Procedures for the determination of Rn-222 exhalation and effective Ra-226activity in soil samples

Two methods for measuring Rn-222 exhalation and effective Ra-226 in soil sa mples were studied. In the first determination, the method employed was bas ed on the adsorption of radon onto activated charcoal and subsequent measur ement of the activity of its daughters with an HPGe (high-purity germanium) detector. In the second, vials containing an aqueous suspension of the sam ple, mixed with an insoluble high efficiency mineral oil scintillation cock tail, were measured using a low-level liquid scintillation counter. Studies of optimum sampling time, efficiency in both procedures, variation of Ra-2 26 efficiency with quenching, as well as the effect of sample amount and gr anulometry upon the quenching parameter, were carried out. The two methods were applied to the determination of Rn-226 exhalation and effective Ra-226 in environmental samples. (C) 1999 Elsevier Science Ltd. All rights reserv ed.