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Neptunium-Doped Synroc: Partitioning, Leach Data and Secondary Phase Development

Published online by Cambridge University Press:  15 February 2011

Katherine L. Smith,
Mark G. Blackford,
Gregory R. Lumpkin,
Kaye P. Hart and
Brett J. Robinson
Katherine L. Smith
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia.
Mark G. Blackford
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia.
Gregory R. Lumpkin
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia.
Kaye P. Hart
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia.
Brett J. Robinson
Affiliation:
Advanced Materials Program, Australian Nuclear Science and Technology Organisation, Private Mail Bag 1, Menai, NSW 2234, Australia.
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Abstract

Np-doped Synroc was subjected to modified MCC-1 leach tests in demineralised water at 70°C. Normalised total differential Np leach rates were about 10−4 g m−2 d−1 initially, decreased to about 10−5 g m−2 d−1 after 60 days and stayed approximately constant for periods totalling up to 2283 d. Scanning electron microscope (SEM) and analytical transmission electron microscope (AEM) examination of discs leached for periods totalling 56 d or longer showed that they were covered with crystalline anatase, brookite and ilmenite. The crystalline secondary phases initially nucleated in polishing scratches and on perovskite grains. However, after leaching for a total of 422 d most of the surface was covered. None of the secondary phases contained observable amounts of Np (< 0.2 wt%). These data are discussed in relation to previous work.

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References

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