Stabilization of multiple mixed waste streams from Oak Ridge DOE sites

IT was contracted to assist in designing and performing a statistically based series of treatability studies on stabilization and solidification of various waste streams from DOE`s Oak Ridge Reservation. The waste streams were generated by a variety of processes used in the manufacture of nuclear weapon components and fuel. The treatability studies were designed to provide information on the effects of various quantities of stabilization reagents on the characteristics of the final waste form. Primary performance criteria were no free liquid and meet or exceed LDR leachability levels at 28-day cure. Secondary performance criteria were various implementability parameters. Characteristics monitored were unconfined compressive strength (UCS), rate of set, free liquids, metals leachability, unit weight, and radionuclide leachability. Stabilization reagents used in the study included Portland cement, fly ash, perlite, and blast furnace slag. Twenty formulations were tested for each waste stream. These formulations are statistical extreme vertices desired that was formulated by PNL. Oak Ridge National Laboratory (Energy Systems) and IT were conducting parallel programs on different waste streams. A standardized set of test procedures and stabilization reagents were used by IT and Energy Systems. By design formulations were determined that failed and met all primary and secondary performance criteria.more » The 28-day cured waste-grout mixtures had the consistency ranging form pudding-like to soil-like to monoliths with UCS greater than 5000 psi. Generally, formulations that were monoliths with greater than 100 psi compressive strength had lower leachabilities and liquid bleed. The effect of waste chemical composition on the leachability is discussed.« less