Characterization of Sr and Cs sequestration and mineral transformation from reaction of Hanford sediments and caustic waste

GEOC 124

Sunkyung Choi, schoi@ucmerced.edu1, Jon Chorover, chorover@cals.arizona.edu2, Geoffrey Bowers, gmb189@psu.edu3, Caleb Strepka, crs274@psu.edu3, Karl T. Mueller, ktm2@psu.edu3, Nelson A. Rivera, nrivera@ucmerced.edu1, and Peggy A. O'Day, poday@ucmerced.edu1. (1) School of Natural Sciences, University of California, Merced, CA 95344, (2) Department of Soil, Water and Environmental Science, University of Arizona, Shantz 429, Building #38, Tucson, AZ 85721, (3) Department of Chemistry, Pennsylvania State University, University Park, PA 16802
Large volumes of high-level radioactive waste have leaked into the underlying sediment at the Hanford Site (WA). Along with radioactive elements, highly alkaline (pH 13), high ionic strength fluids have reacted with sediments to generate a complex history of mineral alteration, fluid evolution, and waste dispersion. Uncontaminated Hanford sediments were reacted with synthetic tank waste leachate in batch laboratory experiments to examine Sr and Cs sequestration with aging time (1 d to 1 yr). Reaction products were characterized by bulk and microfocused XAS and XRD, SEM/EDS, HRTEM, DRIFT, Si or Al NMR, and TG/DTA. The type and amount of clay minerals in Hanford sediments influenced secondary mineral transformation based on similar experiments using specimen clays. Neoformed sodalite and cancrinite play an important role in the irreversible sequestration of Sr, but uptake by multiple primary or neoformed phases varies among different sediments and specimen clays, with different degrees of reversible contaminant binding.
 

Physical Chemistry of Soil and Aquifer Systems: A Symposium in Honor of Garrison Sposito
1:30 PM-4:40 PM, Wednesday, 13 September 2006 Moscone Center -- Room 256, Oral

Division of Geochemistry

The 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006