Year
1989
Abstract
A rapid ion exchange/direct current argon plasma (DCAP) spectrometry method is now being applied at the Savannah River Site to provide faster, more reliable assay of key metallic impurities in plutonium metal. These measurements are essential for nuclear materials accountability and enhanced process control. Impurity assays must be performed to ensure that plutonium product specifications are met and to determine the 100% - impurities plutonium assay used in shipper/receiver calculations. Separation of impurities from plutonium metal is required prior to measurement by spectral techniques since the complex emission spectra of plutonium interferes with the impurity emission lines. A modified commercial vacuum system is used to perform the ion exchange separation in a glovebox. Since column flow rates are 10-15 times that of conventional ion exchange, purification time is relatively short. Separation efficiency is maintained by using small particle resin. The DCAP method is faster and provides much better accuracy and precision than the previously used carrier distillation d.c. arc spectrographic technique. The DCAP instrument has a much greater linear dynamic range than d.c. arc, does not require plutonium matrix standards for instrument calibration, and requires much less space than a d.c. arc spectrograph. Sixteen key metallic impurities are routinely measured using the ion exchange/DCAP spectrometry method.