SciTech Tuesday: Dawn of the Nuclear Age

Sunday, December 2, 2012, marked the 70^th anniversary of the first controlled nuclear chain reaction. In his laboratory on a beneath the football stadium at the University of Chicago, Enrico Fermi and a team of 48 scientists gathered on a converted squash court to witness the turning point in the pursuit of nuclear power.

In a nuclear chain reaction a speeding neutron causes fission or splits the atom’s nucleus, releasing energy and emitting two neutrons. The resulting neutrons can split other nuclei, generating more neutrons, and thereby causing a self-sustaining reaction which can continue on its own. Fermi controlled the fission by inserting cadmium-plated control rods into uranium-235 to absorb neutrons. By then removing the rods one at a time, he allowed the reaction to increase slowly until it was self-sustaining with the number of emitted neutrons increasing exponentially.

Enrico Fermi’s nuclear chain reaction allowed physicists to harness the immense power of the nucleus, a critical step in the ability of the Manhattan Project to produce the first atomic bomb. At 3:53 p.m. on December 2, 1942, the coded message, “The Italian navigator has just landed in the new world,” delighted President Roosevelt and the nuclear age was born.

Post by Annie Tête, STEM Education Coordinator

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