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Experimental Study of Gas Permeabilities and BreakthroughPressures in Clays

Published online by Cambridge University Press:  03 September 2012

K. Tanai ,
T. Kanno  and
C. Gallé
K. Tanai
Affiliation:
Geological Isolation Technology Section, PNC Tokai Works, Tokai-mura, Ibaraki, JAPAN.
T. Kanno
Affiliation:
Geological Isolation Technology Section, PNC Tokai Works, Tokai-mura, Ibaraki, JAPAN.
C. Gallé
Affiliation:
Département d'Entreposage et de Stockage des Déchets, CEA Saclay, 91191 Gif-sur-yvette, FRANCE.
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Abstract

In this study, gas migration experiments in unsaturated and saturated stateswere carried out to clarify the fundamental gas migration characteristics incompacted bentonite to be used for the geological disposal of high-levelradioactive waste. In unsaturated experiments, the gas permeability forJapanese bentonite (Kunigel VI) as a function of degree of saturation wasmeasured to examine the applicability of conventional two-phase flow modelsto compacted bentonite. The intrinsic permeability obtained in this studywas about five orders of magnitude larger than that obtained in waterpermeation tests with the same density. The difference seems to originatefrom the change of pore structure due to the swelling phenomenon of thebentonite. Since these effects have not been evaluated quantitatively yet,various relative gas permeability functions of conventional two-phase flowmodels were applied as a first approximation.

Saturated experiments designed to simulate the gas migration phenomenon in arepository for the waste were carried out to obtain relationship betweenbreakthrough and swelling pressures using Kunigel VI and French Fo-Ca clayin saturation state. The reproducibility of the breakthrough pressure wasalso examined for Kunigel VI bentonite. The breakthrough pressure was almostthe same as swelling pressure irrespective of the type of clay. As to thereproducibility of breakthrough pressure, it was observed that first andsecond breakthrough pressures were almost the same for Kunigel VI specimenswith the dry densities of 1.7 and 1.8 g/cm3.

Information

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 465: Symposium II – Scienfific Basis for Nuclear Waste Management XX , 1996 , 995
Copyright
Copyright © Materials Research Society 1997

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References

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