One cubic metre NIST traceable radon test chamber

Area of Science:

• Environmental Science
• Radiological Health
• Metrology

Background:

• Accurate calibration of radon detectors is crucial for environmental monitoring and public health.
• Existing calibration methods may have limitations in terms of practicality and throughput.
• The National Institute of Standards and Technology (NIST) provides a Radon Emanation Standard for 226Ra.

Purpose of the Study:

• To develop and validate a practical radon test chamber for calibrating multiple radon detectors simultaneously.
• To establish a reliable method for generating known radon concentrations using the NIST standard.
• To assess the accuracy of the developed chamber by comparing calculated and measured radon levels.

Main Methods:

• A modified glove box was configured as a flow-through radon test chamber.
• Air was humidified and passed through the NIST Radon Emanation Standard (approx. 5000 Bq 226Ra).
• A theoretical expression was derived to calculate the radon concentration, including decay corrections for the system's volume and low flow rate.

Main Results:

• The radon test chamber successfully generated measurable radon concentrations.
• Calculated radon concentrations within the chamber showed good agreement with measurements from calibrated continuous radon monitors and passive integrating electret ion chambers.
• The system demonstrated suitability for calibrating multiple detectors concurrently.

Conclusions:

• The developed flow-through radon test chamber provides a practical and accurate method for detector calibration.
• The chamber leverages the NIST Radon Emanation Standard for reliable radon concentration generation.
• This system enhances the capacity for simultaneous calibration of various radon detection instruments.