Nondestructive determination of plutonium by gamma spectrometry and neutron well coincidence counting

Different NDA methods based on gamma ray and neutron measurements developed for the determination of Pu in solid samples is reported. In the gamma spectrometric measurements for solid samples, a method which takes advantage of the multiple γ-rays emitted by Pu and relies on the empirical relation between apparent mass of the sample and γ-ray energy was used. The method is applicable for the determination of small quantities of plutonium samples of non standard geometry by gamma ray spectrometry. The gross and coincidence neutron count rates for two different sets of standard Pu oxide powder samples were found to fall on different calibration lines. Isotopic composition of the two sets were determined using gamma ray spectrometry to obtain effective ²⁴⁰Pu content in the samples. A common calibration curve could be obtained when coincidence count rates were plotted vs. effective ²⁴⁰Pu content.