QUANTIFICATION OF GALLIUM IN DRIED RESIDUE SAMPLES BY XRF: AN IMPROVED SAMPLE PREPARATION METHOD FOR ANALYZING PLUTONIUM METAL, C.G. Worley, pp. 421-426

A novel XRF sample preparation method was investigated to quantify the concentration of gallium in plutonium metal and minimize the possibility of contaminating the instrument with radioactive material. To prepare homogenous specimens and to add an internal standard, the plutonium must first be dissolved. The currently established method then entails removing the plutonium by chromatography and analyzing the gallium remaining in solution. In the work presented here, plutonium solution aliquots containing zinc as an internal standard were cast onto Mylar, dried, and analyzed by XRF. Aqueous standards containing gallium and zinc were first cast as dried residues, and these residue standards were analyzed and calibrated. More recently aqueous standards containing plutonium, gallium, and zinc were prepared, cast as dried spots, and calibrated. Very linear calibrations were obtained for both sets of standards when zinc was used as the internal standard (RMS values ≤1% of the standards concentration range). Hence, this dried residue process appears very promising for quantifying gallium in plutonium metal.