Radiological Studies in the Hot Spring Region of Mahallat, Central Iran

M. Beitollahi¹; M. Ghiassi-Nejad²; A. Esmaeli³; and R. Dunker¹ (¹Idaho State University - Dept. of Physics/Health Physics Program; ²Department of Biophysics, Tarbiat Modaress University, Tehran, Iran; ³EMC Laboratory, Electrical Engineering Department, Harbin Institute of Technology, Harbin, China)

In Mahallat Iran there are five hot springs called the “Abegarm-e-Mahallat” with a mean water temperature of 46±1 ºC used by visitors as spas. This is an elevated natural radiation area (ENRA) due to the presence of Radium-226 (226Ra) and its decay products in particular Radon-222 (222Rn). The mean concentration of 226Ra in these hot springs, measured by the emanation method ranged from 0.48±0.05 kBq m-3 to 1.35±0.13 kBq m-3. 222Rn concentrations measured in the hot springs using a liquid scintillation counter ranged from 145±37 kBq m-3 to 2,731±98 kBq m-3. In the ENRA of this region, the indoor and outdoor radon concentrations were in the range of 15 to 900 Bq m-3 and 7 to 300 Bq m-3, respectively. The absorbed dose rate in air from terrestrial gamma radiation at one meter above the ground was measured at 60 and 400 nGy h-1 for outdoor and indoor locations respectively. Radiation levels above that of normal background (around 100 nGy h-1) were mainly limited to the Quaternary Travertine in the vicinity of the hot springs. The results of environmental radiological studies in this region are presented and discussed.

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