Evaluation of naturally occurring radioactivity across the State of Kuwait using high-resolution gamma-ray spectrometry

A study of natural radioactivity from 90 different soil samples from the state of Kuwait has been carried out to ascertain the NORM concentration values across the country. The calculated activity concentrations were determined from: (i) the decays of the Ra-226, Pb-214 and Bi-214 members of the 4n+2 decay chain headed by U-238 and; (ii) the Ac-228, (212)pb and (TI)-T-208 members of the 4n chain headed by Th-232. The study also included evaluations for the U-235 decay chain with the 186 keV doublet transition used together with the measured 4n+2 activity concentration values to determine the U-235/U-238 isotopic ratios for each sample. The values for the arithmetic mean activity concentrations for 90 separate locations across Kuwait as determined in the current work were 17.2, 14.1, and 368 Bq/kg, with standard deviations of 5.2, 3.7 and 90 Bq/kg for the U-238, Th-232 and K-40 activity concentrations respectively. Measured isotope ratios for U-235/U-238. give an arithmetic mean value for all of the samples of 0.045 +/- 0.003, consistent with that expected for natural uranium. These results indicate no evidence for a radiologically significant dispersion of additional depleted uranium across the entire State of Kuwait from the 1991 Gulf War. (c) 2016 Elsevier Ltd. All rights reserved.