Occurrences of NORMS and 137Cs in soils of the Singhbhum region of Eastern India and associated Radiation Hazard

Naturally occurring radioactive materials (NORMS) and fallout Cs-137 were estimated in surface soils front the highly mineralized Singhbhum region of Eastern India. The activity concentrations varied from 50.67-109.14 Bq/kg (U-238), 48.12-142.55 Bq/kg (Ra-226), 28.73-89.78 Bq/kg (Th-232), 494.84- 1121.36 Bq/kg (K-40) and 1.8-7.48 Bq/kg (Cs-137). Correlation between radionuclides was studied. Th-232/U-238 concentration (Clark value) was also calculated. Radiation hazard for the samples was assessed by radium equivalent activity (Ra-eq), external hazard index (H-ex), internal hazard index (H-in) and absorbed gamma dose rate (D). Ra-eq values ranged front 216-263 Bq/kg, H-ex values front 0.58-0.71 Bq/kg, H-in values from 0.73-1 Bq/kg and D values front 100-121 nGy/h. Calculated and observed dose rates in air were compared with the help of parametric and non-parametric tests. The tests showed significant difference between the calculated and observed dose rates.