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Comparison study and thoron interference test of different radon monitors
C G Sumesh1, A Vinod Kumar, R M Tripathi
1Environmental Assessment Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400 085, India. sumeshcg@barc.gov.in
Radiation Protection Dosimetry
|July 27, 2012
Summary
Continuous radon monitors were compared for accuracy using a radon standard. Active monitors responded faster, but both active and passive types showed thoron interference, impacting radon measurements.
Area of Science:
- Environmental Science
- Radiological Health
- Instrumentation
Background:
- Radon (Rn-222) is a radioactive gas posing health risks.
- Accurate measurement of radon is crucial for exposure assessment.
- Continuous radon monitors (CRMs) offer real-time data but require calibration and interference assessment.
Purpose of the Study:
- To compare the performance of different continuous radon monitors.
- To assess the interference of thoron (Rn-220) on radon measurements.
- To evaluate the calibration and response of active and passive CRMs.
Main Methods:
- Comparison study of three passive diffusion monitors (Alpha Guard, two Radon Scout Plus) and one active discriminating monitor (RAD 7).
- Calibration using a radon emanation standard from the National Institute of Science and Technology.
- Thoron interference testing on all monitors.
Main Results:
- All instruments showed good agreement with the radon standard.
- The active monitor exhibited a higher initial response to transient radon concentrations.
- Thoron interference was observed: 9% in Alpha Guard and 4% in Radon Scout Plus monitors.
- Interference is influenced by gas diffusion area, detection volume, and sensitivity.
Conclusions:
- Continuous radon monitors generally agree well with calibration standards.
- Active radon monitors provide a quicker response to concentration changes.
- Thoron interference is a significant factor affecting radon measurements, particularly in monitors without energy discrimination.
- Monitor design parameters influence the extent of thoron interference.
