Characterization of airborne radionuclide particulates in ventilated liquid-waste tanks

Tank vapor spaces in selected underground double-wall tanks at the US Dept. of Energy Hanford site have been sampled to characterize airborne radionuclides present in the form of particulates or aerosols. Nine underground tanks containing liquid radioactive wastes were sampled. These tanks are actively ventilated and are kept under negative pressure. The vent gases that contain the particulates are drawn through high-efficiency particulate air (HEPA) filters prior to sampling and discharging to the environment. Quantification of airborne radioactive particulates in these operating tanks is important in the development of credible accident scenarios for safety analyses. The data are also useful for estimating HEPA filter effectiveness.