Project Rio Blanco was an underground nuclear test that took place on May 17, 1973 in

Rio Blanco County, Colorado Rio Blanco County is a county located in the U.S. state of Colorado. As of the 2020 census, the population was 6,529. The county seat is Meeker. The name of the county is the Spanish language name for the White River which runs through it. H ...

, approximately 36 miles (58 km) northwest of Rifle. Three 33-kiloton nuclear devices were detonated nearly simultaneously in a single emplacement well at depths of below ground level. The tests were conducted in fine-grain, low-permeability sandstone lenses at the base of the

Fort Union Formation The Fort Union Formation is a geologic unit containing sandstones, shales, and coal beds in Wyoming, Montana, and parts of adjacent states. In the Powder River Basin, it contains important economic deposits of coal, uranium, and coalbed methane. ...

and the upper portion of the

Mesaverde Formation The Mesaverde Group is a Late Cretaceous stratigraphic group found in areas of Colorado, New Mexico, Utah, and Wyoming, in the Western United States. History The Mesaverde Formation was first described by W.H.Holmes in 1877 during the Hayden ...

. This was the third and final natural-gas-reservoir stimulation test in the Plowshare program, which was designed to develop peaceful uses for nuclear explosives. The two previous tests were

Project Gasbuggy Project Gasbuggy was an underground nuclear detonation carried out by the United States Atomic Energy Commission on December 10, 1967 in rural northern New Mexico. It was part of Operation Plowshare, a program designed to find peaceful uses for ...

in New Mexico and

Project Rulison Project Rulison, named after the rural community of Rulison, Colorado, was an underground 40-kiloton nuclear test project in the United States on September 10, 1969, about SE of the town of Grand Valley, Colorado (now named Parachute, Col ...

in Colorado. The

United States Atomic Energy Commission The United States Atomic Energy Commission (AEC) was an agency of the United States government established after World War II by U.S. Congress to foster and control the peacetime development of atomic science and technology. President ...

conducted the test in partnership with CER Geonuclear Corporation and

Continental Oil Company Conoco Inc. ( ) was an American oil and gas company that operated from 1875 until 2002, when it merged with Phillips Petroleum to form ConocoPhillips. Founded by Isaac Elder Blake in 1875 as the "Continental Oil and Transportation Company". Curre ...

. A placard, erected in 1976, now marks the site where the test was conducted. The site is accessible via a dirt road, Rio Blanco County Route 29.

Devices

As the creation of tritium was of greatest concern, the three devices used were specially designed to reduce

tritium Tritium ( or , ) or hydrogen-3 (symbol T or H) is a rare and radioactive isotope of hydrogen with half-life about 12 years. The nucleus of tritium (t, sometimes called a ''triton'') contains one proton and two neutrons, whereas the nucleus of ...

production, creating less than tritium each, primarily from the medium surrounding the devices. To reduce emplacement costs, the devices were very narrow in diameter, less than wide.

References

{{US nuclear tests Explosions in 1973 May 1973 events in the United States American nuclear weapons testing American nuclear test sites Explosions in the United States Peaceful nuclear explosions Rio Blanco County, Colorado Underground nuclear weapons testing 1973 in Colorado