The federal agency says the gaseous diffusion plant has not been a public health hazard since 1990 and will stay that way unless one of the 50,000 UF6 cylinders is ruptured.
By Joe Walker firstname.lastname@example.org
A final health assessment by the Atlanta-based Agency for Toxic Substances and Disease Registry says the plant has posed "no apparent public health hazard" since 1990. Although people may have been exposed to plant toxins, the exposure "is not expected to cause any adverse health effects," it says.
The agency determined that a hazard could stem from the rupture or destruction of one or more depleted uranium hexafluoride (UF6) cylinders during a transportation accident involving fire, a plane crash, severe weather or other natural disaster. "Although such incidents are unlikely, they must be recognized as possible," the assessment said.
There are nearly 50,000 cylinders — containing toxic, corrosive, mildly radioactive UF6 — stored at the plant, a situation that worries some neighbors and the plant's citizens' advisory committee. Although Congress passed legislation in 1998 requiring that facilities be built to convert the contents into something safer, the Energy Department has repeatedly delayed the process.
Normally, UF6 is a solid resembling rock salt. It is most dangerous as a liquid while being heated to or cooled from the gas enriched at the plant.
The health agency said the plant should continue shipping the cylinders in special transport cylinders or overpacks approved by regulatory authorities.
Because of groundwater contaminated with lead and the cleaning solvent trichloroethylene (TCE), a past hazard existed for children near the plant who may have drunk water from any of four residential wells. The Energy Department replaced those and scores of other wells with municipal water in the 1990s and continues treating the groundwater. Measures should continue to ensure the old wells are not used and prevent new wells from being installed near the plant, the agency said.
Past and potential exposures to vinyl chloride from groundwater, and uranium and hydrogen fluoride (HF) from acute air exposures, are an indeterminate health hazard because information "is insufficient to make any other determination." The agency found that past long-term exposures to airborne uranium and HF were too mild to be a health concern.
Caustic HF is released from UF6 that is exposed to the air. Vinyl chloride is caused from the chemical breakdown of TCE. The agency said the plant should continue to monitor for contaminants, restrict public access to contaminated areas, be sure equipment can detect traces of degradation chemicals such as vinyl chloride, and develop a consistent soil-sampling program to assess airborne toxins in residential areas.
The report is available at the McCracken County Public Library, the Paducah Community College library, the Metropolis (Ill.) Public Library, Murray State University’s Waterfield Library and the DOE Environmental Information Center in Barkley Centre off Blandville Road near Milner & Orr Funeral Home.
Requests for copies of the report should be sent to Chief, Program Evaluation, Records and Information Services Branch, ATSDR, 1600 Clifton Road, NE, Mailstop E-60, Atlanta, GA 30333.