Radiometric analysis of Chinese commercial granites

Summary

Due to the widespread use of granites as building and ornamental materials, measurements of ²²⁶Ra, ²³²Th and ⁴⁰K activities in commercial granites have been carried out using a NaI(Tl)g-ray spectrometer with a matrix-inversion-based spectral stripping technique. The concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in Chinese commercial granite range from 14.5 to 204.7 Bq^. kg^-1, 16.7 to 186.7 Bq^. kg^-1and 185.7 to 1745.6 Bq^. kg^-1, respectively. The mean values of the activity concentrations of ²²⁶Ra, ²³²Th and ⁴⁰K in red and pink commercial granites are all higher than those in black and gray commercial ones. The radium equivalent activity (Ra_eq), the external hazard index (H _ex), the internal hazard index (H _in ) and the annual gonadal dose equivalent (AGDE) were also calculated and compared to the international recommended values. Six types of red commercial granites (CBR, MLR, QXR, PBR, JXR, LQR, YDR and TSR) of China do not satisfy the universal standards.