty-nine people present that day
all died early from cancer.
In fact, that is not true.
At least two of those on the squash court are still alive today, more than seventy years later
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