ARGONNE NATIONAL LABORATORY / SCIENCE PHOTO LIBRARY ARGONNE NATIONAL LABORATORY / SCIENCE PHOTO LIBRARY
Layer 10 of the atomic pile in which the first self-sustaining nuclear chain reaction occurred on December 2, 1942. The pile was built by a team led by the Italian physicist Enrico Fermi in a squash court under the stands of Chicago University's Stagg Field. Layer 10 contained many spherical "slugs" of uranium (in mixed metal & oxide form), seen in the holes. Note that some of the peripheral holes have been refilled with graphite. The fuel layers alternated with layers of solid graphite bricks. The finished pile, which consisted of 57 layers, was enclosed in a tent of balloon fabric to minimise the loss of neutrons.
Model release not required. Property release not required.