Distribution of plutonium and americium beneath the 216-Z-1A Crib: a status report

Past liquid waste disposal practices at the Hanford site have included the discharge of actinide-bearing liquid waste directly to the ground via structures termed cribs. A study to characterize the current distribution of plutonium and americium in sediments beneath one of these retired facilities, the 216-Z-1A Crib, has been conducted. To obtain distribution data, wells were drilled through and around the crib using specially developed containment and sampling techniques. Sediment samples collected during drilling were geologically characterized and analyzed for plutonium and americium content. The acquired data were used to construct geologic cross sections and isopleth cross sections of plutonium and americium concentrations with depth. Mechanisms which may have been responsible for the determined pattern of plutonium and americium distribution were also considered. 15 figures, 7 tables