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Friday, September 9, 2016

Method for Detecting Radon in Your Basement With a Simple Geiger Counter

http://eic.nu/Tools/KusnetzMethod.htm




   
Instruments
       
Canada Inc.http://www.eic.nu

Radon Progeny Measured Using the Kusnetz Method 


In this method, an air sample is drawn through a filter for some time. The activity on the filter is then allowed to decay for at least 40 minutes, but less than 90 minutes. The activity on the filter is then counted in the TM372. The decay and counting times should be chosen so that the time between the end of sampling and the middle of counting is between 40 and 90 minutes.
This method is sometimes used by inspectors in underground mines because it is possible to take a series of samples in a short time and then evaluate them on surface. When results are needed quickly, the Rolle method is more practical and is more commonly used.
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or A.MODIFIED TSIVOGLOU METHOD Procedure. The sampling procedure is identical to that used for the modified Kusnetz method. (Actually all three methods can be used with the same filter containing sampled radon progeny.) After the end of sampling, remove the filter containing radon progeny from the filter holder and transfer it to the counting system for analysis. The standard counting intervals are 2-5, 6-20, and 21-30 min after the end of sampling. These intervals allow adequate time to transfer the filter into the counting system and record the counts from the different counting intervals. The technician or the person who performs the test is required to stand by for 30 min unless he uses automated counting equipment operated by a computer. Environmental Measurements Laboratory U.S. Department of Energy 2.2 - 55 Section 2.2, Vol. 1 Rev. 0 HASL-300, 28th Edition February 1997 B. Calculation. The equations needed to calculate the air concentrations from a 5 min sample and for the standard counting intervals are: where -----------------------
C , C , C = the concentrations of Po, Pb, and Bi, respectively (Bq m ), p -3 C = the PAEC (nJ m ) N(...) = the net counts in the intervals 2-5, 6-20, and 21-30, t -1 -1 E = fractional counter efficiency [(counts min ) /(disintegrations min )], and Q = sampling air flow rate, L min . -1 218 These coefficients were derived using 3.05 min for the half life of Po (Martz et al., 214 214 1988). The half lives used for Pb and Bi were 26.8 and 19.9 min, respectively (ICRP, 1983).

The standard deviation equations which calculate the precision for each radionuclide are: Environmental Measurements Laboratory U.S. Department of Energy 2.2 - 56 (3) (4) (5) (6)


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