atomic pile

Meanings

1. An early nuclear reactor fueled by uranium and moderated with graphite.

Etymology

From the fact that the first nuclear reactor, at the University of Chicago in 1942-1943, was literally constituted by a tall pile (heap) of graphite moderator blocks. Compare also charcoal pile, a traditional improvised kiln used in charcoal making, which uses a similar basic design to contain a volatile process. The fact that English pile also is related to French pile (“battery”) (with senses of a collection of components and a power source, often both coinstantiated) has also been noted as an interesting nexus of word roots and semantic themes.