Structural characterization of uranium and lanthanide loaded borosilicate glass matrix
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View abstract on PubMed
Summary
This summary is machine-generated.Borosilicate glass was studied for radioactive waste conditioning. Uranium and actinides, like cerium, neodymium, and europium, were added, affecting the glass structure and increasing dissolution.
Area Of Science
- Materials Science
- Nuclear Engineering
- Geochemistry
Background
- Borosilicate glass is a promising material for immobilizing high-level radioactive waste.
- Understanding the structural and chemical behavior of actinides within glass matrices is crucial for waste containment.
- Lanthanides serve as chemical surrogates for trivalent actinides in experimental studies.
Purpose Of The Study
- To investigate the structural and chemical effects of co-incorporating uranium and lanthanide oxides into borosilicate glass.
- To evaluate the influence of these elements on the glass network and their leachability.
- To assess the suitability of borosilicate glass for conditioning waste containing uranium and actinides.
Main Methods
- Simultaneous loading of UO3 and lanthanide oxides (CeO2, Nd2O3, Eu2O3) into a borosilicate glass matrix.
- Neutron diffraction and Reverse Monte Carlo (RMC) simulations for structural analysis.
- X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) for chemical state and depth profiling.
- Leaching tests to assess material durability.
Main Results
- The glass structure is primarily composed of SiO4 and BO3/BO4 units.
- Cerium exists mainly as Ce(III), while uranium is present as a mixture of U(V) and U(VI).
- Uranium acts as an intermediate oxide, decreasing the coordination of boron.
- Lanthanide ions function as network modifiers, promoting a shift in boron coordination from 3 to 4 with increasing concentration.
- XPS revealed depth-dependent variations in the U(IV)/U(VI) ratio.
- Leaching tests indicated increased dissolution of Si, B, and Na compared to the pristine glass matrix.
Conclusions
- The incorporation of uranium and lanthanides significantly alters the structure and chemical state within the borosilicate glass.
- The observed changes in boron coordination and uranium speciation have implications for glass stability and long-term performance.
- Increased leaching of network formers and modifiers suggests potential challenges for waste containment under certain conditions.
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