Determination of Radioactivity Levels and Biological Hazards of Rock Samples Quarries Cement factories in River Nile State-Sudan

Abstract

The aim of this study was to determine environmental radioactivity level and elemental concentrations of rock and soil samples from Quarries cement factories (River Nile State -Sudan). The activity concentrations of naturally occurring radioactive materials in the 238U and 232Th decay chains and from 40K were determined by means of a gamma-ray spectrometry system using a sodium iodide (Na I) detector in a low background configuration. The ranges of activity concentrations of 238U, 232Th and 40K were found to be 3.15 ↔ 39.14, 7.42 ↔ 60.59 and 38.29 ↔ 612.59 Bq.kg-1, respectively. The results of this current study have been compared with the world mean values of 35, 30 and 400 Bq.kg-1, respectively, specified by the UNSCEAR (2000). The artificial radionuclide, 137Cs, was not observed in statistically significant amounts above the background level in the current study. Concerning radiological risk to human health, the absorbed gamma dose rate (D) in air at 1 meter above the ground surface was estimated to lie in the range 9.49 to 62.51 nGy.h-1; the outdoor annual effective dose equivalent (AEDE) was evaluated to vary from 0.012 to 0.10 mSv.y-1, with the arithmetic mean value of 0.028 mSv.y-1, which is comparable to the worldwide effective dose of 0.070 mSv.y-1. Also, the values of the Raeq and the Hex for all rock and soil samples in the present work are lower than the accepted safety limit value of 370 Bq.kg-1 and below the limit of unity, respectively. The results indicate that the radiation hazard from primordial radionuclides in all soil samples from the area studied in this current work is not significant. Additionally hazards health of human exposure of radon-222 have been determined out of the statistical analysis didn’t show any significant difference between the background concentrations of 222Rn of all cement quarries using portable device radon scout plus (SARAD). Based on the UNSCEAR guidelines for annual doses of ionizing radiation by source, the recommended upper threshold effective dose of total radon and their progenies is1mSvy-1, with a typical range of observed doses up to 0.66 ±0.11mSv/y. The mean risk of lung cancer in the cement quarries is 11.7 ± 1.98 which is much lower than the standard ICRP (170-230 lung cancer).