External gamma radiation dose rates in coastal Karnataka

External gamma-ray dose rates in air have been measured using a sensitive plastic scintillometer in the environment of coastal Karnataka, on the south west coast of India, where intensive industrial activities including a nuclear power plant, a super thermal power station and a petrochemical complex are envisaged. The gamma dose rates in air range from 26 to 174 nGy h-1 with a geometric mean of 74 nGy h-1 and geometric standard deviation of 1.4. The activity of primordial radionuclides in soil samples of the region were measured using an HPGe gamma ray spectrometer and the resulting doses in air were calculated. The mean absorbed dose rate due to primordial radionuclides was 41.4 nGy h-1 with a geometric standard deviation of 1.4. A correlation was found between doses measured using scintillometer and doses estimated from the measured activity of primordial radionuclides when the cosmic ray component is taken into account. The concentration of primordial radionuclides in soil and sand show considerable variation in their vertical depth distribution in the high background area of the region.