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.