Sequoyah Fuels Corporation
Sequoyah Fuels Corporation (SFC) operated its Gore, Oklahoma uranium conversion facility, under Nuclear Regulatory Commission Materials Lisence SUB-1010, from 1970 until 1993. Various phases of SFC's operations produced radioactive waste streams. The site is an 85-acre, industrial area on a 600-acre site, located about 75 miles southeast of Tulsa, Oklahoma, just outside of Gore. The main process was the conversion of uranium oxide (yellowcake) to uranium hexafluoride. A second process, begun in 1987, consisted of the conversion of depleted uranium hexafluoride to uranium tetrafluoride. This site also processed uranium tetrafluoride to convert back into a more stable form.
A UF6 accident involving a cylinder rupture occurred at Sequoyah Fuels in 1986. The accident occurred when an over-loaded shipping cylinder was reheated to remove an excess of UF6. The cylinder ruptured, releasing a dense cloud of UF6 and its reaction products. On contact with moisture in the air, UF6 breaks down into uranyl fluoride and hydrofluoric acid, a highly corrosive chemical. The acid, which is used commercially to etch glass and clean metals, can kill almost immediately on contact. This accident resulted in the death of one individual from HF inhalation. An additional 31 workers were exposed to the released cloud. Although some of the more highly exposed workers showed evidence of short-term kidney damage (e.g., protein in the urine), none of these workers had lasting kidney toxicity from the uranium exposure.
The Sequoyah Fuels plant was purchased from the Kerr-McGee Corp. in 1988 for about $15 million. In late 1992, a reaction in a digester resulted in contamination of the facility soil and groundwater, causing the NRC to order the immediate shutdown of the entire facility. On 26 November 1992 General Atomics, the owner of Sequoyah Fuels, announced that it was indefinitely closing the plant and putting most of its 300 employees out of work. The facility has not operated since that time.
There is surface, subsurface, and groundwater contamination from uranium and thorium throughout the site, and uranium, thorium, and radium in raffinate sludge ponds. There is also chemical contamination of arsenic, molybdenum, and copper in the soils, which being addressed under a Resource Conservation and Recovery Act (RCRA) Administrative Order on Consent issued by EPA Region 6. The contamination was generated during the processing of uranium oxide (yellowcake) to uranium hexafluoride, from 1970 through 1992, and treatment of the process raffinate. Soil contamination levels range from about 5 Ci/g to more than 500 Ci/g of (primarily) uranium and thorium. Uranium concentration in the groundwater ranges from ~200 - 30,000 Ci/l. Radium concentration in the raffinate sludges are about 300 - 350 Ci/g. There is also process system waste comprising piping, vessels, and building materials contaminated with uranium in various chemical forms such yellowcake, uranyl nitrate, and uranium hexafluoride. The total radiological and hazardous waste volume is estimated to be 141,600-311,520 m3 (5-11 million ft3).
SFC supplied formal notice of its intent to seek license termination in accordance with 10 CFR 40.42(e) in a letter dated February 16, 1993. Based on available information, at least some of the identified waste and contamination at the site was known to exceed NRC's existing radiological criteria for decommissioning. NRC licenses these facilities under 10 CFR part 40. Specifically, the license authorizes SFC to possess up to 20 million metric tons of source material in any form. The contaminated material at the Gore site is in the form of uranium, uranium oxides, uranium fluorides, thorium, radium, and decay-chain products in process equipment and buildings, soil, sludge, and groundwater.
To address the soils, subsoils, and groundwater contaminated with uranium and thorium, the SFC submitted decommissioning plans for the site in 1998 and 1999. The SFC submitted a reclamation plan dated January 28, 2003. The reclamation was updated by submittals dated August 8, 2003, August 29, 2003, February 17, 2004, and April 12, 2005. The NRC staff was developing a draft Safety Evaluation Report (SER) and an associated Environmental Impact Statement to document its review the plan. In June 2003, the SFC submitted a ground water monitoring plan and corrective action plan, the former was approved in August 2005. The estimated date for closure is December 1, 2012.
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