Speaker
Mr
Beng Thye Tan
(University of Cambridge, Singapore Nuclear Research and Safety Initiative)
Description
The migration of radionuclides from underground nuclear waste repositories will involve the formation of uranium secondary minerals when ground water reacts with the spent nuclear fuel.
During oxic or anoxic spent fuel dissolution, amorphous phases can precede the development of well-defined crystalline mineral phases. Nuclear magnetic resonance (NMR) can probe the structure of these amorphous alteration products and trace the evolution of secondary phases.
To develop the technique, potential secondary phases of $^{17}$O-enriched uranium minerals have been fabricated to establish the oxygen environments of becquerelite, Ca(UO$_2$)$_6$O$_4$(OH).8(H$_2$O), andersonite, Na$_2$Ca(UO$_2$)(CO$_3$)3.6H$_2$O and grimselite, K$_3$Na(UO$_2$)(CO$_3$)$_3$.(H$_2$O). These contain calcium (Ca$^2+$), carbonate (CO$_3$$^{2+}$), and other ubiquitous ions.
Solid state $^{17}$O MAS-NMR spectra of uranium minerals have been obtained in a 9.39T magnetic field.
Detailed differences in oxygen local environments such as uranyl bond lengths and interlayer OH and H$_2$O can be distinguished by analyzing the spectra, which can elucidate the alteration of UO$_2$ by $^{17}$O water.
Primary author
Mr
Beng Thye Tan
(University of Cambridge, Singapore Nuclear Research and Safety Initiative)
Co-authors
Dr
Ian Farnan
(Department of Earth Sciences, University of Cambridge)
Dr
Robert J. Baker
(Trinity College, Dublin)
