Abstract
The corrosion mechanisms and kinetics of a Mg-rich alkali aluminoborosilicate glass simulating UK high-level waste (CaZn28) were investigated upon dissolution in synthetic cement solutions. Dissolution varied as a function the different pH and alkali/alkaline earth content of each cement solution. High resolution microscopy and spectroscopy techniques ascertained the nature of the interface between the glass and the cement solutions. TEM-EDS revealed alkali- and alkaline earth-rich silica gels, into which K, Ca and Mg were incorporated. TEM-SAED, combined with synchrotron micro-focus XRD, identified the ubiquitous precipitation of the Mg-aluminate layered double hydroxide phase, meixnerite (Mg6Al2(OH)18·4H2O), in addition to goethite (FeOOH) and crystalline silica. The C-S-H phase, tobermorite (Ca5Si6O16(OH)2·4H2O), was identified in the most Ca-rich solution only. These data give insight to the role of alkali/alkaline earth-rich solutions in the dissolution or radioactive waste glasses, of importance to the final disposition in a geological disposal facility.
Original language | English |
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Article number | 67 |
Journal | npj Materials Degradation |
Volume | 6 |
Issue number | 1 |
DOIs | |
State | Published - Dec 2022 |
Funding
CLC and CLT wish to acknowledge the Engineering and Physical Science Research Council (EPSRC) for fellowship funding under grant awards EP/N017374/1 and EP/G037140/1, respectively. EPSRC is further acknowledged for funding under the Nuclear FiRST Centre for Doctoral Training (EP/S012400/1). This research utilised the HADES/MIDAS and PLEIADES National Nuclear User Facilities at the University of Sheffield, established with financial support from EPSRC and BEIS, under grant numbers EP/T011424/1 and EP/V035215/1. The portions of the research conducted at Oak Ridge National Laboratory (ORNL) were supported by the US Department of Energy’s Office of Environmental Management (EM) Tank Waste Management program. ORNL is operated by UT-Battelle, LLC for the US DOE under Contract No. DE-AC05-00OR22725. Parts of this research used the XFM Beamline of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No. DE-SC0012704. We are grateful to Professor Neil Hyatt for early input to this work, to Dr. Mike Harrison at the National Nuclear Laboratory for provision of glass materials, to Dr. Karine Ferrand at SCK.CEN for support and advice with synthesis of synthetic cement waters and to Dr. Seb Lawson for assistance with SAED diffraction pattern analysis. The µ-XRD data collection was assisted by the Beastie Boys. For the purposes of open access, the author has applied a Creative Commons Attribution (CC BY) licence to any Author Accepted Manuscript version arising.