Radioisotopic composition of yellowcake: an estimation of stack release rates

Abstract

Uranium concentrate (yellowcake) composites from four mills (Anaconda, Kerr-McGee, Highland, and Uravan) were analyzed for U-238, U-235, U-234, Th-230, Ra-226 and Pb-210. The ratio of specific activities of U-238 to U-234 in the composites suggested that secular radioactive equilibrium exists in the ore. The average activity ratios in the yellowcake were determined to be 2.7 x |0-3 (Th-230/U-238), 5 * \0~h (Ra-226/U-238) and 2 x lO" 1 * (Pb-2IO/U-238). Based on earlier EPA measurements of the release rates from the stacks, the amount of yellowcake released was determined to be 0.\% of the amount processed. The purpose of this study was to characterize yellowcake by its radioisotopic composition and estimate the release rate from stacks and packaging operations. Accordingly, samples were obtained from the following uranium mills: Anaconda Company (Grants, NM), Kerr-McGee Nuclear Corporation (Grants, NM), Union Carbide (Uravan, CO) and Exxon (Douglas, WY). These mills process the major portion of uranium mined in the United States and also represent the different geographical uranium-producing regions. Their processing characteristics are summarized below and have been previously reported in detail by Merritt (1971), Guccione (1974) and Coleman (1978). Anaconda Company, Bluewater, NM Leaching: Sulfuric acid and Mn02 Uranium Separation: Resin-in-pulp ion exchange (IRA-430 anion exchange resin with FeSO^ and MgO) to January 1, 1978. The process for extraction was changed to solvent extraction after an expansion in 1978.