Investigation of radioactivity levels in the indoor and beach samples of Kollam, Kerala and the assessment of radiological hazard indices

The beach sand on the south-west coast of Kerala, India is one of the richest sources of thorium in the world. This causes enhanced natural radioactivity in the nearby locations due to the presence of various radionuclides. Natural radioactivity levels in 48 soil samples collected from houses and 78 samples collected from the beach along the coastal areas of Kollam, Kerala were analyzed using the gamma-ray spectrometer The radium and thorium content in the samples measured from houses is more than that of beach samples and it varies as 54.7 f 1.0 - 21720.1 f 19.2 Bq kg-1 and 110.3 f 1.1 - 95623 f 21.8 Bq kg-1 for radium and thorium respectively. The ambient gamma-ray dose in the outdoor atmosphere was measured using a survey meter and TLDs and the measurements showed a strong positive correlation (R2 = 0.92). The vertical profile studies in beach sand samples were done for distances in 4 locations at three intervals. The results of vertical profile studies show that the activity concentration of radium and thorium at 30-40 cm depth was greater than that at 0-10 cm and less than that at 60-70 cm.