226Ra and natural uranium in Bulgarian mineral waters

A complex investigation on Bulgarian mineral waters from certain frequently used sources have been carried out. Specific activities of 226Ra and concentration levels of natural uranium in mineral waters samples were analyzed using nuclear and analytical methods. 226Ra is a naturally occurring radioisotope with a period of half live 1 600 years, which specific activity in water was determined through analysis of the daughter 222Rn. The measurements were carried out using a low-level liquid scintillation counting in a Packard Tri-Carb 2770 TR/SL liquid scintillation spectrometer. Uranium concentration was measured in water samples using a luminescent method. In addition to 226Ra and natural uranium, determination of gross alpha and beta activities of waters was made by means of the same liquid scintillation spectrometer. The concentrations values obtained were compared with data reported by other authors in different countries and with reference values accepted for drinking water. The expected annual effective doses for ingestion of natural uranium and 226Ra in the analysed waters were calculated.