Hostname: page-component-6bf8c574d5-gr6zb Total loading time: 0 Render date: 2025-02-15T09:32:24.980Z Has data issue: false hasContentIssue false
  • English
  • Français

A Study on Gas Migration Behavior in Buffer Material using X-ray CT Method

Published online by Cambridge University Press:  21 March 2011

K. Tanai  and
M. Yui
K. Tanai
Affiliation:
Waste Isolation Research Division, Waste Management and Fuel Cycle Research Center, Japan Nuclear Cycle Development Institute, Ibaraki, Japan
M. Yui
Affiliation:
Waste Isolation Research Division, Waste Management and Fuel Cycle Research Center, Japan Nuclear Cycle Development Institute, Ibaraki, Japan
Get access

Abstract

This paper presents a study on gas migration behavior in a bentonite specimen with the aid of X-ray computer tomography (CT) scan data. The laboratory experiment was carried out to clarify gas migration behavior through saturated, compacted bentonite. X-ray CT was used to estimate the spatial distribution of gas and water saturation during gas migration test in the bentonite. For the gas migration test, the controlled flow rate of gas injection was adopted for pre-compacted samples of Kunigel V1 bentonite using helium gas, which is safer than hydrogen gas.A specimen was isotropically consolidated and saturated by synthetic seawater, simultaneously, by applying a backpressure. This was followed by injecting the gas using a syringe pump. Inlet and outlet gas fluxes were monitored. This test exhibited a significant threshold pressure for breakthrough, somewhat larger than the sum of the swelling pressure and the backpressure.

The procedure of the X-ray CT measurement is as follows; i) measurement of the initial condition (saturated condition) of the compacted bentonite, ii) measurement of the gas injection condition as a function of time. The digital data obtained from the X-ray CT usually includes some noise. The stacking method can reduce the noise in CT values and enables to identify the gas migration area. The results indicate that gas is transported through preferential pathways in compacted bentonite, and is not homogenous.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 932: Symposium – Scientific Basis for Nuclear Waste Management XXIX , 2006 , 114.1
Copyright
Copyright © Materials Research Society 2006

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

[1] Otani, J., Mukunoki, T. and Sugawara, K., “Evaluation of particle crushing in soils using X-ray CT data”, Soils and Foundations vol 45, No.1, pp. 99–108 (2005).Google Scholar
[2] Tanai, K. and Yamamoto, M., “Experimental and modeling studies on gas migration in Kunigel V1 bentonite”, Research document, JNC TN8400 2003-024 (2003).Google Scholar
[3] Volckaert, G., Ortiz, L., De Cannière, P., Put, M., Horseman, S.T., Harrington, J.F., Fioravante, V. and Impey, M. “MEGAS -Modelling and experiments on gas migration in repository host rocks-”, 447pp, European Commission, Nuclear Science and Technology Series, Contract N° F12W-CT91-0076, Work carried out under a cost-shearing contract with the European Atomic Energy Community in the framework of its fourth R&D programme on ‘Management and storage of radioactive waste’ (1990-94), Part A, Task 4 ‘Disposal of radioactive waste’, Pegasus project, Directorate-General Science, Research and Development, Final report - Phase 1, EUR 16235 EN, Luxembourg, ISBN 92-827-4974-6 (1995).Google Scholar
[4] Ortiz, L., Volckaert, G., De Cannière, P., Put, M., Sen, M.A., Horseman, S.T., Harrington, J.F., Impey, M and Einchomb, S. “MEGAS –Modelling and experiments on gas migration in repository host rocks, 155pp., European Commision, Nuclear Science and Technology Series, Contract N° F12W-CT91-0076, Work carried out under a cost-shearing contract with the European Atomic Energy Community in the framework of its fourth R&D programme on ‘Management and storage of radioactive waste’, (1990-94), Part A, Task 4 ‘disposal of radioactive waste’, Directorate-General Science, Research and Development, Final report –Phase 2, EUR 17453 EN, Luxembourg, ISBN 92-827-9047-9 (1997).Google Scholar
[5] Sato, A., Fukahori, D. and Sugawara, K., “Crack opening analysis by the X-ray CT image subtraction method”, International Workshop on X-ray CT for Geomaterials, GEOX 2003, pp. 223–228 (2003).Google Scholar