Environmental Natural Gamma Radiation Level and Activity of Uranium-238, Thorium-232 at Different Places Measured Using NaI (Tl) Scintillation Detector

Natural and cosmogenic radioactive nuclides are present all over the world. Radiation emitted from these nuclides forms the natural background. Exposure to ionizing radiation from natural sources is a continuous and unavoidable feature of life on the earth. The environmental effective gamma radiation dose from terrestrial and cosmic radiation at height one foot above the earths surface in open atmosphere has been measured at twenty six different places in Sindhudurga district of Maharashtra state (INDIA) (15022-16024N; 73012-74012E) by using 2X2 NaI (Tl) scintillation detector. The effective gamma radiation dose at different locations varies between 0.286 mSv/y to 0.804 mSv/y, with an average of 0.524 mSv/y. The activity of U238 and Th232 has been measured using gamma ray spectroscopy. The U238 activity varies from 0.466 KBq/m2 to 1.133 KBq/m2 with mean value of 0.751 KBq/m2. The Th232 activity varies from 0.552 KBq/m2 to 1.267 KBq/m2 with mean 0.8466 KBq/m2. The U238 to Th232 activity ratio varies from 0.494 to 1.2 with mean 0.886.