The Influence of a Subslab Gravel Layer and Open Area on Soil-Gas and Radon Entry into Two Experimental Basements
Measurements of steady-state soil-gas and {sup 222}Rn entry rates into two room-sized, experimental basement structures were made for a range of structure depressurizations (0-40 Pa) and open areas (0-165 x 10{sup -4} m{sup 2}). The structures are identical except that in one the floor slab lies directly on native soil whereas in the other the slab lies on a high permeability gravel layer. The subslab gravel layer greatly enhances the soil-gas and radon entry rate into the structure. The radon entry rate into the structure with the subslab gravel layer is four times greater than the entry rate into the structure without the gravel layer with an open area of 165 x 10{sup -4} m{sup 2}; the ratio increases to 30 for an open area of 5.0 x 10{sup -4} m{sup 2}. Although open area is a poor indicator of radon and soil-gas entry into the experimental structure, the extension of the soil-gas pressure field created by structure depressurization is a good measure of the radon entry rate into the experimental structures. The measured normalized radon entry rate into both structures has the same linear relationship with the average subslab pressure coupling regardless of open area. The average subslab pressure coupling is a measure of the extension of the soil-gas pressure field. A three-dimensional finite-difference model correctly predicts the effect of a subslab gravel layer, and different open area configurations on radon and soil-gas entry rate; however, the model underpredicts the absolute entry rates into both structures by a factor of 1.5.
- Research Organization:
- Ernest Orlando Lawrence Berkeley National Laboratory, Berkeley, CA (US)
- Sponsoring Organization:
- Environmental Energy Technologies Division
- DOE Contract Number:
- AC02-05CH11231
- OSTI ID:
- 1009820
- Report Number(s):
- LBL-35943
- Journal Information:
- Health Physics, Journal Name: Health Physics Journal Issue: 3 Vol. 69; ISSN HLTPAO; ISSN 0017-9078
- Country of Publication:
- United States
- Language:
- English
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