Active measurements of indoor concentrations of radon and thoron gas using charcoal canisters.

Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine

PubMedID: 9776617

Yu KN, Guan ZJ, Young EC, Stokes MJ. Active measurements of indoor concentrations of radon and thoron gas using charcoal canisters. Appl Radiat Isot. 1998;49(12):1691-4.
Standardized charcoal canisters with diameters of 4 inch, of a type recommended by the USEPA for passive measurement of radon gas concentrations, have been modified for active air sampling. Simultaneous measurement of the concentrations of radon (Rn) and thoron (Tn) in air can be obtained by counting the areas under gamma-ray peaks. Sample results obtained in a laboratory and in a residence with different conditions are also given. The largest uncertainties are about 2% and 3% for Rn and Tn respectively. The minimum detection limits are around 2.0 Bq/m3 for both gases. If only Rn concentration is required, the measurement time can be significantly shortened.