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Evaluation of MDA instant working level meters
R F Holub1, R F Droullard, T H Davis
1U.S. Department of Interior, Bureau of Mines, Denver Research Center, CO 80225.
Health Physics
|July 1, 1989
Summary
The U.S. Bureau of Mines evaluated an Instant Working Level Meter (IWLM) for measuring radon progeny. Results show inherent uncertainty of +/- 18%, with accuracy varying by gamma flux background.
Area of Science:
- Environmental Health
- Mining Safety
- Radiological Measurements
Background:
- Short-lived radon-222 progeny pose health risks in mining environments.
- Accurate measurement of radon progeny is crucial for worker safety.
- The Instant Working Level Meter (IWLM) is a commercial instrument used for this purpose.
Purpose of the Study:
- To evaluate the accuracy and reliability of a commercially available Instant Working Level Meter (IWLM).
- To determine key performance parameters of the IWLM for measuring short-lived 222Rn progeny concentrations.
Main Methods:
- Experimental determination of six evaluation parameters, including alpha and beta detector efficiencies and internal conversion factors.
- Testing of 13 IWLM instruments under controlled conditions.
- Measurement of accuracy and uncertainty at various gamma flux backgrounds.
Main Results:
- The average inherent uncertainty of the IWLM was determined to be +/- 18% (68% confidence interval).
- Coefficients of variation for counting statistics at 0.10 WL ranged from +/- 15% in low gamma flux to +/- 50% in high gamma flux backgrounds.
- Increasing the sample air flow rate to 7.5 L min-1 improved counting statistics at 0.1 WL.
Conclusions:
- The IWLM provides a means to measure short-lived 222Rn progeny concentrations.
- Instrument accuracy is influenced by environmental gamma flux.
- Optimizing sample flow rate can enhance measurement reliability.