ON THE CAPABILITIES OF ISOTOPE-DILUTION ALPHA SPECTROMETRY IN THE DETERMINATION OF PLUTONIUM CONCENTRATION

The determination of plutonium in spent fuel solution by isotope dilution alpha spectrometry (IDAS) is described. Two aliquots of spent fuel solution were separately spiked with well characterized solutions of Pu-238 and Pu-239. The pure spiked and unspiked plutonium solutions were obtained using a partition chromatographic technique. The alpha activity ratios of Pu-238/(Pu-239 + Pu-240) have been measured by alpha spectrometry and the concentration of plutonium calculated using isotopic composition data from mass spectrometry measurements. In parallel, the plutonium concentration was also determined by isotope dilution mass spectrometry (IDMS). The main aim of this experiment was to show the capability of IDAS compared to IDMS. Therefore the factors affecting the precision and accuracy of the IDAS method are discussed in detail. Also the outline of IDAS based exclusively on radiometric measurements (isotopic composition of plutonium by gamma spectrometry) is presented and its capabilities discussed.