Activity concentrations of 224Ra, 226Ra, 228Ra and 40K radionuclides in refinery products and the additional radiation dose originated from oil residues in Turkey

A total of 56 crude oil, refinery product, waste water, sludge and scale samples collected from three refineries were measured by gamma-ray spectrometry. Except for nine samples, all refinery product samples were found to have activity concentrations below the minimum detectable activity (MDA) values. The maximum (224)Ra, (226)Ra, (228)Ra and (40)K activity concentrations in crude oil and refinery product samples were measured as 11.7 ± 4.5, 14.9 ± 3.5, 11.6 ± 4.5, 248.5 ± 18.5 Bq kg(-1), respectively. The maximum (224)Ra, (226)Ra, (228)Ra and (40)K activity concentrations in scale, sludge and water samples were measured as 343.7 ± 11.8, 809.2 ± 29.0, 302.5 ± 21.6, 623.0 ± 80.9 Bq kg(-1), respectively. Radium equivalent activities of the residue samples were calculated up to 1241.8 ± 42.4 Bq kg(-1). The maximum activity concentration index and the alpha index were found to be 4.2 and 4.0, respectively. The annual effective doses of residue samples were calculated below the permitted dose rate for the public, i.e. 1 mSv y(-1).