A preliminary study was carried out to determine the radioactivity concentration of 232Th, 226Ra and 40K in beach placer sands from 13 locations along the coast line of Tamil Nadu state, India. The ambient dose rates varied from 9 to 467 nGy h−1. The activity concentrations of radionuclide 232Th, 226Ra and 40K ranged from 5.2 to 683 Bq kg−1, 13 to 198 Bq kg−1 and 107 to 421 Bq kg−1, respectively. The annual effective dose rate ranges from 27 to 620 μSv y−1 and was higher at seven beaches in comparison to the UNSCEAR annual worldwide average value.
