A comprehensive listing of thorium shipments from the Fernald Site during the period 1952 through 1985 (Thorium Shipments, 1952-1985, p. 109) documents shipments of small quantities of thorium metal (less than 15 kg each) to Metals and Controls Corp. in June 1955, February 1957, and October 1957. Documentation of another thorium shipment (this time involving Brookhaven National Laboratory and Argonne National Laboratory) is available for a June 1957 shipment (Huke, 1954). A 1957 uranium exposure assessment, conducted by the Environmental Measurement Laboratory, lists the production of thorium foils as one of the processes at Metals and Controls Corp. (AEC, 1957). The only definitive information on the amount of thorium at Metals and Controls Corp. is from a 1962 nuclear safety analysis that lists the total quantity of thorium as 244 kg (ASTRA, 1962).
Waste handling, processing of scrap metal and residues, and treatment of waste acids and water were conducted inside Building 5 and outside Building 5 in areas known as the Metals Recovery Area and the Stockade. A waste evaporator and an incinerator were operated in Building 5 and the adjacent Metals Recovery Area. Scrap and waste generated in the manufacturing processes were returned to the U.S. Government; however, some materials contaminated with low levels of radioactivity were buried onsite adjacent to Building 11.
Following cessation of fuel fabrication operations in 1981, TI initiated remediation of uranium contamination in the buildings and surrounding exterior locations. Remediation and final surveys of contaminated portions of Buildings 4 and 10 were completed in 1985, and the NRC staff approved release of these buildings for unrestricted use. Residual radioactive contamination remained in the burial area east of Building 11 and west of the relatively recently-constructed Building 12. Initial remediation of the burial area was completed in December 1992. A confirmatory survey conducted by the Oak Ridge Institute for Science and Education (ORISE) in December 1992 identified some remaining contamination on the walls of the excavation. In July 1993, the licensee completed additional remediation activities. An ORISE confirmatory survey in December 1993 did not identify any remaining residual contamination in the burial area in excess of the NRC criteria for release for unrestricted use (NRC, 1997).
Records indicate that Metals and Controls Corp. fabricated fuel elements for production reactors, but it is unclear whether its work was related to the nuclear weapons complex. For example, Metals and Controls Corp. fabricated uranium foils for reactor experiments and fuel components, fabricated complete reactor cores for the Naval Reactors program, and fabricated uranium fuel elements for experimental and research reactors. Records indicate shipments of depleted uranium between Rocky Flats and Metals and Controls Corp. during the period from 1955 to 1958 (Uranium Shipments, 1955-1958). Table 4-1 shows process information for Metals and Controls Corp.
In the company’s license termination request, only Buildings 3, 4, and 10 are noted as having been used in radioactive material processing (TI, 1982). Subsequent correspondence indicates that the potentially-impacted area was expanded to include Buildings 1, 5, 11, and the outside areas around Buildings 11 and 12 (Survey, 1997; Remediation, 1996). Based on this information, these are the only areas associated with radiological operations. Except as noted in Table 4-1 for Building 10, NIOSH has very limited information describing any access control practices at the Metals and Controls Corp. site; thus, NIOSH is unable to determine which workers may or may not have entered the identified radiological areas.