Chicago Pile-1

Chicago Pile-1 (CP-1) was the world's first artificial nuclear reactor, achieving the first self-sustaining nuclear chain reaction on December 2, 1942, beneath the stands of the University of Chicago's abandoned football stadium. Built by Enrico Fermi and his team as part of the Manhattan Project, the reactor was a lattice of uranium and graphite that demonstrated what Leo Szilard had patented theoretically: that controlled fission was possible.

The reactor's design was deliberately conservative — no radiation shield, no cooling system, just a pile of graphite bricks and uranium slugs stacked in a squash court. This was engineering by the seat of the pants, but it worked. The chain reaction reached a power of 0.5 watts, enough to prove the principle and begin the design of the reactors that would produce plutonium for atomic weapons.

Chicago Pile-1 is the origin point of the nuclear age. Every subsequent reactor, power plant, and research facility traces its lineage to this improvised structure. The question it raised — whether humanity could control a force it had just learned to release — remains unanswered.