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Coupled Chemical and Diffusion Model for Compacted Bentonite

Published online by Cambridge University Press:  15 February 2011

M. Olin ,
J. Lehikoinen  and
A. Muurinen
M. Olin
Affiliation:
VTT Chemical Technology, P.O.Box 1404 (Otakaari 3A, Espoo), FIN-02044 VTT, Finland
J. Lehikoinen
Affiliation:
VTT Chemical Technology, P.O.Box 1404 (Otakaari 3A, Espoo), FIN-02044 VTT, Finland
A. Muurinen
Affiliation:
VTT Chemical Technology, P.O.Box 1404 (Otakaari 3A, Espoo), FIN-02044 VTT, Finland
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Abstract

A chemical equilibrium model has been developed for ion-exchange and to a limited extent for other reactions, such as precipitation or dissolution of calcite or gypsum, in compacted bentonite water systems. The model was successfully applied to some bentonite experiments, especially as far as monovalent ions were concerned. The fitted log-binding constants for the exchange of sodium for potassium, magnesium, and calcium were 0.27, 1.50, and 2.10, respectively. In addition, a coupled chemical and diffusion model has been developed to take account of diffusion in pore water, surface diffusion and ion-exchange. The model was applied to the same experiments as the chemical equilibrium model, and its validation was found pardy successful. The above values for binding constants were used also in the coupled model. The apparent (both for anions and cations) and surface diffusion (only for cations) constants yielding the best agreement between calculated and experimental data were 3.0×10-11 m2/s and 6.0×10-12m2/s, respectively. These values are questionable, however, as experimental results good enough for fitting are currently not available.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 353: Symposium – Scientific Basis for Nuclear Waste Management XVIII , 1994 , 253
Copyright
Copyright © Materials Research Society 1995

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References

REFERENCES

1. Wanner, H., in Scientific Basis for Nuclear Waste Management IX, edited by Werme, L.O. (Mater. Res. Soc. Proc. 50, Pittsburgh, 1985), pp. 509–516.Google Scholar
2. Muurinen, A., PhD thesis, VTT Publications 168, 1994.Google Scholar
3. Rasmuson, A. and Neretnieks, I., SKBF/KBS, Report 83–37, 1983.Google Scholar
4. Melamed, A., Pitkänen, P., Olin, M., Muurinen, A. and Snellman, M., in Scientific Basis for Nuclear Waste Management XV. edited by Sombret, C.G. (Mater. Res. Soc. Proc. 257, Pittsburgh, 1991), pp. 557–566.Google Scholar
5. Olin, M., PhD thesis, VTT Publications 175, 1994.Google Scholar
6. Lehikoinen, J., To Be Published In Vtt Publications (In Finnish).Google Scholar
7. Snellman, M., Uotila, H. and Rantanen, J., in Scientific Basis for Nuclear Waste Management XII, edited by Lutze, W. and Ewing, R.C. (Mater. Res. Soc. Proc. 127, Pittsburgh, 1987) , pp. 781–791. J.S. Jacobsen and C.L. Carnahan, ibid., pp. 749–754.Google Scholar
8. Allard, B., Larson, S.A., Albinsson, Y., Tyllborg, E.L., Karlsson, M., Andersson, K. and Torstenfeldt, B. B. 1981. in Near Field Phenomena in Geologic Repositories for Radioactive Waste (OECD/NEA, Paris, 1981), pp. 93–101.Google Scholar
9. 386-MATLAB user’s guide, for 80386-based MS-DOS personal computers. The Math-Works, Inc. Natick, Massachusetts.Google Scholar
10. Dennis, J.E. Jr. and Schnabel, R.B., Numerical methods for unconstrained optimization and nonlinear equations (Prentice-Hall International, New Jersey, 1983), p. 378.Google Scholar
11. Meintjes, K. and Morgan, A.P., Appl. Math. Comp., 22, 333 (1987).Google Scholar
12. Jacobsen, J.S. and Carnahan, C.L., in Scientific Basis for Nuclear Waste Management XI. edited by Apted, M.J. and Westerman, R.E., (Mater. Res. Soc. Proc. 112, Pittsburgh, 1988), pp. 415–424.Google Scholar