Nuclear forensic analysis of an unknown uranium ore concentrate sample seized in a criminal investigation in Australia

•Unknown radioactive powder identified in nuclear forensic investigation.•Rare earth element pattern was key nuclear forensic signature.•U, Sr and Pb isotope ratios were also key nuclear forensic signatures.•Multivariate statistical analysis confirmed nuclear forensic result.

Early in 2009, a state policing agency raided a clandestine drug laboratory in a suburb of a major city in Australia. During the search of the laboratory, a small glass jar labelled “Gamma Source” and containing a green powder was discovered. The powder was radioactive. This paper documents the detailed nuclear forensic analysis undertaken to characterise and identify the material and determine its provenance. Isotopic and impurity content, phase composition, microstructure and other characteristics were measured on the seized sample, and the results were compared with similar material obtained from the suspected source (ore and ore concentrate material). While an extensive range of parameters were measured, the key ‘nuclear forensic signatures’ used to identify the material were the U isotopic composition, Pb and Sr isotope ratios, and the rare earth element pattern. These measurements, in combination with statistical analysis of the elemental and isotopic content of the material against a database of uranium ore concentrates sourced from mines located worldwide, led to the conclusion that the seized material (a uranium ore concentrate of natural isotopic abundance) most likely originated from Mary Kathleen, a former Australian uranium mine.