Rocky Flats Plant

The Rocky Flats Plant was a United States manufacturing complex that produced nuclear weapons parts near Denver, Colorado. The facility's primary mission was the fabrication of plutonium pits, the fissionable part of a bomb that produces a nuclear explosion. The pits were shipped to other facilities to be assembled into complete nuclear weapons. Operated from 1952 to 1992 by private contractors Dow Chemical Company, Rockwell International Corporation and EG&G, the complex was under the control of the U.S. Atomic Energy Commission (AEC), succeeded by the Department of Energy (DOE) in 1977. The plant manufactured 1,000 to 2,000 pits per year. Plutonium pit production was halted in 1989 after EPA and FBI agents raided the facility and the plant was formally shut down in 1992. Rockwell then accepted a plea agreement for criminal violations of environmental law. At the time, the fine was one of the largest penalties ever in an environmental law case. Cleanup began in the early 1990s, and the site achieved regulatory closure in 2006. The cleanup effort decommissioned and demolished the entire plant, more than 800 structures; removed over 21 tons of weapons-grade material; removed over 1.3 million cubic meters of waste; and treated more than 16 million US gallons (61,000 m3) of water. Four groundwater treatment systems were also constructed. The site of the former facility consists of two distinct areas: the "Central Operable Unit", which remains off-limits to the public as a CERCLA Superfund site, owned and managed by the U.S. Department of Energy, and the Rocky Flats National Wildlife Refuge, owned and managed by the U.S. Fish and Wildlife Service. Every five years, the U.S. Department of Energy, U.S. Environmental Protection Agency, and Colorado Department of Public Health and Environment review environmental data and other information to assess whether the remedy is functioning as intended. The latest Five-Year Review for the site, released in August 2022, concluded the site remedy is protective of human health and the environment. However, a protectiveness deferred determination was made for PFAS.

History

1950s

Following World War II, the United States increased production of nuclear weapons. A 4-square-mile (10 km2) site about 15 miles (25 km) northwest of Denver on a windy plateau called Rocky Flats was chosen for the facility. Contemporary news reports stated that the site would not be used to produce nuclear bombs, but might be used to produce uranium and plutonium components for use in nuclear weapons. The construction of Rocky Flats began in July 1951 and was a significant boon to the Colorado economy. Colorado state highways 72 and 93 were constructed to access the plant. Direct government construction contracts to Colorado business were worth $26 million ($315 million in 2025) and employed 2,800 people. By April 1953, the plant began operating under Dow Chemical company. What the plant made, when construction was finished, when it began making its products, and how much product it was making was secret. Routine production processes began immediately leaking plutonium into the atmosphere. A later study on the risks to public health from Rocky Flats estimated that normal operations leaked up to 130,000 microcuries of plutonium annually into the atmosphere as part of its production processes during the 1950s. This routine leakage declined in the 1960s and continued down to 60 picocuries in 1989. For residents living in the area most contaminated by Rocky Flats, this is a comparable exposure to the plutonium from fallout of nuclear weapons testing. This does not include the much higher levels of exposure as a result of the later fires. Rocky Flats was established next to Walnut Creek and Woman Creek. Until the construction of a waste treatment facility in 1957, plutonium contaminated wastewater was discharged directly into Walnut Creek which flowed into Broomfield's drinking water supply. In 1953, a retention pond was built along Walnut Creek which accumulated plutonium in its soil. In addition to plutonium and uranium contamination, the pond absorbed chemicals used in the production process such as algicides and chromates. Sewer water was originally designed to route to trenches on the property. The original wastewater system was not 100% isolated from the sewer, resulting in the trenches also being contaminated with uranium and plutonium. These trenches filled up in 1968. The AEC called Rocky Flats a "Weapon Production Facility" in a 1956 report. At this time, the plant was expanded with an additional $18.4 million ($218 million in 2025) investment from the AEC.

In June 1957 two employees were taken to the onsite hospital after an explosion in the production line. They were treated for cuts from flying glass and exposure to plutonium. On September 11, 1957, a plutonium fire occurred in one of the gloveboxes used to handle radioactive materials, igniting the combustible rubber gloves and plexiglas windows of the box. Metallic plutonium is a fire hazard and pyrophoric; under the right conditions it may ignite in air at room temperature. The fire escaped containment in under thirty minutes and the firefighters were forced to use water, a risky decision on plutonium fire, to put out the fire in the glovebox. After putting out the original source, there was an explosion in the ventilation system. The fire burned the filters that normally removed the plutonium from the building's air resulting in the release of 21 curies of plutonium into the atmosphere. For comparison the Fat Man, used 448 curies of plutonium for its core. The accident resulted in the contamination of Building 771 and caused $818,600 ($9.38 million in 2025) in damage. At the time, the AEC spokesman significantly downplayed the risk of plutonium exposure and estimated only $50,000 in damages. An incinerator for plutonium-contaminated waste was installed in Building 771 in 1958. The offgas was treated with scrubbers and filters and eventually released to the atmosphere. The ash was occasionally able to be reprocessed for plutonium recovery.

1960s

… excerpt ends here. Continue reading the full article.