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The Long-Term Corrosion Behavior of Titanate Ceramics for Pu Disposition: Rate-Controlling Processes

Published online by Cambridge University Press:  10 February 2011

A. J. Bakel ,
C. J. Mertz ,
M. C. Hash  and
D. B. Chamberlain
A. J. Bakel
Affiliation:
Argonne National Laboratory, Chemical Technology Division, 9700 S. Cass Avenue, Argonne, IL60439
C. J. Mertz
Affiliation:
Argonne National Laboratory, Chemical Technology Division, 9700 S. Cass Avenue, Argonne, IL60439
M. C. Hash
Affiliation:
Argonne National Laboratory, Chemical Technology Division, 9700 S. Cass Avenue, Argonne, IL60439
D. B. Chamberlain
Affiliation:
Argonne National Laboratory, Chemical Technology Division, 9700 S. Cass Avenue, Argonne, IL60439
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Abstract

The aqueous corrosion behavior of a zirconolite-rich titanate ceramic was investigated with the aim of describing the rate-controlling process or processes. This titanate ceramic is similar to SYNROC and is proposed as immobilization materials for surplus Pu. The corrosion behavior was described with results from MCC-I and PCT-B static dissolution tests. Three important observations were made: a) Ca is released at a constant rate [7×10−5 g/(m2 day)] in PCT-B tests for up to two years; b) the leachates from PCT-B tests are saturated with respect to both rutile and anatase, and c) the release rates for Pu and Gd increase with time (up to two years) in PCT-B tests. The first observation suggests that the ceramics continue to corrode at a low rate for at least 2 years in PCT-B tests. The second observation suggests that the approach to saturation with respect to these TiO2 phases does not limit the corrosion rate in PCT-B tests. The third observation suggests that the release rate of Pu and Gd are controlled by some unique process or processes, i.e., some process or processes that do not affect the release rate of other elements. While these processes cannot be fully described at this point, two possible explanations, alteration phase formation and grain boundary corrosion are forwarded.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 608: Symposium QQ – Scientific Basis for Nuclear Waste Management XXIII , 1999 , 387
Copyright
Copyright © Materials Research Society 2000

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References

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