Measurement of plutonium in large concrete radioactive waste packages by photon activation analysis

Characterization of nuclear waste packages is crucial to select the best mode of storage. Passive and active non-destructive methods are well-adapted to this problem and their coupling can be extremely useful in order to optimize data analysis. Photon Activation Analysis (PAA), based on the photofission process and on the detection of delayed particles emitted after this reaction, is a powerful tool for the analysis of bulky concrete waste packages. Methods developed around PAA allow to locate, identify and quantify the mass of actinides (²³⁵U, ²³⁸U, ²³⁹Pu) present in a given package in order to estimate its α-activity. In this article, we present experimental and simulated results obtained in PAA during the characterization of a real nuclear waste package in the SAPHIR facility (Active Photon and Irradiation System). For the first time, several non-destructive methods (passive gamma-ray spectrometry, high-energy radiography) are combined with traditional PAA techniques (altitude scan, global photofission, photofission tomography) in order to optimize the characterization process.