DISTRIBUTION OF TERRESTRIAL GAMMA RADIATION DOSE RATE IN THE EASTERN COASTAL AREA OF ODISHA, INDIA

Terrestrial gamma radiation is one of the important radiation exposures on the earth's surface that results from the three primordial radionuclides Ra-226, Th-232 and K-40. The elemental concentration of these elements in the earth's crust could result in the anomalous variation of the terrestrial gamma radiation in the environment. The geology of the local area plays an important role in distribution of these radioactive elements. Environmental terrestrial gamma radiation dose rates were measured around the eastern coastal area of Odisha with the objective of establishing baseline data on the background radiation level. The values of the terrestrial gamma radiation dose rate vary significantly at different locations in the study area. The values of the terrestrial gamma dose rate ranged from 77 to 1651 nGy h(-1), with an average of 230 nGy h(-1). During the measurement of the terrestrial gamma dose rate, sand and soil samples were also collected for the assessment of natural radionuclides. The activities of Ra-226, Th-232 and K-40 from these samples were measured using a gamma-ray spectrometry with a NaI(Tl) detector. Activity concentrations of Ra-226, Th-232 and K-40 ranged from 15.6 to 69 Bq kg(-1) with an average of 46.7 Bq kg(-1), from 28.9 to 973 Bq kg(-1) with an average of 250 Bq kg(-1) and from 139 to 952 Bq kg(-1) with an average of 429, respectively. The detailed significance of these studies has been discussed from the radiation protection point of view.