[Natural radioactivity of underground waters: surveying of alpha and beta global activity]

Two sets of measurements used in surveying of the alpha and beta global activity of drinking water drawn from 44 abyssal wells located in the Lódź cretaceous basin are discussed. The measurement method used involved the comparison between the activities of a model source and a prepared sample of water. Radioactive isotopes Am-241 were employed in alpha and K-40 in beta measurements. In order to detect radiation, a semiconducting radiation detector Si of high purity for registration of alpha molecules and a set of two G-M counters operating in the anticoincidence circuit for registration of beta radiation were used.