Granulation effects on the radon emanation rate

Area of Science:

• Environmental Science
• Radiological Protection
• Materials Science

Background:

• Radon-222 (Rn-222) is a naturally occurring radioactive gas that poses health risks, particularly in indoor environments.
• Building materials can be a source of indoor radon, influenced by their composition and physical properties.
• Understanding radon emanation from building materials is crucial for mitigating indoor radiation exposure.

Purpose of the Study:

• To investigate the effect of granulation (particle size) on radon emanation rates from various building materials.
• To quantify the radon emanation coefficient for ceramic plates, sand, red brick, and siporex brick at different granulations.
• To identify which building materials are most susceptible to granulation effects on radon release.

Main Methods:

• Materials were processed using a ball mill to achieve varying granulation levels.
• Particle size distribution was analyzed using a Mastersizer 2000 particle size analyzer.
• Radon-222 concentration buildup in a closed chamber was measured over time using an alpha spectrometer (RAD7).

Main Results:

• Siporex brick exhibited the highest radon emanation coefficient (27%) when its grain size was smallest (0.34 µm).
• Ceramic plates showed a negligible granulation effect, with very low emanation coefficients (around 0.4%).
• The strongest influence of granulation on radon emanation rate was observed for siporex brick samples.

Conclusions:

• Granulation significantly affects radon-222 emanation from building materials, with finer particles generally leading to higher emanation.
• Siporex brick is particularly sensitive to granulation effects on radon release compared to ceramic plates.
• Material-specific properties dictate the extent to which particle size influences radon emanation.