Challenges in the determination of 210Pb in oil scale.

Radioactivity characterization of oil scale by gamma-ray spectrometry has been done for many years, often focusing on 226Ra and 228Ra. However, due to the severe disequilibrium in the 238U there also exists unusually high levels of 210Pb. Because of the 46.5 keV gamma-ray of 210Pb and the number of high-Z elements such as iron, strontium and barium correct analysis can be challenging due to severe gamma-ray self-attenuation. Our results, using a custom prepared reference material as well as standard efficiency curve, show the need for careful evaluation of 210Pb in this unusual naturally occurring radioactive material specimen.