Microscopic Controls on the Desorption/Dissolution of Sorbed U(VI) and Their Influence on Reactive Transport

A sizable groundwater U plume exists in Hanford's 300 A resulting from the disposal of fuel rod dissolution wastes containing Al, Cu, and U to the vadose zone. This project is studying U-contaminated samples collected along a flow path from the waste source to the Columbia River. Three primary objectives are being pursued: (1) To develop microscopic models for U desorption/adsorption in sediments along the flow path including both geochemical reaction and diffusive mass transport processes. (2) To parameterize the microscopic models with appropriate laboratory measurements and data within context of a dual continuum, reactive transport model (DCM). (3) To apply the parameterized DCM to laboratory columns of different size and sediment texture for testing of scaling hypotheses