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Project Rulison 2, 8/13/10,

Issue Brief

Project Plowshare Overview

Project Plowshare is the common name for a series of nuclear explosive tests conducted in the 1960s and ‘70s for non-combat purposes. Early experiments included rock blasting, chemical element manufacture, and the probing of the composition of the Earth’s deep crust for geology and mining. The program culminated in 27 separate nuclear projects until environmental activism forced the Project’s cancellation in 1975. Activists cited the high potential for atmospheric fallout and contamination to water, soil, and wildlife.

Three Plowshare projects belonged to a set of tests designed to demonstrate that natural gas could be harvested from underground reservoirs using nuclear devices to fracture deep rock. Following the pilot test of Project Gasbuggy (New Mexico, 1967), Project Rulison was conducted on September 10, 1969, eight miles southeast of what is now the town of Parachute, Colorado. The detonation of a 40-kiloton nuclear device 8.400 feet underground did release the gas but irradiated it, making it unfit for use. Project Rio Blanco followed four years later and involved the simultaneous detonation of three 33-kiloton nuclear devices at 5,838, 6,230, and 6,686 below ground level. Both tests were partially funded by private oil, gas, and nuclear development companies working directly with the Atomic Energy Commission.

As a response to Rulison and Rio Blanco, the state of Colorado passed legislation in 1974 requiring a public vote to approve the detonation of nuclear bombs within state borders. The following year, Project Plowshare was cancelled in its entirety, making the Rio Blanco test the last full-scale nuclear bomb detonation for non-combat purposes in the United States. The Department of Energy commenced remediation of the Rulison site in the 1970s, and the site remains surrounded by a buffer zone. Historical markers were erected at both sites in 1976.


Center for Land Use Interpretation. "Nuclear Fracking: An Idea Whose Time Has Come, and Gone." Lay of the Land Newsletter, Winter 2013. Accessed August 1, 2020.

U.S. Atomic Energy Commission. "Operation Plowshare." Nuclear Vault video. Prelinger Archives San Francisco. Accessed August 1, 2020.

U.S. Department of Energy, Office of Legacy Management. "Geospatial Environmental Mapping System: Rio Blanco." Accessed August 1, 2020.

U.S. Department of Energy, Office of Legacy Management. "Geospatial Environmental Mapping System: Rulison." Accessed August 1, 2020.

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