| About this Abstract |
| Meeting |
MS&T21: Materials Science & Technology
|
| Symposium
|
Emergent Materials under Extremes and Decisive In Situ Characterizations
|
| Presentation Title |
In-Situ Synchrotron X-ray Absorption Spectroscopic Investigations of Actinide Speciation under Hydrothermal Conditions |
| Author(s) |
Robert Mayanovic, Jason Baker, Diwash Dhakal, Nadib Akram, Xiaofeng Guo, Hakim Boukhalfa, Cheng-Jun Sun, Hongwu Xu |
| On-Site Speaker (Planned) |
Robert Mayanovic |
| Abstract Scope |
Investigations of actinide behavior in high P-T aqueous fluids are critical to addressing issues concerning high-level waste disposal, transport of uranium after nuclear accidents and development of accident-tolerant nuclear fuels. In-situ studies of actinide complexation in high P-T aqueous fluids containing ligands such as Cl- and CO32- are required for an accurate assessment of the solubility, stability and speciation of actinides in high P-T-γ (γ: radiation) extreme environments. Here we present our in-situ U L-III edge X-ray absorption spectroscopy (XAS) measurements of uranyl chloride and uranyl carbonate aqueous solutions using the hydrothermal diamond anvil cell (HDAC), at temperatures up to 500 °C. XAS spectral analysis reveals a trend toward charge neutral uranyl chloride complex species with increasing temperatures whereas uranyl carbonate complexes are found to be stable only to ~ 100 °C, in aqueous solutions. This is confirmed in our in-situ Raman measurements made on the same systems. |