Study of natural radioactivity and estimation of radiation dose in the environment of Tumkur, Karnataka, India.

The activity concentration of (226)Ra, (232)Th and (40)K was measured for soil samples collected from 34 locations of Tumkur District, Karnataka, India, using HPGe detector. The activity concentration of (226)Ra, (232)Th and (40)K varied from 9.6 to 71.6, 12.3 to 333.3 and 194.3 to 1527.7 Bq kg(-1) with an average value of 33.15, 123.01 and 877.76 Bq kg(-1), respectively. The absorbed and annual effective outdoor doses were found to be highest at Ponnasamudra with 258.98 nGy h(-1) and 317.62 µSv and lowest at Sira with 36.42 nGy h(-1) and 44.67 µSv, respectively. The external hazard index ranged from 0.21 to 1.58 with an average of 0.75. It was significant in 11 locations as it exceeded unity.