DETERMINATION OF RN-222 AND RA-226 IN AQUEOUS SAMPLES USING A LOW-LEVEL LIQUID SCINTILLATION-COUNTER

A method for measuring Rn-222 and Ra-226 in aqueous samples has been s tudied. The technique uses low-level liquid scintillation counting fro m vials containing an insoluble high efficiency mineral oil scintillat ion cocktail. A Wallac 1220(TM) Quantulus LS counter was used for all the experiments. The optimum pulse-shape discrimination value was eval uated by using the minimum detectable activity criterion for each cond ition of measurement. Experiments on the optimum volume and sample-coc ktail ratio, the influence of shaking, type of vial and diffusion of r adon from vials were carried out. The study was applied to the determi nation of very low levels of Rn-222 and Ra-226 from aqueous environmen tal samples. The results reached using this method were very satisfact ory and even better than from other more laborious procedures. Copyrig ht (C) 1996 Elsevier Science Ltd.