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Uranium Release from Acidic Weathered Hanford Sediments: Single-Pass Flow-Through and Column Experiments

The reaction of acidic radioactive waste with sediments can induce mineral transformation reactions that, in turn, control contaminant fate. Here, sediment weathering by synthetic uranium-containing acid solutions was investigated using bench-scale experiments to simulate waste disposal conditions at Hanford’s cribs (Hanford, WA). During acid weathering, the presence of phosphate exerted a strong influence over uranium mineralogy and a rapidly precipitated, crystalline uranium phosphate phase (meta-ankoleite [K(UO2)(PO4)·3H2O]) was identified using spectroscopic and diffraction-based techniques. In phosphate-free system, uranium oxyhydroxide minerals such as K-compreignacite [K2(UO2)6O4(OH)6·7H2O] were formed. Single-pass flow-through (SPFT) and column leaching experiments using synthetic Hanford pore water showed that uranium precipitated as meta-ankoleite during acid weathering was strongly retained in the sediments, with an average release rate of 2.67 × 10–12 mol g–1 s–1. In the absence of phosphate, ...

Authors:   Guohui Wang; Wooyong Um; Zheming Wang; Estela Reinoso-Maset; Nancy M. Washton; Karl T. Mueller; Nicolas Perdrial; Peggy A. O’Day; Jon Chorover
Journal:   Environmental Science & Technology
Year:   2017
DOI:   10.1021/acs.est.7b03475
Publication date:   21-Sep-2017
Facts, background information, dossiers
  • radioactive waste
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