Measuring of radioactive contamination of ground water in Tehran Province

Due to the importance of water in human life, measurement of radioactive materials as well as chemical and microbiological pollutions is essential. In popular laboratories of world, this task is commonly performed by primarily measuring the gross Alpha/Beta activity. In this thesis, in order to analyze the quality and safety of water supplies in Tehran province, 31 samples of ground water were collected by Systematic Sampling method. To determine gross alpha/beta activity, all samples were prepared by the evaporation way and counting was performed by gas proportional detector. Since the determination of tritium is impossible in this way, water samples were distilled for counting by Quantulus Ultra Low-level Liquid Scintillation Counter (LSC). Because of Alpha-emitter elements risk in water, Alpha spectroscopy system equipped with Passivated Implanted Planar Silicon (PIPS) detector, was used to measure the gross Alpha activity more precisely and to determine the radiation of long-lived radionuclides in 238U and 232Th decay series.

In regard to the minimum detectable activity and accuracy of measuring systems, it is deduced that the gross Alpha/Beta activity, the amount of tritium and natural Alpha-emitters are at acceptable level in the ground water samples of Tehran province. Therefore no evidence of radioactive contamination is confirmed.

Measuring of radioactive contamination of ground water in Tehran Province Keywords:

Radioactive materials in water , gross alpha/beta activity , Tritium , liquid scintillation counting , alpha spectrometry