Skip to main content Accessibility help
×
Home

Dissolution Mechanisms of CaTiO3 - Solution Analysis, Surface Analysis and Electron Microscope Studies Implications for Synroc

  • D. K. Pham (a1), F. B. Neall (a1), S. Myhra (a1), R.ST.C Smart (a1) and P. S. Turner (a1)...

Abstract

The perovskite CaTiO3 is one of the major phases of the Synroc titanate mineral assemblage. Its chemical durability in an aqueous environment, which is relevant to the Synroc concept, has been investigated by solution analysis, surface analysis and electron microscopy. In general it has been found that dissolution due to base catalyzed hydrolysis is the most significant mechanism of attack; the results suggest that an ion exchange mechanism is confined to the first monolayer. Below 90°C the extent of attack, and release of Ca into solution, is limited by the formation of a titanaceous amorphous layer (” 100A thickness) which imposes a reaction constraint at the film-solid interface. Dissolution may also be constrained by the pH and Ca2 +concentration in the bulk liquid. Above 90°C dissolution is relatively less constrained due to instability of the amorphous layer which is replaced by nucleation and epitaxial growth of TiO2 on the dissolving substrate. Thermodynamic stability of CaTiO3 for T< 90°C can easily be engineered into the waste repository, while hydrothermal stability (T > 90°C) is more difficult to achieve.

Copyright

References

Hide All
1. Ringwood, A.E., Safe Disposai of High Level Nuclear Reactor Waste: A New Strategy. ANU Press, Canberra (1978).
2. Fielding, P.E. and White, T.J., J. Mater. Res., 2, 387 (1987).
3. Oversby, V.M. and Ringwood, A.E., Radioactive Waste Manage., 2, 223 (1982).
4. Levins, D.M., Reeve, K.D., Buykx, W.J., Ryan, R.K., Seatonberry, B.W. and Woolfrey, J.L., Spectrum '86. ANS Int. Topical Meeting on Waste Management, Decontamination and Decommissioning, Sept. 14 18, 1986 Niagara Falls, USA.
5. Nuclear Waste Materials Handbook - Test Methods. Materials Characterization Center, Pacific Northwest Laboratory. UOE/TIC-11400, Rev 1 (1983).
6. Myhra, S., Smart, R. St. C. and Turner, P.S., Scanning Microscopy, 2, 715 (1988).
7. Myhra, S., Smart, R. St. C. Turner, P.S. and Neall, F.B., Final Report NERDDC Project No. 673, Aust. Govt. Publishing Office (1986).
8. Myhra, S., Atkinson, A., Riviere, J.C. and Savage, D., J. Am. Ceram. Soc., 67, 223 (1984).
9. Smart, R. St. C. Smart, Appl. Surface Sci., 22/23, 90 (1985).
10. Myhra, S., Savage, D., Atkinson, A. and Riviere, J.C., Am. Mineral., 69, 902 (1984).
11. Kastrissios, T., Stephenson, M., Turner, P.S. and White, T.J., J. Am. Ceram. Soc, 70, C144 (1987).
12. Myhra, S., Bishop, H.E., Riviere, J.C. and Stephenson, M., J. Mat. Sci., 22, 3217 (1987).
13. Nesbitt, H.W., Bancroft, G.M., Fyfe, W.S., Karkhanis, S.N., Nishijima, A. and Shin, S., Nature, 289, 358 (1981).
14. Robie, R.A., Hemingway, B.S. and Fisher, J.R., Bull. U.S. Geol. Surv., No. 1452, (1978).
15. Baes, C.F. and Mesmer, R.E., The Hydrolysis of Cations, Wiley-Interscience, New York (1976).
16. Wolery, T.J., Calculation of Chemical Equilibrium Between Aqueous Solution and Minerals: The EQ3/6 Software Package, Lawrence Livermore Laboratory, UCRL-52658 (1979).

Dissolution Mechanisms of CaTiO3 - Solution Analysis, Surface Analysis and Electron Microscope Studies Implications for Synroc

  • D. K. Pham (a1), F. B. Neall (a1), S. Myhra (a1), R.ST.C Smart (a1) and P. S. Turner (a1)...

Metrics

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed