Krupka K.M.,Applied Geology and Geochemistry Group |
Cantrell K.J.,Applied Geology and Geochemistry Group |
Schaef H.T.,Applied Geology and Geochemistry Group |
Arey B.W.,WR Wiley Environmental Molecular science Laboratory at PNNL |
And 3 more authors.
Characterization of actual residual wastes is needed to develop models that simulate contaminant release mechanisms from residual waste solids reacting with water infiltrating the tanks. Researchers have completed several studies characterizing wastes from various Hanford underground storage tanks using X-ray diffraction (XRD), scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and/or transmission electron microscopy (TEM). Researchers use SEM in combination with EDS and element mapping techniques to characterize the phase associations, morphologies, particle sizes, surface textures, and compositions of solid particles in the unleached and leached residual waste samples. Understanding the chemistry and dissolution rates of the co precipitated forms of iron oxides/hydroxides would provide a mechanistic approach to estimating release rates for chromium, uranium, and technetium. Moreover, the resulting mechanistic source-term models will be more scientifically defensible and less conservative, which may reduce the costs of tank-farm closure. Source