Natural radioactivity distribution in geological matrices around Kaiga environment

The activity and absorbed dose rate of the naturally occurring radionuclides, viz. 238U, 232Th and 40K were determined in soil and rock samples collected around Kaiga site. The mean activity levels (Kaiga soil) of naturally occurring 232Th are comparable with that in worldwide soil, while concentrations of 238U and 40K are lower than those in worldwide soil. The absorbed dose rate in outdoor air ranged 20-58 nGy x h-1 with a mean of 33.3 nGy x h-1, which is below the world average of 60 nGy x h-1. The total effective dose rate in outdoor air for soils ranged 25.6-74.4 μSv x y-1 with a mean of 43.0 μSv x y-1. The estimated dose rate at Kaiga is comparable with that estimated at Kakrapar and Rawatbhata and much less than that estimated at coastal sites of India. (author)