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Diffusivity and Porosity in Rock Matrix—Laboratory Methods Using Artificial and Natural Tracers

Published online by Cambridge University Press:  01 January 1992

M. Valkiainen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, P.O. Box 200, SF-02151 Espoo, Finland
M. Olin
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, P.O. Box 200, SF-02151 Espoo, Finland
K. Uusheimo
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, P.O. Box 200, SF-02151 Espoo, Finland
H. Kumpulainen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, P.O. Box 200, SF-02151 Espoo, Finland
J. Lehikoinen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, P.O. Box 200, SF-02151 Espoo, Finland
A. Muurinen
Affiliation:
Technical Research Centre of Finland, Reactor Laboratory, P.O. Box 200, SF-02151 Espoo, Finland
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Abstract

The nature of diffusivity and porosity in crystalline rock was studied by electrical conductivity measurements, steady-state diffusion experiments, saturation-leaching of tracers with cylindrical rock samples and analysis of the concentrations of different elements from core samples or pore water near fractures. The phenomena of main interest were dead-end porosity, ion-exclusion, sorption, and the continuity of pore networks. The modelling of experimental results was based on a modified Fick's second law for diffusion, which was solved either by analytical or numerical methods. The measured De and ε were found to statistically follow an exponential presentation: Archie's law. The existence of ion-exclusion for anions was confirmed. The connectivity of the pore network extended in the laboratory experiments at least six centimetres, in coarse-grained granite in nature several metres but in fine-grained rock samples of a uranium deposit the element mobilization effects could be seen only to the depth of 2–3 centimetres.

Type
Research Article
Copyright
Copyright © Materials Research Society 1993

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References

REFERENCES

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