Hostname: page-component-77c89778f8-5wvtr Total loading time: 0 Render date: 2024-07-16T17:34:56.561Z Has data issue: false hasContentIssue false
  • English
  • Français

Phases Formation Rate at Synthesis of Actinide Waste Forms

Published online by Cambridge University Press:  11 February 2011

N. P. Laverov ,
S. V. Yudintsev ,
M. I. Lapina ,
S. V. Stefanovsky ,
S. C. Chae  and
R. C. Ewing
N. P. Laverov
Affiliation:
IGEM RAS, Staromonetny 35, Moscow 119017, RUSSIA
S. V. Yudintsev
Affiliation:
IGEM RAS, Staromonetny 35, Moscow 119017, RUSSIA
M. I. Lapina
Affiliation:
IGEM RAS, Staromonetny 35, Moscow 119017, RUSSIA
S. V. Stefanovsky
Affiliation:
SIA Radon, 7th Rostovskii per., 2/14, Moscow 119121, RUSSIA
S. C. Chae
Affiliation:
KIGAM, 30 Kajung-Dong, Yusung-Ku, Taejon, KOREA
R. C. Ewing
Affiliation:
University of Michigan, Ann Arbor, MI, 48109–2104, USA.
Get access

Abstract

Rate of zirconolite (CaZrTi2O7) and pyrochlores (Gd2Ti2O7, CaCeTi2O7, and Gd2Zr2O7) formation by cold pressing and sintering (CPS) was studied. Batches were prepared from CaCO3, ZrO2, TiO2, CeO2, and Gd2O3 milled to size of 20–30 micrometers. Powders were compacted and sintered in air (oxygen) at 800–1600 °C for 0.5–55 hours. Samples were examined with XRD, SEM, and TEM. Phase formation rate was the fastest in Gd-Ti-O and Ca-Ce-Ti-O systems and the reactions were the slowest in Gd-Zr-O system. In zirconolite-based system reaction rate had intermediate value. For three systems at 1400 C equilibrium was reached in 3–5 hours, while in Gd-Zr-O system required about ten time longer reaction time. High formation rate was evidently one of the reasons to select the pyrochlore (Ca,Gd,U,Pu)2(Hf,Ti)2 O7 as a host for Pu in the USA.

We have also studied an effect of titanium on pyrochlore formation in the Gd-Zr-Ti-O system. The batches with nominal composition Gd2Ti0.4Zr1.6O7, Gd2Ti0.2Zr1.8O7, and Gd2Ti0.1Zr1.9O7 were compacted and annealed at 1500–1600 °C for 3–98 hours. In most of them along with pyrochlore non-reacted zirconium and gadolinium oxides were found. Their content reduced with temperature and sintering duration increasing. Pyrochlore composition was varied in different parts of the samples. Variation range decreased with rise of temperature, runs duration, and titanium content in the precursors. Partial substitution of Ti for Zr increased rate of pyrochlore formation. However, even at the highest titanium content (0.4 formula units) and temperature of synthesis (1600 °C) too long sintering duration in tens of hours is required to form a single-phase pyrochlore matrix. This makes their production from oxide precursor via CPS route inefficient. Inductive melting in a cold crucible or self-sustaining high-temperature synthesis are more promising methods for fabrication of the zirconate pyrochlores.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 757: Symposium II – Scientific Basis for Nuclear Waste Management XXVI , 2002 , II3.20
Copyright
Copyright © Materials Research Society 2003

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. Ringwood, A.E., Kesson, S.E., Reeve, K.D. et al, in Radioactive Waste Forms for the Future, edited by Lutze, W. and Ewing, R.C. (Elsevier Science Publishers, New York, 1988), p. 233.Google Scholar
2. Vance, E.R., Ball, C.J., and Day, R.A., J. Alloys Comp. 213/214, 406 (1994).Google Scholar
3. Vance, E.R., Begg, B.D., Day, R.A., and Ball, C.J., in Scientific Basis for Nuclear Waste Management XVIII, edited by Murakami, T. and Ewing, R.C. (Mat. Res. Soc. Proc. 353, Pittsburgh, PA, 1995) 767–774.Google Scholar
4. Ewing, R.C., Proc. Natl. Acad. Sci. USA 96, 3432 (1999).Google Scholar
5. Wang, S.X., Begg, B.D. and Wang, L.M., J. Mat. Res. 14, 4470 (1999).Google Scholar
6. Raison, P.E., Haire, R.G., Sato, T., and Ogawa, T., in Scientific Basis for Nuclear Waste Management XXII, edited by Wronkiewicz, D.J. and Lee, J.H. (Mat. Res. Soc. Proc. 556, Pittsburgh, PA, 1999) 3–10.Google Scholar
7. Laverov, N.P., Yudintsev, S.V., Stefanovsky, S.V. et al., Doklady RAS (Rus.) 381 399 (2001).Google Scholar
8. Ebbinghaus, B.B., VanKonynenburg, R.A., et al., Waste Management '98, Tucson, AZ, 65–04 (1998).Google Scholar
9. Brummond, W. and Armantrout, G., Waste Management '98, Tucson, AZ, 65–05 (1998).Google Scholar
10. Vance, E.R., Cassidy, D.J., Ball, C.J., and Thorogood, G.J., J. Nucl. Mater. 190 295 (1992).Google Scholar
11. Stefanovsky, S.V., Yudintsev, S.V., Nikonov, B.S., Omel'yanenko, B.I., Geoecology (Rus.) 4 58 (1996).Google Scholar
12. Swenson, D., Nieh, T.G., and Fournelle, J.H., in Scientific Basis for Nuclear Waste Management XIX, edited by Murphy, W.M. and Knecht, D.A. (Mat. Res. Soc. Proc. 412, Pittsburgh, PA, 1996) pp. 337–344.Google Scholar
13. Xu, H., Wang, Y., Putnam, R.L. et al., in Scientific Basis for Nuclear Waste Management XXIII, edited by Smith, R.W. and Shoesmith, D.W. (Mat. Res. Soc. Proc. 608, Warrendale, PA, 2000) pp. 461–466.Google Scholar
14. Begg, B.D., Vance, E.R., Lumpkin, G.R., in Scientific Basis for Nuclear Waste Management XXI, edited by Murakami, T. and Ewing, R.C. (Mat. Res. Soc. Proc. 506, Pittsburgh, PA, 1998) pp. 79–86.Google Scholar
15. Fortner, J.A., Kropf, A.J., Bakel, A.J. et al., in Scientific Basis for Nuclear Waste Management XXIII, edited by Smith, R.W. and Shoesmith, D.W. (Mat. Res. Soc. Proc. 608, Warrendale, PA, 2000) pp. 401–406.Google Scholar
16. Knyazev, O.A., Stefanovsky, S.V., Yudintsev, S.V., in Scientific Basis for Nuclear Waste Management XX, edited by Gray, W.J. and Triay, I.R. (Mat. Res. Soc. Proc. 465, Pittsburgh, PA, 1997) pp. 401–408.Google Scholar
17. Glagovsky, E.M., Yudintsev, S.V., Kuprin, A.V. et al., Radiochemistry 43, 632 (2001).Google Scholar
18. Stefanovsky, S.V. and Chizhevskaya, S.V., Waste Management '00, Tucson, AZ, Rep. 55–4 (2000).Google Scholar