A theoretical convective-transport model of indoor radon decay products

Technical Report · Sat Apr 01 04:00:00 EST 1989

DOI:https://doi.org/10.2172/5905861· OSTI ID:5905861

Schiller, G. E.

A numerical model is developed which is capable of simulating the generation, convective and diffusive transport, and removal mechanisms of radon and radon decay products (daughters). The model is based on fundamental mass-transport equations. Specifically, separate differential equations describe the spatially-dependent concentrations of both unattached (free) daughters and daughters attached to airborne aerosols; the equations are coupled through source and sink terms which include the radioactive decay rate, attachment rate, and recoil factor. Surface deposition of airborne daughters by molecular diffusion is accounted for through boundary conditions. The mass-transport model is employed to examine the influence of key parameters on free and attached deposition rates of the first three radon daughters, with a particular emphasis on the first free daughter, /sup 218/Po. These parameters -- free daughter diffusivity, aerosol particle concentration, and convective air motion -- provide a partial description of the physical and environmental conditions which are likely to have the greatest influence on deposition rates. The effects of air motion on the transport and deposition of radon daughters are examined for laminar, buoyancy-driven enclosure flows and for both free and forced convection boundary layer flows.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 5905861
• Report Number(s): LBL-20096; ON: DE89014892
• Country of Publication: United States
• Language: English

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