Plutonium Isotopic Composition by Gamma-Ray Spectroscopy

Plutoium isotopic composition can vary dramatically depending on the application. In the nuclear fuel cycle plutonium is typically found with high burnup while low burnup is necessary for military applications. Measurement of the plutonium isotopic composition can assist in verifying that the plutonium is being used in the application as declared and is necessary in combination with a neutron-based measurement to determine the total plutonium mass. This chapter introduces the characteristics of plutonium spectra that influence isotopic measurements, describes useful spectral regions, and presents the principles of spectral analysis important to isotopic measurements. It includes descriptions of typical data collection hardware, details of data analysis methods, and descriptions of several implemented systems with examples of their accuracy and precision.