Distribution of naturally occurring radioactive materials at three coastal areas of Tamil Nadu, India: a comparative study

The activity concentrations of the primordial radionuclides in sediment and ambient gamma were studied along the coast of three different background radiation areas of Tamil Nadu. The study was carried out on Kanyakumari (HBNRA), Kalpakkam (NBNRA), and Parangipettai (LBNRA) beach sediments. The primordial radionuclides in the beach sediments were quantified using a gamma-ray spectrometer. The ambient gamma (nSv h−1) of the Kanyakumari coastal lines ranged from 0.03 to 6.72; at Parangipettai, it varied from 0.01 to 0.11 and from 0.05 to 3.71 at Kalpakkam. The average annual effective dose was found to be 3443.4, 819.1, and 34.9 (nSv/y) at Kanyakumari, Kalpakkam, and Parangipettai coast, respectively. The comparative study of the activity concentration of the radionuclides, 40K, 238U, and 232Th from the beach sediments of Kanyakumari district and Parangipettai showed large variation especially 238U, and 232Th activity. Higher concentration of these radionuclides at that the Kanyakumari coast can be attributed to the monazite deposits. It was also found that Kanyakumari beach sediments had lower 40K levels than Parangipettai and Kalpakkam samples.