Development of a low-level radon reference atmosphere.

Area of Science:

• Metrology
• Environmental Science
• Nuclear Physics

Background:

• Accurate calibration of radon (Rn-222) measurement devices is crucial for environmental monitoring and radiation protection.
• Existing methods for generating radon reference atmospheres have limitations in range and uncertainty below 1,000 Bq/m(3).

Purpose of the Study:

• To establish a new primary standard for generating a stable, homogeneous radon reference atmosphere.
• To extend the traceability range for commercial radon measurement devices, particularly at lower activity concentrations.

Main Methods:

• Development of a reference atmosphere using a certified radium-226 (Ra-226) activity standard.
• Precisely controlled emanation of radon (Rn-222) from the Ra-226 source to create a constant atmosphere.
• Long-term stability (>5 days) and homogeneity of the reference atmosphere were ensured.

Main Results:

• The developed reference atmosphere covers an activity concentration range from 150 Bq/m(3) to 2,000 Bq/m(3).
• The primary standard achieves a combined relative standard uncertainty of 1.1% for the reference atmosphere.
• The setup significantly reduces uncertainties in radon measurements.

Conclusions:

• The new primary standard effectively closes a gap in radon metrology, particularly for low-activity concentrations.
• This advancement enhances the accuracy and reliability of commercial radon measurement devices.
• Improved traceability in radon metrology supports better environmental and health assessments.