Between 1961 and 1973 the United States conducted a series of controlled nuclear and non-nuclear blasts in Nevada, New Mexico, Colorado, California, Montana and Idaho called “Operation Plowshare.” These were referred to as “Peaceful Nuclear Explosions” or PNEs, and their purpose was to find uses for atomic power in large-scale construction projects such as harbors, interstate highways, railroads through mountains, and in the search for oil, gas, and water; as well as gathering geological information about the earth’s deep crust. Plowshare consisted of 27 nuclear detonations, starting with “Project Gnome” (December 1961) and ending with the three-part “Project Rio Blanco” (May 1973). Involved also were non-nuclear tests that increased knowledge about a range of effects of large explosives depending on placement and scale.
The best-known Plowshare test was the thermonuclear blast, test-named “Sedan,” in July 1962 at the Nevada Test Site near Groom Lake in the CIA’s Area 51. It shot a radioactive plume 12,000 feet into the air detected in states even east of the Mississippi River, and created the world’s largest man-made crater, measuring 1300 feet wide and 300 feet deep. Information reaped from such tests led to the determination that the Barringer Crater in Arizona formed from a impact meteor, not from volcanic eruption.
Plowshare had many nuclear projects proposed but not carried out. These included studies of the cratering characteristics of various rock types, accessing tar sands in Athabasca, Alberta; widening the Panama Canal or changing the route entirely; and harbor projects in Australia. The Soviet Union had a comparable, though larger, program for exploring the peaceful uses of atomic power called “Nuclear Explosions for the National Economy” consisting of almost 160 blasts and lasting from 1965 to 1989 when Mikhail Gorbachev brought the program to a close. Plowshare vividly carried out President Eisenhower’s “Atoms for Peace” initiative introduced in a December 1953 speech on civilian uses of nuclear power that contrasted markedly with the early stages of the Cold War that saw atomic power in terms of military policy with such concepts as massive retaliation and the later “mutually-assured destruction (MAD).”