Insights into the thermo-hydraulic properties of compacted MX80 bentonite during hydration under elevated temperature

In high-level radioactive waste geological repositories, compacted bentonite undergoes coupled thermo-hydraulic processes due to heat released from a central waste canister and groundwater imbibition from the surrounding host rock. An understanding of these processes is essential for long-term simul...

Full description

Saved in:
Bibliographic Details
Published in:Canadian geotechnical journal 2024-02, Vol.61 (2), p.344-360
Main Authors: Lu, Yu, McCartney, John S.
Format: Article
Language:English
Subjects:
Bentonite
Corrosion
Corrosion effects
Groundwater
Heat conductivity
Heat transfer
High level radioactive wastes
High temperature
Hydration
Hydraulic conductivity
Hydraulic properties
Hydraulics
Imbibition
Moisture content
Radioactive wastes
Radioisotopes
Repositories
Shape
Shape effects
Soil compaction
Soil temperature
Soil water
Temperature dependence
Temperature effects
Temperature gradients
Temperature requirements
Thermal conductivity
Thermal simulation
Wetting
Wetting front
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:In high-level radioactive waste geological repositories, compacted bentonite undergoes coupled thermo-hydraulic processes due to heat released from a central waste canister and groundwater imbibition from the surrounding host rock. An understanding of these processes is essential for long-term simulations of radionuclide migration and canister corrosion, which requires an understanding of temperature effects on the coupled thermo-hydraulic properties governing these processes. In this study, a tank-scale radial infiltration test was used to investigate water imbibition processes in compacted bentonite under a central heater temperature of 200 °C that simulates high thermal gradients in a repository. Interpretation of this test focuses on evaluation of the liquid water wetting front during hydration and the interpretation of the temperature-dependent transient soil water retention curve (SWRC), thermal conductivity function (TCF), and hydraulic conductivity function (HCF). The SWRC during imbibition follows a temperature-dependent wetting path. Temperature effects on the hydraulic conductivity of bentonite in saturated conditions had the greatest effect on the shape of the HCF, with minimal temperature effects at higher suctions. The transient thermal conductivity data matched well with a new TCF linked with the SWRC shape. Although the bentonite layer was restrained, local deformations during hydration may have affected the shapes of the TCF and HCF.
ISSN:0008-3674
1208-6010
DOI:10.1139/cgj-2022-0537