Characterization of hazardous constituents in HLW supernate and implications for solid LLW generation

High Level Waste (HLW) generated during Separations processing in the F- and H-Canyons is transferred to the Tank Farms for stage in 51 underground, million gallon storage tanks. The waste is an aqueous solution containing dissolved sodium salts and insoluble metal oxides/hydroxides. The waste solution is evaporated to reduce the volume, and the resulting saltcake and residual supernate are stored. Over the 40 year history of the Tank Farm, routine supernate sampling has been conducted in support of the primary goal of safe storage of HLW. As a result of routine and non-routine activities that are part of managing these highly radioactive wastes, secondary solid waste is generated. Radioactive contamination of over 90% of the solid waste generated is due to contact with BLW supernate or saltcake. In order to comply with the Waste Acceptance Criteria (WAC) for of solid waste in the E-Area Vaults (EAV), the quantity of certain radioisotopes must be manifested for each waste container and a declaration made of whether or not the waste is hazardous. However, solid waste is not amenable to routine analysis, this forces a reliance on analytical data from supernate samples to characterize the contamination. To provide the manifest information, process knowledge in combination with the limited amount of analytical data will be used. This report documents the characterization of hazardous components in the HLW supernate associated with the waste storage, evaporation and sludge processing facilities. The hazardous constituents of HLW are identified and the fate of the constituents is tracked based on knowledge of each phase of the process. The limited amount of sample data that includes analyses for hazardous species is then used to establish average and maximum characterization values. Finally, a screening based on an average supernate is compared to the criteria for the individual streams to evaluate the amount of conservatism introduced for the individual streams