Conversion of mixed waste to radioactive waste: a case study

As part of the US Department of Energy's (DOE) Formerly Utilized Sites Remedial Action Program (FUSRAP), Bechtel National performed remedial actions at the National Guard Armory (NGA) in Chicago, Illinois. The scope of FUSRAP includes sites such as the NGA which were used for uranium storage and processing under the jurisdiction of the Manhattan Engineer District and the Atomic Energy Commission during the development and the nation's atomic energy program. During remedial actions at the NGA, sixteen 55-gallon (208-liter) drums of sludge were removed from catch basins and drain lines in the garage area of the Armory. This sludge was contaminated with uranium-238 at concentrations up to 14,000 picoCuries per gram as a result of the aforementioned uranium processing. The sludge also contained lead and several volatile organic compounds. Several options for disposing of the sludge were explored; treatment and disposal at existing radioactive waste disposal sites, incineration, supercritical water oxidation, and microwave treatment. Each of these options however was eliminated due to cost, technical feasibility, and/or regulatory restrictions. As a result, bench scale tests were conducted on samples of the sludge to identify techniques for separating the chemical and radiological hazards so the sludge could be disposed. Thermal treatment was selected for field implementation when bench scale thermal tests raised the flash point of a sample of sludge to above 800 degree F (426.7 C), well above the RCRA criterion