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Title: Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor

Abstract

Packed columns of canister packing material containing 25% bentonite and 75% quartz or basalt sand, were exposed to water vapor at temperatures up t 260/sup 0/C. The permeabilities of the columns were subsequently measured after complete saturation with liquid water in a pressurized system. Exposure to water vapor caused irreversible increases in permeability by factors of up to 10/sup 5/. After saturation with liquid water, the permeability was nearly independent of temperature. The increases in permeability were due to a large decrease in the ability of the bentonite to swell in water. Calculations suggest that swelling of bentonite altered at 250/sup 0/C was not sufficient to fill the pore spaces. If the pore spaces are filled, the mixture will form an effective barrier against flow, diffusion, and transport of colloids. The results suggest that if bentonite-based canister packing material is exposed even briefly to water vapor at high temperatures in a high-level nuclear waste repository, its performance will be seriously impaired. The problem is less severe if the proportion of bentonite is high and the material is highly compacted. Previous results show significant degradation of bentonite by water vapor at temperatures as low as 150/sup 0/C. This suggests that inmore » some repositories, backfill in tunnels and drifts may also be affected. 9 references, 5 figures, 1 table.« less

Authors:
Publication Date:
Research Org.:
Argonne National Lab., IL (USA)
OSTI Identifier:
6323040
Report Number(s):
CONF-841157-18
ON: DE85001841
DOE Contract Number:  
W-31-109-ENG-38
Resource Type:
Conference
Resource Relation:
Conference: Symposium on the scientific basis for nuclear waste management, Boston, MA, USA, 26 Nov 1984; Other Information: Paper copy only, copy does not permit microfiche production
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES; BENTONITE; PERMEABILITY; POROSITY; SAND; BACKFILLING; BASALT; EXPERIMENTAL DATA; HIGH TEMPERATURE; HIGH-LEVEL RADIOACTIVE WASTES; MIXTURES; PERFORMANCE; TEMPERATURE EFFECTS; WATER VAPOR; CLAYS; DATA; DISPERSIONS; FLUIDS; GASES; IGNEOUS ROCKS; INFORMATION; MATERIALS; NUMERICAL DATA; RADIOACTIVE MATERIALS; RADIOACTIVE WASTES; ROCKS; VAPORS; VOLCANIC ROCKS; WASTES; 360603* - Materials- Properties; 052002 - Nuclear Fuels- Waste Disposal & Storage

Citation Formats

Couture, R A. Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor. United States: N. p., 1984. Web.
Couture, R A. Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor. United States.
Couture, R A. Sun . "Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor". United States. https://www.osti.gov/servlets/purl/6323040.
@article{osti_6323040,
title = {Rapid increases in permeability and porosity of bentonite-sand mixtures due to alteration by water vapor},
author = {Couture, R A},
abstractNote = {Packed columns of canister packing material containing 25% bentonite and 75% quartz or basalt sand, were exposed to water vapor at temperatures up t 260/sup 0/C. The permeabilities of the columns were subsequently measured after complete saturation with liquid water in a pressurized system. Exposure to water vapor caused irreversible increases in permeability by factors of up to 10/sup 5/. After saturation with liquid water, the permeability was nearly independent of temperature. The increases in permeability were due to a large decrease in the ability of the bentonite to swell in water. Calculations suggest that swelling of bentonite altered at 250/sup 0/C was not sufficient to fill the pore spaces. If the pore spaces are filled, the mixture will form an effective barrier against flow, diffusion, and transport of colloids. The results suggest that if bentonite-based canister packing material is exposed even briefly to water vapor at high temperatures in a high-level nuclear waste repository, its performance will be seriously impaired. The problem is less severe if the proportion of bentonite is high and the material is highly compacted. Previous results show significant degradation of bentonite by water vapor at temperatures as low as 150/sup 0/C. This suggests that in some repositories, backfill in tunnels and drifts may also be affected. 9 references, 5 figures, 1 table.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1984},
month = {1}
}

Conference:
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