Gross alpha/beta measurements in water samples using liquid scintillation counter

Liquid scintillation techniques provide the detection and quantification of alpha and beta emitters in aqueous sample. Liquid Scintillation Counter (LSC) techniques using Pulse Decay Analysis (PDA) allow counting of alpha and beta radiation in the same sample simultaneously. PDA uses special pulse decay time discrimination electronics to differentiate alpha pulses from beta pulses in a liquid scintillator. In this experiment, Packard Tricarb 2770 TR-SL LSC has been used. Ultima Gold LLT produced by Packard Instrument Company was used as the liquid scintillator. The optimum counting parameters and Pulse Decay Discriminator (PDD) settings were provided for the best alpha and beta separation. PDD was verified by counting a pure alpha ''2''4''1Am and a pure beta ''3''6Cl. Spill of beta in alpha and alpha in beta was found around 0.1% at the optimum discriminator setting of 139. The counting efficiencies were 100% and 97% for alpha and beta counting respectively. Water samples were pre-concentrated to achieve the Turkish maximum permissible levels of 0.037 BqL''-''1 for gross alpha radioactivity and 0.37 BqL''-''1 for gross beta radioactivity in drinking water. After counting, the alpha and beta spill corrections were made and the gross alpha and beta radioactivities were calculated. LSC method results were compared with the gas flow proportional counters