Geological Society of America

T256 Investigations of Hydrothermal Systems: Advances and Challenges (Posters)

Wednesday, 25 September 2019
9:00 AM - 6:30 PM
Hall AB, North Building

SPECIATION, STABILITY AND MOBILITY OF URANIUM AND THORIUM IN HYDROTHERMAL ENVIRONMENTS

Paper number: T256-14
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Hongwu Xu Presenting Author
Los Alamos National Laboratory, Los Alamos, NM
Artaches Migdissov
Los Alamos National Laboratory, Los Alamos, NM
Hakim Boukhalfa
Los Alamos National Laboratory, Los Alamos, NM
Robert Roback
Los Alamos National Laboratory, Los Alamos, NM
Robert Mayanovic
Missouri State University, Springfield, MO

Abstract

Understanding dissolution, speciation and reactivity of actinide-bearing phases in water-mediated processes at elevated temperature (T) and pressure (P) conditions is critical for tackling a range of issues in actinide science and technology from disposal of high-level nuclear wastes in a geological repository to development of robust accident-tolerant nuclear fuels. Despite the importance, studies of the interactions of actinides with water at elevated T/P are scarce. In this presentation, we will highlight our recent studies on speciation and stability of U/Th in aqueous solutions containing different ligands (chloride, sulfate) at high T/P using a suite of techniques including solubility measurements, synchrotron X-ray absorption, UV-Vis and Raman spectroscopy, combined with the autoclave or hydrothermal diamond-anvil cell technique. Our results demonstrate that the neutrally charged U/Th-ligand species are highly stable at hydrothermal conditions, and U (IV) and Th (IV) - traditionally considered to be immobile - become highly mobile in hydrothermal environments.

Geological Society of America Abstracts with Programs. Vol. 51, No. 5

doi: 10.1130/abs/2019AM-337518

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