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Comparative Analysis of Radiological Hazards Indices from Residual Radioactivity around Mika Uranium Mining Site in North-Eastern Nigeria. |
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PP: 59-65 |
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doi:10.18576/jrna/110108
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Author(s) |
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Soja Reuben Joseph,
Umar Ibrahim,
Abdullahi A. Mundi,
Idris M. Mustapha,
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Abstract |
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| Uncontrolled mining activities can increase the background radiation to members of the public by facilitating the release of natural radioactivity from the host materials to the environment as a result of the extraction of mineral ores, resulting in undue radiation hazards in the long run. This study evaluated the comparative analysis of Radiological Hazards indices from Residual Radioactivity to the residents around Mika Uranium mining site in North Eastern Nigeria, by performing analytical evaluation of radiological hazard indices parameters and evaluating the Offsite Dose and excess cancer risk using the RESRAD Offsite computer code from residual radioactivity concentrations of 238U, 232Th and 40K in soil samples around Mika Uranium Mining site in Taraba State, North Eastern, Nigeria. The representative soil samples were collected using systematic random sampling techniques. The soil samples collected were analyzed for radioactivity concentrations of 238U, 232Th, and 40K using a Sodium Iodide NaI (Tl) detector at the Centre for Energy Research and Training (CERT), Ahmadu Bello University, Zaria, Nigeria. Comparing these results with international recommended values, the mean activity concentration of 40K (457.44 Bq/kg) is higher than the global average of 420 Bq/kg reported by UNSCEAR (2000), while the mean 238U (15.68 Bq/kg) and 232Th (12.53 Bq/kg) fall below the worldwide average values of 33 Bq/kg and 45 Bq/kg respectively. The mean absorbed dose rate (33.89 nGy/h) and Raeq (69.22 Bq/kg) are within safe global limits. The external hazard index (0.186) is far below unity, indicating a negligible external gamma hazard. The mean AEDE (0.042 mSv/y) is much lower than the 1.0 mSv/y global safety limit. The mean ELCR (0.145 × 10⁻³) is within the safe band but indicates a slight elevation in potential cancer risk. The result of simulation using the RESRAD Offsite computer code shows that the highest total offsite dose is 4.99e-03mSv/yr after 70 years. Although the total dose is below the EPA dose limit of 0.1mSv/yr for inhalation, the dose has remained stable after 70 years and remains stable due to the long half-lives of NORM radionuclides. The doses recorded were all lower than the EPA dose limit of 0.1mSv/yr, indicating that the inhalation doses emanating from residual radioactivity from the Mika uranium mining site considered in this study have less impact on offsite residents in the long run. However, the danger of radiation exposure and its impacts must be understood by the population living near the mining sites, as no radiation exposure is safe since accumulation of low exposure dose can result in stochastic effects. |
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