Piles of piles: An inter-country comparison of nuclear pile development during World War II B. Cameron Reed Department of Physics (Emeritus) Alma College Alma, Michigan 48801 USA
[email protected] January 23, 2020 Abstract Between the time of the discovery of nuclear fission in early 1939 and the end of 1946, approximately 90 “nuclear piles” were constructed in six countries. These devices ranged from simple graphite columns containing neutron sources but no uranium to others as complex as the water-cooled 250-megawatt plutonium production reactors built at Hanford, Washington. This paper summarizes and compares the properties of these piles. 1 1. Introduction According to the World Nuclear Association, there were 448 operable civilian nuclear power reactors in the world with a further 53 under construction as of late 2019.1 To this total can be added reactors intended for other purposes such as materials testing, medical isotope production, operator training, naval propulsion, and fissile materials production. All of these reactors are the descendants, by some path or other, of the first generation of nuclear “piles” developed in the years following the discovery of nuclear fission in late 1938. Any historian of science possessing even only a passing knowledge of developments in nuclear physics during World War II will be familiar with how Enrico Fermi achieved the first self-sustaining chain reaction with his CP-1 (“Critical Pile 1”) graphite pile at the University of Chicago on December 2, 1942, and how this achievement led to the development, within two years, of large-scale plutonium production reactors at Hanford, Washington.