Evaluation of radioactivity and radiological risk in reusing granite wastes through a circular economy approach
摘要
Granites are often tested to prove their natural radioactivity emissions within the background levels; the same applies to their waste. The use of certain mineral phases extracted from granitic waste is the main point of interest, so their radioactivity needs to be assessed. In this work, scanning electron microscopic examination, X-ray diffractometry, and gamma-ray spectrometry analysis were performed to analyze the mineralogical composition as well as the radiological activities of 238U, 232Th, 226Ra, and 40 K in granite waste samples gathered from stone processing industries in Morocco. It has been demonstrated that the radioactivity levels ranged from 10 to 52 Bq.kg-1 for 232Th, from 23.79 to 49.16 Bq·kg⁻1 for 226Ra, and from 316.11 to 2033.01 Bq·kg⁻1 for 40 K. For 238U, the radioactivity level reached 181.37 Bq·kg⁻1. Furthermore, the radiological hazard indicators are within the limits except for one sample RG1 which exhibits a high value for internal hazard index inducing a significant rate of internal exposure to natural radioactivity. The outcomes of Pearson test and the principal component analysis highlight the correlation between the mineralogy and radionuclide concentrations showing that the potassium radioisotope contained in the potash feldspar is the primarily contributor to the radioactivity detected in granite waste. According to the yielded results, the significant concentration of radionuclides in granite waste may lead to an increased concentration in its by-products constituting an additional source of irradiation exposure.