Measurement of radon exhalation from the ground with the aid of activated carbon and TLD

A method for measurement of radon exhalation from the ground is described. Bottles containing a TLD-crystal surrounded by activated carbon have a tube in the lid. The tubes are put into the ground and the bottles are left for 1-3 days, after which doses received by the crystals are determined in a laboratory. Knowing the background dose and calibration factor, the exhalation rate is easily calculated. The traditional method for measurement of radon exhalation with application of active carbon, involves gamma irradiation detection from radon doughters produced in adsorbed radon gas. The method described has the following advantages over the traditional one: The laboratory measurements may be performed at a later time after sampling since the decay time is not critical. In addition, the method will give a better mean value for the exhalation rate over the exhalation period. (RF)