Year
1987
Abstract
A 3000-liter feed adjustment tank containing over 2400 L of uranium solution was assayed for its contents using the double spiking technique of isotope dilution mass spectrometry. Lutetium was the double spike, with the natural element used as the initial spike and enriched 176-Lu as the second. The ability of a remote sampling system was evaluated for its ability to introduce the lutetium and also to produce homogeneous sample solutions. The system was found to be satisfactory. Volumes of the tank can be measured to a precision of about 0.2%. The concentration of uranium was measured as 154.5 g/L uranium, thus giving a total of 382.3 kg in the tank as compared to the plant's best estimate of 383 kg. Uranium measurements were subjected to internal calibration calculations, with 233-U and 236-U being used as the reference isotopes. A diversion of 5% of the tank contents was simulated to evaluate the method's sensitivity in this regard. The ability of this method to give timely results of good precision makes it a strong candidate for use in material balance and inventory accountability applications; it also has potential use in quality assurance areas.