Manson Benedict

A neutron is fired at uranium-235, splitting the atom’s nucleus into pieces. This process – called “fission” – powered “Little Boy,” the 1945 nuclear bomb dropped on Hiroshima.

The bomb works by sparking a chain reaction of neutrons striking nearby nuclei and releasing high amounts of energy in the form of a devastating explosion.

But the bomb’s key ingredient, uranium-235 – an isotope with a different atomic weight than its original element – wasn’t easy to come by in nature.

Manson Benedict, a scientist with the Manhattan Project, solved this problem, devising a way to separate uranium-235 from uranium-238 using a method called “gaseous diffusion.”

The process required a massive facility to house hundreds of cascades for reactions to take place.

Benedict – who would eventually become MIT’s first professor of nuclear engineering – supervised the building of Tennessee's K-25 plant where the fission-ready uranium isotopes used in “Little Boy” were produced.