Thermodiffusion in concrete slab as a driving force of indoor radon entry.
The core of the hypotheses considered is that there is an additional strong driving force-the thermodiffusion of radon and soil air in concrete and soils, which can cause an intensive indoor radon entry. A vertical thermogradient in the slab causes thermodiffusion air flux through concrete into the house. The proof of this concept is based on consideration of concrete slab as a micro-porous system having a pore-size distribution that mostly pertains to Knudsen's region and a transition zone of pore sizes. The Knudsen's theory for a transition zone is developed, which is consistent with the known experimental data of thermodiffusion. Calculated thermodiffusion air flux across a concrete slab under thermogradient 80 K m(-1) approximately ranges 1 x 10(-7)-1 x 10(-6) kg x m(-2) x s(-1). The calculated typical radon-bearing advective air velocity in soil due to thermogradient in the slab is about 1 x 10(-6) m x s(-1).
Minkin
L
L
Portland Community College, Physics Department, OR 97219, USA. lminkin@pcc.edu
D000396:Air Pollutants, Radioactive; D016902:Air Pollution, Indoor; D003252:Construction Materials; D004058:Diffusion; D008962:Models, Theoretical; D011886:Radon; D013696:Temperature; D013816:Thermodynamics
D000396:Air Pollutants, Radioactive; D011886:Radon