Identification and Decomposition of Uranium Oxychloride Phases in Oxygen-Exposed UCl 3 Salt Compositions

• Published in: The journal of physical chemistry. B Vol. 127; no. 27; pp. 6091 - 6101
• Main Authors: Tuffy, Benjamin W, Birkner, Nancy R, Schorne-Pinto, Juliano, Davis, Ryan C, Mofrad, Amir M, Dixon, Clara M, Aziziha, Mina, Christian, Matthew S, Lynch, Timothy J, Bartlett, Maxwell T, Besmann, Theodore M, Brinkman, Kyle S, Chiu, Wilson K S
• Format: Journal Article
• Language: English
• Published: United States 13.07.2023
• ISSN: 1520-6106; 1520-5207
• DOI: 10.1021/acs.jpcb.2c09050

Complementary X-ray absorption fine structure (XAFS) spectroscopy and Raman spectroscopy studies were conducted on several UCl concentrations in several chloride salt compositions. The samples were 5% UCl in LiCl (S1), 5% UCl in KCl (S2), 5% UCl in LiCl-KCl eutectic (S3), 5% UCl in LiCl-KCl eutectic (S4), 50% UCl in KCl (S5), and 20% UCl in KCl (S6) molar concentrations. Sample S3 had UCl sourced from Idaho National Laboratory (INL), and all other samples were UCl sourced from TerraPower. The initial compositions were prepared in an inert and oxygen-free atmosphere. XAFS measurements were performed in the atmosphere at a beamline, and Raman spectroscopy was conducted inside a glovebox. Raman spectra were able to confirm initial UCl . XAFS and later Raman spectra measured, however, did not correctly match the literature and computational spectra for the prepared UCl salt. Rather, the data shows some complex uranium oxychloride phases at room temperature that transition into uranium oxides upon heating. Oxygen pollution due to failure of the sealing mechanism can result in oxidation of the UCl salts. The oxychlorides present may be both a function of the unknown O exposure concentration, depending on the source of the leak and the salt composition. Evidence of this oxychloride claim and its subsequent decomposition is justified in this work.