The spelling of "reactor piles" may seem confusing due to the pronunciation. The word "reactor" is pronounced /riˈæktər/, with the stress on the second syllable, while "piles" is pronounced /paɪlz/, with the stress on the first syllable. When combined, the stress falls on the second syllable of each word, resulting in /riˈæktər paɪlz/. This term refers to stacks of fuel rods used in nuclear reactors. Despite the unusual pronunciation, the spelling correctly reflects the phonetics of the word.
The word "reactor piles" has its origins in the field of nuclear energy and specifically refers to early types of nuclear reactors.
The term "pile" in this context comes from the earliest work on nuclear fission carried out by Enrico Fermi and his team in the 1940s. Fermi conducted a series of experiments using uranium and graphite to study the behavior of neutrons and the possibility of sustaining a controlled chain reaction.
During these experiments, uranium blocks or rods were arranged in a stack or "pile" surrounded by graphite blocks, which acted as a moderator to slow down the neutrons. By adjusting the graphite blocks and uranium configuration, Fermi was able to achieve a self-sustaining nuclear reaction, marking the birth of the nuclear reactor.
Hence, the term "pile" originated from the stack or arrangement of uranium and graphite blocks used in these early nuclear experiments.