Experimental and simulated assay of actinides in a real waste package

The non-destructive control of nuclear wastes is important for their management and the non-proliferation. Among the methods using the nuclear radiation as an investigation, the Instrumental Photon Activation Analysis (IPAA) seems to be a promising way to quantify the masses of actinides present in bulky packages of nuclear waste. The IPAA method consists in irradiating actinides with photons of high energy to produce photofission reactions. The counting of the delayed neutrons, produced by these photofission reactions, allows to locate and to quantify the mass of actinides by tomography. At this end, we use a simulation tool named OPERA to obtain the information necessary for the tomographic restitution and an experimental installation based on a LINear ACcelerator (LINAC) to perform the measurements. The high-energy photons (11 MeV) are produced by Bremsstrahlung, thanks to a tungsten target placed in front of the LINAC. In this paper, we present the first experimental results obtained on a real package of nuclear waste. We establish that, for this waste package, the limit of detection, in terms of mass of actinides, is about 1 g. Furthermore, these results show the good agreement between the experiment and the simulation that provides a localization of actinides by tomography.