Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Engineering
Modeling Complex Oxides: Thermochemical Behavior Of Nepheline-Forming Na-Al-Si-B-K-Li-Ca-Mg-Fe-O And Hollandite-Forming Ba-Cs-Ti-Cr-Al-Fe- Ga-O Systems, Stephen A. Utlak
Modeling Complex Oxides: Thermochemical Behavior Of Nepheline-Forming Na-Al-Si-B-K-Li-Ca-Mg-Fe-O And Hollandite-Forming Ba-Cs-Ti-Cr-Al-Fe- Ga-O Systems, Stephen A. Utlak
Theses and Dissertations
High concentrations of Na2O and Al2O3 in the liquid high-level radioactive waste (HLW) stored at the Hanford Site can cause nepheline (NaAlSiO4) to precipitate in a vitrified monolithic waste form upon cooling. Nepheline phase formation removes glass- former SiO2 and -modifier Al2O3 from the immobilization matrix in greater proportion to alkalis, which can reduce glass durability and consequently increase the leach rate of radionuclides into the surrounding environment.
Current uncertainty in defining the HLW glass composition region prone to precipitating nepheline necessitates targeting a conservative waste loading, which raises operational costs by extending the liquid radioactive waste disposal mission and …
Thermodynamic Modeling Of Uranium And Oxygen Containing Ternary Systems With Gadolinium, Lanthanum, And Thorium, Jacob Wesley Mcmurray
Thermodynamic Modeling Of Uranium And Oxygen Containing Ternary Systems With Gadolinium, Lanthanum, And Thorium, Jacob Wesley Mcmurray
Doctoral Dissertations
The CALPHAD method is used to assess the thermodynamic properties and phase relations in the U-M-O system where M = Gd, La, and Th. A compound energy formalism (CEF) model for fluorite UO2±x [urania] is extended to represent the complex U1-yMyO2±x [urania solid solution] phases. The lattice stabilities for fictive GdO2 [gadolinia] and LaO2 [lanthana] fluorite structure compounds are calculated from density functional theory (DFT) for use in the CEF for U1-yMyO2±x [urania solid solution phase] while U6+ [uranium 6 plus cation] is introduced into the …