Characterization of 222Rn entry into a basement structure surrounded by low-permeability soil.
An experimental facility has been developed to monitor the entry rate and concentration of 222Rn in a basement-type structure surrounded by soil having a permeability on the order of 10(-11) m2. A data acquisition system recorded environmental conditions outside and inside the structures, plus basement air exchange rate information, every 15 min. Indoor 222Rn concentrations ranged from 400 to 1,400 Bq m-3. The observed 222Rn entry rate is highly variable and has two primary components; a constant input rate caused by diffusion of 222Rn through the concrete walls and floor, and a variable rate that depends upon indoor-soil pressure differentials of only a few pascals. Pressure differentials are dependent upon wind speed and wind direction. Stack effect was not significant. During a 2-wk period, with relatively calm winds, diffusion through the concrete walls and floor plus the floor-wall joint accounted for more than 80% of the total 222Rn entry.
Department of Radiological Health Sciences, Colorado State University, Ft. Collins 80523.
D C
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Ward
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Borak
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Gadd
D000396:Air Pollutants, Radioactive; D016902:Air Pollution, Indoor; D006798:Housing; D010539:Permeability; D011886:Radon; D012987:Soil
D000396:Air Pollutants, Radioactive; D012987:Soil; D011886:Radon