ACCURATE QUANTIFICATION OF DRIED RESIDUE THIN FILMS USING X-RAY FLUORESCENCE, C.G. Worley, G.J. Havrilla, pp. 392-397

An XRF specimen preparation method was developed to quantify the concentration of gallium in plutonium metal while minimizing the risk of contaminating the instrument with radioactive material. To ensure that homogenous specimens are examined, plutonium is dissolved in dilute HCl and HNOJ prior to analysis. In the preliminary work here, non-radioactive aqueous gallium standards were prepared, and zinc was added as an internal standard to improve the accuracy and precision. Aliquots from these solutions were cast on Mylar XRF films and air dried prior to analysis. Two methods of casting the solutions were evaluated: 1) casting as a thin layer using a surfactant to wet the support film and 2) casting multiple small spots on the support film. Aqueous gallium standards were prepared and cast as dried residue specimens using each method. These specimens were then analyzed, and calibration curves were prepared. Highly linear calibrations were obtained for each preparation method when zinc was used as the internal standard (RMS values 51% of the standards concentration range in both cases). Based on this preliminary work, this dried residue process appears very promising for the accurate quantification of gallium in plutonium.