The structural role of Zr within alkali borosilicate glasses for nuclear waste immobilisation |
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| Authors: | AJ Connelly KP Travis ER Maddrell |
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| Institution: | a Immobilisation Science Laboratory, Department of Materials Science and Engineering, Sir Robert Hadfield Building, Mappin Street, University of Sheffield, S1 3JD, UKb National Nuclear Laboratory Ltd., Sellafield, Seascale, Cumbria, CA20 1PG, UK |
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| Abstract: | Zirconium is a key constituent element of High Level nuclear Waste (HLW) glasses, occurring both as a fission product and a fuel cladding component. As part of a wider research program aimed at optimising the solubility of zirconium in HLW glasses, we have investigated the structural chemistry of zirconium in such materials using X-ray Absorption Spectroscopy (XAS). Zirconium K-edge XAS data were acquired from several inactive simulant and simplified waste glass compositions, including a specimen of blended Magnox/UO2 fuel waste glass. These data demonstrate that zirconium is immobilised as (octahedral) six-fold coordinate ZrO6 species in these glasses, with a Zr-O contact distance of 2.09 Å. The next nearest neighbours of the Zr species are Si at 3.42 Å and possibly Na at 3.44 Å, no next nearest neighbour Zr could be resolved. |
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| Keywords: | XAS Glass Zirconia Nuclear Borosiliate |
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