Hostname: page-component-848d4c4894-mwx4w Total loading time: 0 Render date: 2024-06-30T13:11:17.381Z Has data issue: false hasContentIssue false
  • English
  • Français

Atmosphere Processing Effects on Titanate Ceramics Designed for Plutonium Disposition

Published online by Cambridge University Press:  21 March 2011

M.W.A. Stewart ,
E.R. Vance ,
A. Jostsons ,
K. Finnie ,
R.A. Day  and
B.B. Ebbinghaus
M.W.A. Stewart
Affiliation:
Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1, Menai, NSW 2234, Australia
E.R. Vance
Affiliation:
Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1, Menai, NSW 2234, Australia
A. Jostsons
Affiliation:
Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1, Menai, NSW 2234, Australia
K. Finnie
Affiliation:
Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1, Menai, NSW 2234, Australia
R.A. Day
Affiliation:
Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1, Menai, NSW 2234, Australia
B.B. Ebbinghaus
Affiliation:
Lawrence Livermore National Laboratory, Livermore CA 94550, U.S.A.
Get access

Abstract

Baseline formulation titanate ceramics for surplus Pu disposition are based upon a target mineralogy of 95 wt.% pyrochlore (Ca0.89Gd0.22Hf0.23Pu0.22U0.44Ti2O7) plus 5 wt.% Hf-doped rutile (∼ Ti0.9Hf0.1O2), where Ce is used as an analogue for Pu and U, and Th for Pu. Typically, Pu/U, Th/U and Ce/U-baseline samples form major pyrochlore, plus minor brannerite (AnTi2O6) and rutile. Ce/Ce-baseline ceramics were similar but did not form brannerite. Sintering in air produced more U5+ in the ceramics than sintering in Ar. In the pyrochlore the charge compensation for U5+ principally occurred by an increase in Ca2+ and decrease in Ti4+ and Th4+. In the matrix these phase compositional changes result in an increase in brannerite content of the ceramic at the expense of pyrochlore in the air sintered ceramic relative to the Ar sintered sample. Sintering in reducing 3.7% H2 in Ar atmospheres eliminates the brannerite and rutile and results in 2M-zirconolite and perovskite in addition to the major pyrochlore phase. Varying the sintering temperature between 1250°C and 1400°C had little effect on the phase chemistry other than slightly incomplete reactivity of coarse actinide oxide at the lower sintering temperatures and a general increase in density (to ∼ 1350°C) and grain size with increased sintering temperatures. Th4+ appears to be a good analogue for Pu4+ from a crystal chemistry aspect.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 713: Symposium JJ – Scientific Basis for Nuclear Waste Management XXV , 2002 , JJ11.22
Copyright
Copyright © Materials Research Society 2002

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

1. Vance, E.R., Jostsons, A., Moricca, S., Stewart, M.W.A., Day, R.A., Begg, B.D., Hambley, M.J., Hart, K.P., and Ebbinghaus, B.B., in Ceramic Transactions Vol. 93, edited by Marra, J.C., and Chandler, G.T., (Am. Ceram. Soc., Westerville, OH, 1999) pp. 323–329.Google Scholar
2. Ringwood, A.E., Kesson, S.E., Reeve, K.D., Levins, D.M., and Ramm, E.J., in Radioactive Waste forms for the Future. edited by Lutze, W. and Ewing, R.C., (North-Holland, New York, 1988) pp. 233–324.Google Scholar
3. Ebbinghaus, B.B., Cicero-Herman, C., Gray, L., and Shaw, H., Plutonium Immobilization Project Baseline formulation, (Lawrence Livermore National Laboratory report UCRL-ID-133089, Feb. 1999) pp. 1–42.Google Scholar
4. Hill, R. J., Howard, C. J. and Hunter, B. A., A Computer Program for Rietveld Analysis of Fixed Wavelength X-ray and Neutron Powder Diffraction Patterns, (AAEC Report No. AAEC/M112, July 1986, Revised Jan. 1995, ANSTO, Lucas Heights, Australia).Google Scholar
5. Hovestreydt, E. R., J. Appl. Cryst., 16, 651–653 (1983).Google Scholar
6. Vance, E.R., Watson, J.N., Carter, M.L., Day, R.A., and Begg, B.D., J. Am. Ceram. Soc. 84 [1] 141–144 (2001).Google Scholar
7. Vance, E.R., Watson, J.N., Carter, M.L., Day, R.A., Lumpkin, G.R., Hart, K.P., Zhang, Y., McGlinn, P.J., Stewart, M.W.A., and Cassidy, D.J., Ceramic Transactions Vol. 107, edited by Chandler, G.T. and Feng, X. (Am. Ceram. Soc., Westerville, OH, 2000) pp. 561–568.Google Scholar
8. Zhang, Y., Hart, K.P., Blackford, M.G., Thomas, B.S., Aly, Z., Lumpkin, G.R., Stewart, M.W.A., McGlinn, P.J., and Brownscombe, A., in Scientific Basis for Nuclear Waste Management XXIV, (MRS Symp. Proc., Sydney 2000), in press.Google Scholar
9. Begg, B.D., Vance, E.R., Hunter, B.A., and Hanna, J.V., J. Mater. Res. 13, 3181–3190 (1998).Google Scholar
10. Ryerson, F.J., and Ebbinghaus, B., Pyrochlore-rich titanate ceramics for the immobilization of plutonium: Redox effects on phase equilibria on cerium- and thorium substituted analogs, (Lawrence Livermore National Laboratory report UCRL-ID-139092, May. 2000) pp. 6–41.Google Scholar
11. Stewart, M.W.A., Vance, E.R., Day, R.A., Leung, S.. Brownscombe, A., Carter, M.L., and Ebbinghaus, B.B., Ceramic Transactions Vol. 107, edited by Chandler, G.T. and Feng, X. (Am. Ceram. Soc., Westerville, OH, 2000) pp. 569–576.Google Scholar
12. Begg, B.D., Vance, E. R. and Conradson, S.D., J. Alloys and Comp. 271–273, 221–226 (1998).Google Scholar