Investigation of gamma dose and enrichment of 238 U/ 232 Th in manufactured sand collected from Tamil Nadu using a gamma ray spectrometer

Manufactured sand (M-sand) is widely used as an alternative to river sand in construction, making the assessment of its natural radioactivity essential for radiation safety. In this study, twenty M-sand samples collected from the Dharmapuri district, Tamil Nadu, were analyzed using NaI(Tl) gamma-ray spectrometry to determine the activity concentrations of 238U,232Th, and 40K and evaluate the associated radiological hazards. The measured activity concentrations ranged from BDL-80 Bq kg−1 for 238U, BDL-58 Bq kg−1 for 233Th, and 414-567 Bq kg−1 for 40K, with corresponding mean values of 25,44, and 482 Bq kg−1, respectively. Although the mean activity concentration of 232Th and 40K were slightly higher than the worldwide average values reported by UNSCEAR, all calculated radiological hazard indices remained within the recommended safety limits. Furthermore, the average 232Th/238U concentration ratio indicated thorium enrichment in the study area. Overall, the findings demonstrate that the investigated M-sand samples are radiologically safe for use as construction materials and provide valuable baseline data for future environmental radioactivity monitoring and radiation safety assessments.