| About this Abstract |
| Meeting |
MS&T22: Materials Science & Technology
|
| Symposium
|
Emergent Materials under Extremes and Decisive In Situ Characterizations
|
| Presentation Title |
In-Situ X-ray Absorption Spectroscopy of Actinide Speciation in Aqueous Fluids at Extreme 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 |
There are scarce data on the molecular structure and stability of aqueous actinide species at high P-T conditions. Such data are critical for development of accident-tolerant fuels and to address issues pertaining to high-level waste disposal. In-situ X-ray absorption spectroscopy (XAS) and related spectroscopic studies of actinide species in aqueous fluids, containing chloride, carbonate and other ligands, are needed to determine the stability and speciation of actinides under high P-T-γ (γ: radiation) conditions. Our in-situ U LIII edge XAS investigations of uranyl chloride and uranyl carbonate aqueous solutions, at temperatures from 25 to 500 °C, will be discussed. The XAS measurements are made using the hydrothermal diamond anvil cell housed in a 3-layer containment. Analysis of the XAS data confirms that the aqueous uranyl chloride complexes trend toward charge neutral species with increasing temperatures. Conversely, our analysis shows that the uranyl carbonate complexes are stable only to ~ 100 °C. |