‎M‎ehrnaz Zehtabvar - Department of Nuclear Engineering‎, ‎Faculty of Engineering‎, ‎Islamic Azad University‎, ‎Science and Research Branch‎, ‎Tehran‎, ‎Iran.
‎D‎ariush Sardari - Department of Medical Radiation Engineering‎, ‎Faculty of Engineering‎, ‎Islamic Azad University‎, ‎Science and Research Branch‎, ‎Tehran‎, ‎Iran.
‎Gh‎olamreza ‎Jahanfarnia - Department of Nuclear Engineering‎, ‎Faculty of Engineering‎, ‎Islamic Azad University‎, ‎Science and Research Branch‎, ‎Tehran‎, ‎Iran.

‎The concentration of naturally occurring radioactive materials (NORM) in surface water and irrigation wells is measured using gamma ray spectrometry by HPGe detector‎. ‎Measurement was carried out for samples that were collected over seventeen points in Tehran city and its suburbs‎. ‎The samples were prepared in compliance with the principles from irrigation wells of city‎. ‎The specific radioactivity of Ra-226‎, ‎Th-232 and K-40 were measured and the results from different locations covered a range with the minimum being below "minimum detectable activity‎" ‎up to maximum of 4.04‎, ‎and 6.85 and 4.7 Bq per liter of water‎, ‎respectively‎. ‎The accumulation of radioactive materials in the samples from southern areas of Tehran was more than that of central areas‎. ‎Also‎, ‎concentration of Ra-226 in all the samples was less than the Derived Release Limit of Canada and Environmental Protection Agency standard threshold‎.

‎Naturally radioactive materials, ‎Gamma ray spectrometry, ‎HPGe detector, ‎Tehran's water