Preliminary data on the occurrence of transuranium nuclides in the environment at the radioactive waste burial site Maxey Flats, Kentucky

Between 1963 and 1974 approximately 104000 m3 of solid 'low-level' radioactive waste were buried at the Maxey Flats, Kentucky, site. These wastes contained approximately 80 kg of plutonium-239 and a large undetermined quantity of other plutonium isotopes. In 1972 elevated levels of radioactivity were detected in monitoring samples collected near the burial facility by the Kentucky Department for Human Resources (KDHR). Subsequently, the KDHR conducted a special radiological study of the burial site and its environs. Based on the concentration of plutonium present or the ratio of plutonium-238 to -239, 49 of 50 samples collected on or near the burial site were contamined with plutonium from a source other than atmospheric fall-out. Plutonium was detected in surface soil, in soil cores 90 cm deep, in monitoring wells and in streams that drain the site. During the past 13 years infiltrating precipitation collected in the burial trenches, forming a mobile plutonium-contaminated leachate. The chemical form, pathways and mechanisms by which the plutonium moved out of the trenches have not been explained satisfactorily. Extensive studies of the burial site are in progress. The primary conclusion drawn from the hydrogeology of the site and the plutonium data is that plutonium has moved from the facility; possibly via several pathways including surface water runoff, atmospheric fall-out from an evaporator, lateral migration through the soil, and migration through jointed subsurface geologic formations. The paper presents the plutonium data with a commentary on its occurrence and possible significance from a hydrogeological and environmental perspective. (author)