Assessment of natural radioactivity concentrations and gamma dose rate levels in Kayseri (Turkey)

This study assesses the level of background radiation for Kayseri province of Turkey. Natural radionuclide activity concentrations in soil samples were determined using high-resolution gamma spectroscopy. Outdoor gamma dose measurements in air at 1 m above ground level were determined using a portable gamma scintillation detector. The obtained results of uranium and thorium series as well as potassium ( 40K) are discussed. The present data were compared with the data obtained from different areas in Turkey. From the measured gamma-ray spectra, the average activity concentrations were determined for 238U (range from 3.91 to 794.25 Bq kg-1), 232Th (range from 0.68 to 245.55 Bq kg-1) and 40K (range from 23.68 to 2718.71 Bq kg-1). The average activity concentrations of 238U, 232Th and 40K were found to be 35.51, 37.27 and 429.66 Bq kg-1, respectively, and 11.53 Bq kg-1 for the fission product 137Cs. The highest values of 238U, 232Th and 40K concentrations (794.25 Bq kg-1, 245.55 Bq kg-1, 2718.71 Bq kg-1, respectively) were observed in abnormal samples at Hayriye village. The average outdoor gamma dose rate in air at 1 m above the ground was determined as 114.43 nGy h-1. Using the data obtained in this study, the average annual effective dose for a person living in Kayseri was found to be about 140.34 μSv. (authors)