Radiometric holdup measurements: Differential mass holdup of americium and plutonium oxides during preparation of traceable non-destructive assay standards

Abstract

Traceable non-destructive assay standards containing mixtures of well characterized americium and plutonium oxides were prepared by blending weighed quantities with a diatomaceous earth matrix and encapsulating in welded zirconium cylinders. Am and Pu retained in fabrication process materials (e.g., emptied blend bottles), termed holdup, was quantified by gamma-spectroscopy in order to accurately state the total nuclear material content of the standards. The observed holdup data indicate that the common assumption that Am and Pu holdup behavior is similar does not hold up well in the case of mixed oxides.