Modeling radon entry into Florida slab-on-grade houses

Journal Article · Fri Oct 01 04:00:00 EDT 1993 · Health Physics; (United States)

DOI:https://doi.org/10.1097/00004032-199310000-00004· OSTI ID:5959341

Revzan, K L; Fisk, W J; Sextro, R G ^[1]

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1. Lawrence Berkeley Laboratory, Berkeley, CA (United States)

Radon entry into a Florida house whose concrete slab is supported by a permeable concrete-block stem wall and a concrete footer is modeled. The slab rests on backfill material; the same material is used to fill the footer trench. A region of undisturbed soil is assumed to extend 10 m beyond and below the footer. The soil is assumed homogeneous and isotropic except for certain simulations in which soil layers of high permeability or radium content are introduced. Depressurization of the house induces a pressure field in the soil and backfill. The Laplace equation, resulting from Darcy's law and the continuity equation, is solved using a steady-state finite-difference model to determine this field. The mass-transport equation is then solved to obtain the diffusive and advective radon entry rates through the slab; the permeable stem wall; gaps at the intersections of the slab, stem wall, and footer; and gaps in the slab. These rates are determined for variable soil, backfill, and stem-wall permeability and radium content, slab-opening width and position, slab and stem-wall diffusivity, and water table depth. The variations in soil permeability and radium content include cases of horizontally stratified soil. We also consider the effect of a gap between the edge of the slab and the stem wall that restricts the passage of soil gas from the stem wall into the house. Calculations indicate that the total radon entry rate is relatively low unless the soil or backfill permeability or radium content is high. Variations in most of the factors, other than the soil permeability and radium content, have only a small effect on the total radon entry rate. However, for a fixed soil permeability, the total radon entry rate may be reduced by a factor of 2 or more by decreasing the backfill permeability, by making the stem wall impermeable and gap-free, (possibly by constructing a one-piece slab/stem-wall/footer), or by increasing the pressure in the interior of the stem wall.

• OSTI ID: 5959341
• Journal Information: Health Physics; (United States), Journal Name: Health Physics; (United States) Vol. 65:4; ISSN HLTPAO; ISSN 0017-9078
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540230* -- Environment
Terrestrial-- Radioactive Materials Monitoring & Transport-- (1990-)
AIR POLLUTION
ARCHITECTURE
BUILDINGS
DEVELOPED COUNTRIES
DIFFERENTIAL EQUATIONS
ECOLOGICAL CONCENTRATION
ELEMENTS
EQUATIONS
FLORIDA
FLUIDS
FOUNDATIONS
FUNCTIONAL MODELS
GASES
HOUSES
INDOOR AIR POLLUTION
LAPLACE EQUATION
MECHANICAL STRUCTURES
NONMETALS
NORTH AMERICA
PARTIAL DIFFERENTIAL EQUATIONS
PERMEABILITY
POLLUTION
RADON
RARE GASES
RESIDENTIAL BUILDINGS
SOIL-STRUCTURE INTERACTIONS
SOILS
SUPPORTS
USA