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Plutonium and Neptunium Incorporation in Zirconolite

Published online by Cambridge University Press:  03 September 2012

B. D. Begg
Affiliation:
Materials Division, ANSTO, PMB 1, Menai, NSW 2234, Australia, emailb.begg@ansto.gov.au
E. R. Vance
Affiliation:
Materials Division, ANSTO, PMB 1, Menai, NSW 2234, Australia, emailb.begg@ansto.gov.au
R.A Day
Affiliation:
Materials Division, ANSTO, PMB 1, Menai, NSW 2234, Australia, emailb.begg@ansto.gov.au
M. Hambley
Affiliation:
Materials Division, ANSTO, PMB 1, Menai, NSW 2234, Australia, emailb.begg@ansto.gov.au
S. D. Conradson
Affiliation:
Los Alamos National Laboratory, New Mexico, USA
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Abstract

The incorporation of Pu and Np in zirconolite (CaZrTi2O7) has been investigated over a range of redox conditions. Zirconolite formulations designed to favour either trivalent or tetravalent Pu and Np were prepared by limiting the amount of charge compensating additives available to maintain electroneutrality. From near-edge X-ray absorption spectroscopy the Pu valence state was found to vary with the processing atmosphere, from completely tetravalent when fired in air, and located on either the Ca or Zr sites, to trivalent, when substituted on the Ca site after annealing in 3.5% H2/N2. Np was predominantly tetravalent over the range of redox conditions examined and was readily incorporated on either of zirconolite's Ca or Zr sites. The charge compensation mechanisms at work in different zirconolites are also discussed.

Type
Research Article
Copyright
Copyright © Materials Research Society 1997

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References

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