Radioactivity and Risk Assessment with Uncertainty Treatment for Analysis of Black Sand Minerals

Abstract

Precise radiological analysis of environmental, ores, nuclear materials and minerals samples is of great value for monitoring and surveillance objectives. The information deduced from the analysis can be used to identify the origin and nature of the accompanied activities. This work focuses on analysis of some black sand ore samples to identify and quantify their radioisotopes and potential risk. The analysis can provide useful information about the environmental transport mechanism and about the sources of radionuclides in the studied area; Rashid city coast, Egypt. To achieve this target, a Non‐destructive gamma spectrometer (NDGS) was used to trace and amount the radioisotopes types and activities. The efficiency was calculated with uncertainty treatment. The specific activity with uncertainty assessment of 238U, 232Th decay series and 40K of these samples were varied from 72.2 to 252.4 with average value 111 ± 25 Bq·kg–1, 94.2 to 579.8 with average value 140 ± 22 Bq·kg–1 and 427.9 to 527.5 with average value 475 ± 36 Bq·kg–1 respectively. The mineralogical signature of the analyzed samples (XRD) indicates that the samples are mainly composed of ilmenite, zircon, rutile, sphene and monazite. The potential risk assay shows that the hazard parameters of these samples; the Absorbed Gamma Dose Rate (AGDR), Gamma Activity Index (Iγ), Annual Effective Dose Rate Equivalent (AEDRE), Radium equivalent, External and Internal Hazard Index (Hex and Hin) are of specific characteristics. The total absorbed gamma dose rate and the annual effective dose due these samples were found to be with average values 158 ± 24 (nGy/h) and 195 ± 29 (μSv/y) which are higher than the world average value of 59 nGy/h and 70 μSv/y respectively. The results obtained are important to establish baseline levels to detect any upcoming changes due to any activities. It can be observed that the studied area has elevated thorium and uranium content. The relatively high dose rate will be considered as a spa for the physical therapy such as treatment of some skin diseases and rheumatoid.