Activation energy for diffusion of helium in water-saturated, compacted Na-montmorillonite

✍ Scribed by Tomohiro Higashihara; Hiraku Shibuya; Seichi Sato; Tamotsu Kozaki

• Publisher: Elsevier Science
• Year: 2005
• Tongue: English
• Weight: 122 KB
• Volume: 81
• Category: Article
• ISSN: 0013-7952
• DOI: 10.1016/j.enggeo.2005.06.017

✦ Synopsis

It is important to clarify the migration behavior of hydrogen gas dissolved in water-saturated, compacted bentonite, which is a promising material for geologic disposal of high-level waste and TRU waste disposal. The diffusion coefficients of helium, which can be detected under extremely low background conditions, in water-saturated, compacted Na-montmorillonite were determined as a function of temperature by a transient diffusion method. The activation energies for diffusion of helium were then obtained. The activation energies were from 6.9 F 4.8 to 19 F 2.8 kJ mol À 1 and were regarded to be independent of dry density. The activation energies of helium in water-saturated Na-montmorillonite were roughly equal to those in bulk water, 14.9 kJ mol À 1 , and in ice, from 11 to 13 kJ mol À 1 . It is possible that helium diffuses not only in pore water but also in interlayer water.