Measurement of terrestrial gamma radiation dose rate and radioactivity levels in the southern hilly regions of Manipur, India

Abstract

The terrestrial gamma radiation levels and associated dose rates were estimated at 120 different sites with 12 soil samples in the southern hilly regions of Manipur, India, consisting of Churachandpur and Chandel district, by using NaI (Tl) scintillator-based Micro-R survey meter and high-purity germanium detector. The observed annual effective dose in this study area ranges from 0.37 to 1.51 mSv/y, with a mean value of 0.85 ± 0.16 mSv/y. Whereas Churachandpur and Chandel districts showed a mean value of 0.88 ± 0.18 (ranges: 0.67 to 1.51) mSv/y and 0.83 ± 0.14 (ranges: 0.37–1.24) mSv/y, respectively. This southern region of Manipur shows slightly higher values of annual effective dose as compared with the earlier reported value of about 0.7 mSv/y for the central valley region of Manipur, and world average value of about 0.4 mSv/y, reported by United Nations Scientific Committee on the Effects of Atomic Radiation (2000). The soil analysis for226Ra,232Th, and40K of this area gives an average activity concentration of 44.3 (ranges: 23.8–78.6) Bq/kg, 169.1 (ranges: 83.6–305.1) Bq/kg, and 1489.1 (ranges: 752.5–2426.8) Bq/kg, respectively.

Keywords

• annual effective dose
• chandel
• churachanpur
• external exposure index
• natural radioactivity