Certification of the First Uranium Oxide micro-particle reference materials for Nuclear Safety and Security, IRMM-2329P and IRMM-2331P

For nuclear safeguards purposes, two new uranium oxide micro-particle isotope reference materials were certified, IRMM-2329P and IRMM-2331P, with 235 U enrichments of 3% and 5%, and 236 U abundances of 30 µg·g 1 and 60 µg·g 1 , respectively. The isotopic compositions of the base materials were measured by TIMS. The production of the uranium oxide particles was achieved using a vibrating orifice aerosol generator (VOAG) and the particles deposited on carbon planchets. Process control verification measurements on dissolved uranium oxide particles were performed by MC-ICPMS. For IRMM-2329P also the uranium amount per particle was certified by TIMS/IDMS and verified by MC-ICPMS/IDMS.