Natural radioactivity and radiological hazard assessment of Egyptian oil ashes
2016
Mohammed, Hesham | Sadeek, Sadeek | Mahmoud, Abu Rehab | Diab, Hanan | Zaky, Doaa
Oil fly and boiler ash samples were collected from the four major Egyptian power plants in order to determine their natural radioactivity. Secular equilibrium between ²³⁸U and ²³²Th and their decay products is significantly disturbed in oil ash samples. The ²²⁶Ra/²³⁸U ratios were between 440 and 1993 with an average value of 801, indicating that the concentrations of daughters ²²⁶Ra were very high compared to the parent ²³⁸U in the oil ash samples. While, the average ratios for ²¹⁰Pb/²²⁶Ra in most samples were 1.19 ± 0.05, indicating a secular equilibrium in the ²²⁶Ra–²¹⁰Pb sub series. The natural radioactivity due to ²³⁸U and ²³²Th was found to be negligible. While the activity concentrations of ²²⁶Ra ranged from 3205 to 12,320 Bq kg⁻¹ with an average value of 9284 Bq kg⁻¹, ²¹⁰Pb ranged from 5960 to 13,930 Bq kg⁻¹ with an average value of 11,513 Bq kg⁻¹. The results are compared with the reported data from other countries. The average value of radium equivalent activity was 9308 ± 2729 Bq kg⁻¹, while the external and internal hazard indexes were found to be 25 ± 7 and 50 ± 15, respectively. All the studied radiological parameters were higher than the recommended limit by the IAEA in all ash samples.
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