A combined TIMS and ICP-MS study for Th0.5Np0.5O2 thorium neptunium mixed oxide analysis

This paper presented thorium and neptunium quantification of a new synthesized powder, (Th,Np)O2 mixed oxide. Thorium was quantified by Thermal Ionization Mass Spectrometry using Isotope Dilution (ID-TIMS) which is one the most accurate methodology to determine actinide mass fraction. The (sample-spike) mixture isotope ratio measured TIMS reference method for major determination, i.e. total evaporation method. An expanded uncertainty below 1% estimated Th study sources showed that main comes from spike fraction uncertainty. As Np with ID-TIMS difficult due lack commercially-available solution, obtained ICP-MS measurements gravimetric standard addition combined an analytical internal standard. developed used element initially present in sample, here Th, as measurements. helps reducing number manipulation well cross contamination, important risk when experiments are performed glove boxes. Also, equations simplified. expected about 1.8% Np. Finally, Th–Np oxide found have Th0.4836(50)Np0.5164(50)O2 stoichiometry. can be extended other complicated samples or characterization in-house certified material.