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Microchemical and crystallographic characterisation of fluorite-based ceramic wasteforms

Published online by Cambridge University Press:  21 March 2011

Martin C. Stennett
Affiliation:
Immobilisation Science Laboratory (ISL), Dept. of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD., UK
Neil C. Hyatt
Affiliation:
Immobilisation Science Laboratory (ISL), Dept. of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD., UK
Ewan R. Maddrell
Affiliation:
Nexia Solutions (formerly BNFL/NSTS), B170, Sellafield, Seascale, Cumbria, CA20 1PG, UK
Fergus G. F. Gibb
Affiliation:
Immobilisation Science Laboratory (ISL), Dept. of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD., UK
Guenter Moebus
Affiliation:
Immobilisation Science Laboratory (ISL), Dept. of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD., UK
William E. Lee
Affiliation:
Immobilisation Science Laboratory (ISL), Dept. of Engineering Materials, Sir Robert Hadfield Building, Mappin Street, Sheffield, S1 3JD., UK
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Abstract

A number of possible options have been proposed for the encapsulation and immobilisation of long lived actinide (Act) fractions in nuclear waste. Ceramics offer superior durability against chemical migration and the ability to be tailored to accommodate a variety ofdifferent waste streams. Research on the fabrication of dense, durable crystalline matrices for the safe disposal of fissile plutonium is ongoing and this study reports quantitative chemical, structural and spectroscopic analysis on fluorite based host phases.

Ceramics based on the fluorite structure are known to be able to incorporate a variety of actinides and in this work two candidate ceramic matrices were investigated: a pyrochlore, Gd2Zr1.60Ce0.20Hf0.20O7; and a zirconolite, (Ca0.90Gd0.10)(Zr0.50Ce0.20Hf0.20Gd0.10)Ti2O7. The chemical compositions of the two major phases observed in the ‘zirconolite’ sample were consistent with the 2M and 4M zirconolite polytypes and the presence of the 4M structure was confirmed by Electron Diffraction (ED). The major phase in the ‘pyrochlore’ ceramic was confirmed by ED to have the pyrochlore structure. Electron Energy Loss Spectroscopy (EELS) data indicated the presence of both Ce3+ and Ce4+ in all the samples.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

REFERENCES

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