Preparation of pure neptunium oxide for nondestructive assay standards.

摘要

Accurate nondestructive assay (NDA) measurements, particularly with gamma spectrometry, require pure material standards. The purity of materials used as standards is verified by reliable chemical techniques, and these materials are then used to calibrate and certify NDA instruments. So that they can be used for this purpose, impure NpO(sub 2) and metal were each purified by a different procedure. The NpO(sub 2), which contained more than 2500 ppm plutonium, was purified by a double peroxide precipitation, followed by ion exchange and oxalate precipitation of the eluate. All impurities, including plutonium, were below 10 ppm in the product. The metal, which contained more than 10,000 ppm of tantalum, was dissolved in 12 M HCl and then precipitated as the Np(4) oxalate. The final product was below 100 ppm of all impurities except calcium. 1 ref., 2 tabs.