Basic Engineering Research for D&D of R. Reactor Storage Pond Sludge: Electrokinetics, Carbon Dioxide Extraction, and Supercritical Water Oxidation

Large quantities of mixed low level waste (MLLW) that fall under the Toxic Substances Control Act (TSCA) exist and will continue to be generated during D&D operations at DOE sites across the country. Currently, the volume of these wastes is 23,500 m3, and the majority of these wastes (i.e., almost 19,000 m3) consist of PCBs and PCB-contaminated materials. No proposed process for the recovery and/or destruction of these persistent pollutants has emerged as the preferred choice for DOE cleanup. Collaborating researchers at the University of South Carolina (USC), Clemson University (Clemson University), and the Savannah River Technology Center (SRTC), under the direction of the South Carolina Universities Research and Education Foundation (SCUREF), have performed initial research and development on a combined PCB extraction/destruction process for the PCB-contaminated solids that are generated during D&D activities. Extraction is performed using either supercritical carbon dioxide (CO2) or hot, pressurized water. Destruction is accomplished by oxidation in supercritical or near-critical water. Two key aspects of the proposed process are that it isolates and concentrates the PCBs from the solid matrices (thereby reducing waste volume greatly), and little if any secondary solvent or solid wastes are generated.