An interlaboratory collaboration to determine consensus 231Pa/235U model ages of a uranium certified reference material for nuclear forensics

Application of the 231Pa/235U radiochronometer for nuclear forensic investigations is challenged by a lack of certified reference materials with 231Pa/235U model purification dates. The Japan Atomic Energy Agency, Los Alamos National Laboratory, and Lawrence Livermore National Laboratory completed an interlaboratory study measuring 231Pa/235U model ages of New Brunswick Laboratory CRM U100. Results from independent laboratories were combined to calculate a consensus 231Pa/235U model purification date for CRM U100 of March 26, 1959 ± 237 days. This 231Pa/235U consensus date for CRM U100 may be used by the nuclear forensic community for quality control of 231Pa/235U radiochronometry measurements of unknown materials.