TC-99 REMOVAL FROM PROCESS SOLUTIONS AND CONTAMINATED GROUNDWATER

The predominant form of technetium under oxic conditions is the pertechnetate anion (TcO4-), which is highly soluble in water and readily mobile in the environment. Technetium-99 is of particular concern because of its persistence and mobility. Various equipment decontamination and uranium recovery operations at the Portsmouth Gaseous Diffusion Plant generate a ''raffinate'' waste stream characterized by toxic heavy metals, high concentration of nitric acid, and low levels of radionuclides (U-235 and Tc-99). Dilution and adjustment of solution pH to a value of 8.2 to 8.5 precipitates a heavy-metals-sludge and a filtrate. The removal of Tc-99 from these waste streams and from contaminated groundwater can be accomplished using anionic ion-exchange resins. Batch equilibrium and packed column breakthrough and regeneration studies were performed using inorganic sorbents and organic ion-exchange resins (Dowex SRB-OH and Reillex resins). These studies were performed on actual and surrogate raw raffinates, filtrates, and surrogate groundwater samples. The experimental conditions were chosen to closely represent the actual process.