Investigation of natural and artificial radioactivity levels in travertines of the Cappadocia region in Turkey.

This study determined natural and artificial radionuclide concentrations to evaluate natural radioactivity and health risk levels of nine travertines in the Yaprakhisar and Balkayası regions in Turkey. The samples coded B1-M, B2, B5, B7, B8, and B10 represent waste derived from the Yaprakhisar travertines, as well as samples T5-M, T12, and Z1 travertines derived from Balkayası. The levels of natural and artificial radionuclide concentrations (232 Th, 40 K, and 137 Cs) were measured using a high-purity germanium (HpGe) detector system. The travertine activity ranged from 2.09 to 12.07 Bq kg-1 for 232 Th, 4.21 to 13.41 Bq kg-1 for 40 K, and 0.42-3.26 Bq kg-1 for 137 Cs. The results showed that the activity concentration values for 232 Th, 40 K, and 137 Cs were coherent with the travertine analysis results in the UNSCEAR, 2000; 2008 publications. The values obtained were lower than the average values in the UNSEAR reports. The radiological hazard parameters calculated in this study were absorbed gamma dose rate (D), radium equivalent activity (Raeq ), annual gonadal dose equivalent (AGDE), exposure dose (ER), total annual effective dose (AEDEtotal ), excess lifetime cancer risk (ELCRtotal ), gamma representative level (GRL), internal hazard index (Hin ) and external hazard index (Hex ).