Reactive Transport of Uranium in Waste Plumes of Hanford Site

The overall objective of this renewal proposal is to construct an experimentally supported conceptual model of U fate and transport, during and after the tank leakage, at heavily Uncontaminated areas within the Hanford Site. Through simulating the tank leakage event in laboratory columns, we will better understand the spatial and temporal distribution of the spilled U, and its mobility. These laboratory results will specifically be used to compare with and help explain borehole data from underneath tank BX-102. Our research focuses on the following basic issues: (1) Determining the spatial distribution of U within the plume during the early stage of waste plume development. (2) Determining the forms and amount of U partitioned in the pore water relative to the matrix associated U. Identify dissolved U and suspended mobile U-rich colloids in the aqueous phase, and characterize matrix-associated forms (deposited U colloids, sorbed and precipitated U species). (3) Determine how all the above change with time. (4) Determining the mobility of U (release and transport) as function of aging. (5) Developing a mechanistic reactive transport model capable of accounting for both dissolved and particulate U(VI) in the Hanford vadose zone. An overall understanding of U-precipitation vs. adsorption, stability of nanoparticles and their transport, will improve our ability to predict current and future development of U-waste plumes