Assessment of Terrestrial Gamma Radiation Dose Rate and Radioactivity Levels in Eastern Hilly Region of Manipur, India

Human body have always been exposed to natural radiation throughout their period of existence, which are out of control. Natural radioactivity levels vary across different regions due to geological factors. Assessment of radioactivity on various regions is important because high levels of radioactivity may increase stochastic effects to animal including human and genetic mutation to plants as well.

The terrestrial gamma radiation levels and associated dose rates were estimated at 140 different sites with 18 soil samples in the eastern hilly region of Manipur, India, consisting of Ukhrul and Chandel district, by using NaI(Tl) scintillator based Micro R-survey meter and high purity germanium detector.

The observed dose rate in this study area ranges from 35.0 to 142.0 nGy/h with a mean value of 86.9 ± 19.0 nGy/h. Whereas, Ukhrul and Chandel districts showed a mean value of 81.8 ± 13.5 (ranges: 56.1 to 130.0) nGy/h and 92.1 ± 22.1 (ranges: 35.0 to 142.0) nGy/h respectively. The soil analysis for 226Ra, 232Th and 40K of this area gives an average activity concentration of is 31.0 (range: 21.3 – 55.4) Bq/kg, 62.6 (range: 47.3 – 92.4) Bq/kg and 827.6 (range: 754.9 -966.2) Bq/kg respectively.

The effective dose rates of the study sites are observed to be slightly higher than the world average of about 0.5 mSv/y. The soil analysis for 226Ra, 232 Th and 40K activity concentration of this eastern hilly region of Manipur is observed relatively higher compare with global and national average values.

Understanding the implications of measured radioactivity concentrations reported by researchers, is crucial for devising strategies to mitigate potential hazards associated with it. Special and effective measures may be taken up on regions with high levels of natural radioactivity to protect both human health and ecological balance.