ISSN: 0149-6115
Page Count: 9

Coupled Heat and Moisture Flow in Unsaturated Swelling Clay Barriers

Mohamed, AMO
Associate director, Geotechnical Research Centre, faculty lecturer,Civil Engineering and Applied Mechanics, McGill University,

Yong, RN
Professor,McGill University,Quebec,

Onofrei, CI
Engineering analyst,Fuel Waste Technology, Atomic Energy of Canada Limited Research, Whiteshell Laboratories,Manitoba,

Kjartanson, BH
Assistant professor,Iowa State University,IA,

Abstract

The main thermodynamic forces active in the near field of a nuclear fuel waste multiple barrier system during the unsaturated stage are the gradients of temperature, fluid pressure, and chemical potentials. The processes that have a direct impact on the transport mechanism of heat and moisture within the clay-based compacted buffer material are coupled. The major problems in describing coupled heat and moisture flow (CHMF) in unsaturated swelling clay barriers are the lack of experimental data and the lack of a method to estimate CHMF diffusivity parameters (CHMF-DIPAR).

This paper presents the experimental procedures, the analysis of experimental data, and a method of determining CHMF-DIPAR. Several series of one-dimensional tests were performed to examine the transient temperature and moisture flow in buffer material compacted at a dry density of 1.67 Mg/m³ and optimum volumetric moisture content (VMC) of 0.28. CHMF-DIPAR were calculated using the measured temperature and moisture distributions combined with an analytical solution of CHMF equation and a square-root time (SQRT) technique.

Keywords:
unsaturated, swelling, temperature, moisture, analytical, diffusivity, graphical

Paper ID: GTJ10338J
DOI: 10.1520/GTJ10338J
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