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Claystone Constraints on Models of the Long-Term Chemical Evolution of Buffer Porewaters

Published online by Cambridge University Press:  10 February 2011

R. C. Arthur  and
J. Wang
R. C. Arthur
Affiliation:
Monitor Scientific, LLC, Denver, CO 80235, [email protected]
J. Wang
Affiliation:
Beijing Research Institute of Geology, Beijing, PR CHINA, [email protected]
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Abstract

Geochemical models of clay-water interaction are evaluated using data characterizing the hydrochemical, isotopic and mineralogical properties of a natural claystone that is similar to bentonite buffers that have evolved over long periods of time in a deep geologic repository for nuclear wastes. Model predictions in general compare favorably with the mineralogy and hydrochemistry of this formation if increases in pH due to partial CO2(g) exsolution from porewater samples is accounted for. This suggests the models can be used with enhanced confidence to accurately predict the chemistry of pore fluids in bentonite buffers, enabling more defensible estimates to be made of radioelement solubilities that partially define the source term in performance assessments. Modifications are needed, however, to improve the accuracy of thermodynamic data supporting the models and to account for potential effects on porewater compositions of reactions that are kinetically inhibited from attaining equilibrium over experimental time scales.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 608: Symposium QQ – Scientific Basis for Nuclear Waste Management XXIII , 1999 , 551
Copyright
Copyright © Materials Research Society 2000

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References

REFERENCES

1 McKinley, I. G. and Savage, D., in Fourth International Conference on the Chemistry and Migration Behavior of Actinides and Fission Products in the Geosphere (R. Oldenbourg Verlag, München, 1994), p. 657–665.Google Scholar
2 Bath, A.H., Ross, C.A.M., Entwisle, D., Cave, M.R., Green, K.A., Reeder, S. and Fry, M., Hydrochemistry of Porewaters from London Clay, Lower London Tertiaries and Chalk at the Bradwell Site, Rep. Brit. Geol. Surv. WE/89/26, Keyworth, U.K. (1989).Google Scholar
3 Pearson, F.J., Lolcama, J.L. and Scholtis, A., Chemistry of Waters in the Boettstein, Weiach, Riniken, Schafishheim, Kaisten and Leuggern Boreholes: A Hydrochemically Consistent Data Set, Nagra TR 86-19, Nagra, Wettingen, Switzerland (1989).Google Scholar
4 Stumm, W. and Morgan, J.J., Aquatic Chemistry, 3rd ed., Wiley Interscience, New York, 1996, pp.393–394.Google Scholar
5 Bethke, C. M., Geochemical Reaction Modeling, Oxford Univ. Press, New York, 1996, 397p.Google Scholar
6 data0.3245r46, compiled by the Geochemical Modeling Group, Lawrence Livermore National Laboratory, Livermore, CA, and accessible by ftp to s122.es.llnl.gov.Google Scholar
7 Garrels, R.M., Clays Clay Miner., 32(6), p.161–166 (1984).Google Scholar
8 Wanner, H., Wersin, P. and Sierro, N., Thermodynamic Modeling of Bentonite-Groundwater Interaction and Implications for Near-Field Chemistry in a Repository for Spent Fuel, SKB TR 92-37, Swedish Nuclear Fuel and Waste Management Co., Stockholm, Sweden (1992).Google Scholar
9 Aagaard, P. and Helgeson, H.C., Clays Clay Miner., 31(3), p.207–217 (1983)Google Scholar
10 Giggenbach, W.F., Chem. Geol., 49, p. 231–242 (1985)Google Scholar