Measurement of Radon Daughters' Radioactivities by Using Single Filtering Method
Chang, Si-Young;Ro, Seung-Gy;Hong, Jong-Sook;
ABSTRACT
A measurement has been made for the radioactivities (or concentrations) of radon daughters, i.e., RaA, RaB and RaC in airborne dust by means of single filtering method. This is to evaluate the radioactivities in terms of Ci or WL (working level) from gross alpha counts measured in the selected-time intervals after an air sample is taken from a membrane filter paper with a mean pore size of $0.8{mu}m$. This work involves determinations of standard deviation in radioactivities, radioactive equilibrium factor and ratio. It appears that a concentration of total radon daughters is $0.30{sim}2.36pCi/l;or;0.89{times}10^{-3}{sim}6.57{times}10^{-3}WL$, depending on the sampling time. Generally the highest concentration was observed around nine o'clock in a day while the lowest value was obtained around seventeen o'clock. Standard deviations based on counting statistics of RaA's, RaB's and RaC's concentrations are ${pm}57.75%,;{pm}22.32%;and;{pm}31.29%$, respectively. It is revealed that the radioactive equilibrium factor is 0.322 while the radioactive equilibrium ratio is of pattern $C_1>C_2>C_3$ in general. Here $C_1,;C_2;and;C_3$ stand for concentrations of RaA,RaB and RaC, respectively.
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