TY - JOUR T1 - Study of distribution of 226Ra, 232Th and 40K in different rock formations and their dose estimation in and around Chickmagalur, India TT - JF - Int-J-Radiat-Res JO - Int-J-Radiat-Res VL - 11 IS - 3 UR - http://ijrr.com/article-1-1061-en.html Y1 - 2013 SP - 183 EP - 187 KW - Radionuclides KW - Igneous rock KW - metamorphic rock and effective dose. N2 - Background: The concentrations of radionuclides like 226Ra, 232Th and 40K and the dose rate are measured in igneous and metamorphic rock formations in and around Chickmagalur. A total of 236 samples from 13 different locations around study area were analyzed. Materials and Methods: The activity concentrations of the three radioactive elements were determined for mean period of 25000 s using HPGe (GMX - 10190) detector and the dose calculations were made using standard formulae. Results: The mean activity concentrations in igneous rocks recorded were 36.6 Bqkg-1, 73.2 Bqkg-1 and 992.3 Bqkg-1 for 226Ra, 232Th and 40K respectively. The mean activity concentrations in metamorphic rocks were 17.2 Bqkg-1, 28.1 Bqkg-1 and 617.8 Bqkg-1 for 226Ra, 232Th and 40K respectively. Assuming 20% occupancy factor, the corresponding mean annual effective dose due to igneous and metamorphic rocks were 169.6 µSv and 90 µSv respectively. Conclusion: The concentrations of radionuclides were found to be in similar with global and Indian average (1-3). M3 ER -