Technical Evaluation of Remediation Technologies for Plutonium-Contaminated Soils at the Nevada Test Site (Nts)

Abstract

The Clemson Environmental Technologies Laboratory (CETL) was contracted by the National Energy Technology Center to evaluate technologies that might be used to reduce the volume of plutonium-contaminated soil at the Nevada Test Site.The project has been systematically approached.A thorough review and summary was completed for:1) The NTS soil geological, geochemical and physical characteristics 2) The characteristics and chemical form of the plutonium that is in these soils 3) Previous volume reduction technologies that have been attempted on the NTS soils 4) Vendors with technology that may be applicable 5) Related needs at other DOE sites Soils from the Nevada Test Site were collected and delivered to the CETL. Soils were characterized for Pu-239/240, Am-241 and gross alpha. In addition, wet sieving and the subsequent characterization were performed on soils before and after attrition scrubbing to determine the particle size distribution and the distribution of Pu-239/240 and gross alpha as a function of particle size. Sequential extraction was performed on untreated soil to provide information about how tightly bound the plutonium was to the soil. Magnetic separation was performed to determine if this could be useful as part of a treatment approach.Using the information obtained from these reviews, three vendors were selected to demonstration their volume reduction technologies at the CETL. Two of the three technologies, bioremediation and soil washing, met the performance criteria. Both were able to significantly reduce the concentration plutonium in the soil from around 1100 pCi/g to 200 pCi/g or less with a volume reduction of around 95%, well over the target 70%. These results are especially encouraging because they indicate significant improvement over that obtained in these earlier pilot and field studies. Additional studies are recommended.