226Ra and 228Ra in scale and sludge samples and their correlation with the chemical composition

In order to contribute to a future waste management policy related to the presence of technologically enhanced natural occurring radioactive material (TENORM) in the Brazilian petroleum industry, the present work presents the chemical composition and the 226Ra and 228Ra content of sludge and scales generated during the offshore E and P petroleum activities in the Campos Basin, the primary offshore oil production region in Brazil. The 226Ra and 228Ra content on 36 sludge and scales samples were determined by gamma-spectrometry. Based on X-ray diffractometry results, a chemical analysis schema for these samples was developed. The results have shown that scales are 75% barium and strontium sulfates, with a mean 226Ra and 228Ra content of 106 kBq kg−1 and 78 kBq kg−1, respectively. On the other hand, sludge samples have a much more complex chemical composition than the scales. The 226Ra and 228Ra content in sludge also varies much more than the content observed in the scales samples and ranged from 0.36 to 367 kBq kg−1 and 0.25 to 343 kBq kg−1, respectively.