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Methods for measuring diffusion coefficients of radon in building materials.
1Nuclear Geophysics Division, Kernfysisch Versneller Institut, University of Groningen, The Netherlands. cozmuta@kvi.nl
The Science of the Total Environment
|May 31, 2001
Summary
Determining the radon diffusion coefficient in concrete proved challenging. The second method, using hollow cylinders, successfully measured the radon bulk diffusion coefficient at (4.6 +/- 0.4) x 10(-6) cm2 s(-1).
Area of Science:
- Environmental Science
- Materials Science
- Nuclear Engineering
Background:
- Radon-222 (Rn-222) is a naturally occurring radioactive gas that can accumulate in buildings, posing a health risk.
- Accurate measurement of the radon diffusion coefficient in construction materials like concrete is crucial for developing effective mitigation strategies.
- Existing methods for determining radon diffusion in concrete have limitations in practical application and sealing effectiveness.
Purpose of the Study:
- To present and evaluate two distinct methods for determining the radon diffusion coefficient in concrete.
- To assess the practical challenges and effectiveness of radon-tight sealing techniques for concrete surfaces.
- To experimentally measure the radon bulk diffusion coefficient of a concrete sample.
Main Methods:
- Flush and adsorption techniques were used to measure radon release rates for both methods.
- Method 1: Theoretical analysis of a cubical concrete sample using radon diffusion equation with zero flux boundary conditions, comparing computed and measured release rates.
- Method 2: Experimental setup with hollow cylindrical concrete specimens, enforcing a one-dimensional diffusion situation with zero flux at the ends, using an internal radon source.
Main Results:
- Method 1: Investigated coverings were ineffective for radon-tight sealing, preventing clear determination of the diffusion coefficient.
- Method 2: Successful sealing was tested on an aluminum dummy, allowing for experimental measurement.
- The radon bulk diffusion coefficient for the concrete sample was determined as D = (4.6 +/- 0.4) x 10(-6) cm2 s(-1).
Conclusions:
- Radon-tight sealing of concrete surfaces is practically difficult and non-trivial.
- The hollow cylinder method (Method 2) provides a viable approach for measuring the radon diffusion coefficient in concrete.
- The determined diffusion coefficient offers valuable data for radon transport modeling in concrete structures.