Developing ²²⁶Ra and ²²⁷Ac age-dating techniques for nuclear forensics to gain insight from concordant and non-concordant radiochronometers

The model age or 'date of purification' of a nuclear material is an important nuclear forensic signature. In this study, chemical separation and MC-ICP-MS measurement techniques were developed for ²²⁶Ra and ²²⁷Ac: grand-daughter nuclides in the ²³⁸U and ²³⁵U decay chains, respectively. The ²³⁰Th-²³⁴U, ²²⁶Ra-²³⁸U, ²³¹Pa-²³⁵U, and ²²⁷Ac-²³⁵U radiochronometers were used to calculate model ages for CRM-U100 standard reference material and two highly-enriched pieces of uranium metal from the International Technical Working Group Round Robin 3 Exercise. Results demonstrate the accuracy of the ²²⁶Ra-²³⁸U and ²²⁷Ac-²³⁵U chronometers and provide information about nuclide migration during uranium processing. (author)