Application of ultra-low level liquid scintillation to the determination of 222Rn in groundwater

A procedure for the determination of 222Rn in environmental water samples using liquid scintillation counting (LSC) was applied. The extractive scintillator RADONSR and an ultra-low background 1220 QuantulusTM were used. A minimum detectable activity of 0.1 Bq x l-1 in 20 ml was found with low-diffusion polyethylene vials and 200 minute measurement time. Quenching effects and possible interferences due to the existence of other radionuclides in the extraction process were studied. The procedure was controlled by gamma-ray spectrometry of the 222Rn daughters. Applications to environmental samples collected from spas, wells, and public springs in Extremadura (Spain) are presented. (author)