Assessment of radiological risk factors in the Zonguldak coal mines, Turkey

Radon concentrations in the working sections of the Zonguldak coal mines were determined and activity concentration measurements of natural 226Ra, 232Th and 40K radionuclides were performed with high resolution passive gamma-ray spectrometry for coal samples collected from these sections. The 222Rn concentration was found to be between 15 and 78 Bq m−3, well below the action limit of 1000 Bq m−3 according to ICRP65. The annual effective dose to miners due to inhalation of radon was determined to be between 60 and 312 µSv. Activity concentrations of 226Ra, 232Th and 40K in the coal samples were found to be 13–164, 13–215 and 344–1100 Bq kg−1, respectively. Radium equivalent activity, dose rate in air and average annual effective dose equivalents were calculated in the range of 66–602 Bq kg−1, 32–265 nGy h−1 and 30–244 µSv, respectively. The resultant total annual effective doses can be used to minimise the radiological risk to the coal miners.