Effects of fission products on demonstrated x-ray and gamma-ray NDA techniques applied to nuclear materials accounting in reprocessing

The application of demonstrated high-resolution techniques of energy-dispersive x-ray and gamma-ray spectroscopy to the assay of samples derived from plutonium reprocessing is reported. K-edge absorption densitometry with a continuum x-ray transmission source is shown to be effective for materials accounting of uranium and plutonium in fast-breeder reactor dissolver solutions. The L-edge technique with a continuum transmission source can be applied similarly beyond the first extraction. Fluorescence of K x rays with a continuum source for excitation shows some promise for uranium and plutonium materials accounting in lightwater reactor dissolver samples. The success of this technique in these applications relies on the ability to improve the statistical precision for the assay of plutonium using a new technology of high-resolution gamma-ray spectroscopy at count rates an order of magnitude greater than those previously possible. Passive gamma-ray assay techniques for determination of plutonium isotopic fractions are shown to be ineffective for all but product materials in reprocessing.