Evaluation of MDA instant working level meters.
The U.S. Bureau of Mines and the Mine Safety and Health Administration have evaluated, for accuracy and reliability, a commercially available Instant Working Level Meter (IWLM) used by the mining industry to measure short-lived 222Rn-progeny concentrations. Six evaluation parameters were determined experimentally. These included two alpha and two beta detector efficiencies for the short-lived 222Rn progeny and two internal conversion factors. The experimental procedure detailing the evaluation technique is described in the paper. The measuring accuracy of 13 instruments is as follows: average inherent uncertainty (at least 68% confidence interval) is +/- 18%; for counting statistics and rounding at 0.10 WL (2.1 microJ m-3), coefficients of variation range from +/- 15% at low gamma flux backgrounds to +/- 50% at gamma flux backgrounds of 0.39 microC kg-1 h-1 (1.5 mR h-1). All parameters were derived theoretically and measured experimentally. All tests were conducted at a sample flow rate of 2.5 L min-1. A sample air flow rate of 7.5 L min-1 can lower the counting statistics to more acceptable levels at 0.1 WL (2.1 microJ m-3).
Holub
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RF
U.S. Department of Interior, Bureau of Mines, Denver Research Center, CO 80225.
Droullard
R F
RF
Davis
T H
TH
Cooper
W E
WE
Stewart
J F
JF
D000393:Air Pollutants / Q000032:analysis*; D000395:Air Pollutants, Occupational / Q000032:analysis*; D000396:Air Pollutants, Radioactive / Q000032:analysis*; D001729:Bismuth / Q000032:analysis; D004781:Environmental Exposure; D005069:Evaluation Studies as Topic; D007856:Lead Radioisotopes / Q000032:analysis; D008433:Mathematics; D008906:Mining; D011059:Polonium / Q000032:analysis; D011336:Probability; D011868:Radioisotopes / Q000032:analysis; D011874:Radiometry / Q000295:instrumentation*; D011886:Radon / Q000032:analysis*; D012588:Scintillation Counting
D000393:Air Pollutants; D000395:Air Pollutants, Occupational; D000396:Air Pollutants, Radioactive; D007856:Lead Radioisotopes; D011868:Radioisotopes; D011059:Polonium; D011886:Radon; D001729:Bismuth