Improvement in measurements of plutonium in spent-fuel dissolver solutions

We have studied the improvement in simultaneous measurements of concentrations and isotopic compositions for plutonium in input spent-fuel dissolver solutions at a reprocessing plant by isotope dilution gamma-ray spectrometry (IDGS) technique. The IDGS technique uses the high-resolution low-energy gamma-ray spectrometry and isotope dilution method. The dissolver solutions are subsequently measured using high-resolution gamma-ray spectrometry following the fission product separations by extraction chromatography using U/TEVA·Spec resins. The improved method can simplify the separation procedure and save more than 2 hours in sample preparation time. The results of plutonium concentrations and isotopic compositions of dissolver solutions analyzed by IDGS agree very well with those obtained by traditional isotope dilution mass spectrometry. The rapid and accurate IDGS technique with the improved separation method could provide a timely, less expensive, and simpler on-site verification method for the input accountability measurements.