Gamma index level and radiological hazards of fly ash samples from thermally powered facilities

Abstract

This study investigated the distribution of natural radionuclides (²³⁸U, ²³²Th, ⁴⁰K) and Gamma Index Level (I_γr) in fly ash samples collected from two thermal power stations in Iraq: Al-Musaaeb and Al-Nasiriyah. The primary aim was to evaluate the radiological hazards associated with these samples. The activity concentrations of the radionuclides were comparable to those reported in the literature but occasionally exceeded the global safety limits set by UNSCEAR. The Pearson correlation coefficients for ²³⁸U and I_γr were notably high (0.58 for Al-Nasiriyah and 0.87 for Al-Musaaeb), which is consistent with previous studies. The study calculated the annual effective dose (AEDE) to be between 0.44 and 1.3 mSv/y (average 0.71 mSv/y) for Al-Musaaeb, and 0.29–0.53 mSv/y (average 0.40 mSv/y) for Al-Nasiriyah. The excess lifetime cancer risk (ELCR) values ranged from 1.53 to 4.55 nGy/h (average 2.49 nGy/h) for Al-Musaaeb and 1.00–1.85 nGy/h (average 1.39 nGy/h) for Al-Nasiriyah. Radiological hazard assessments indicated that most indexes were within acceptable global reference levels, suggesting no significant radiological threat from the samples. Therefore, fly ash can be safely used in various applications. In addition, this study underscores the importance of monitoring fly ash from thermal power plants for potential environmental radiation risks and contributes valuable data for regional safety evaluations.