The "official purpose" of Camp Century, as explained by the United States Department of Defense to Danish government officials in 1960, was to test various construction techniques under Arctic conditions, explore practical problems with a semi-mobile nuclear reactor, as well as supporting scientific experiments on the icecap. A total of 21 trenches were cut and covered with arched roofs within which prefabricated building were erected. 2 With a total length of 3,000 metres (1.9 mi), these tunnels also contained a hospital, a shop, a theater and a church. The total number of inhabitants was around 200. From 1960 until 1963 the electricity supply was provided by means of the world's first mobile/portable 3nuclear reactor, designated the PM-2A and designed by Alco for the U.S. Army. Water was supplied by melting glaciers and tested to determine whether germs such as the 4plaguewere present.