2017 | AFC ACCOMPLISHMENTS 104 Transmutations fuels consist of a combination of high Z (U, Pu) atoms that are also strong absorbers for thermal neutrons (239 Pu).Tomographic methods based on X-rays or thermal neutrons are therefore not suitable to characterize the bulk (mm-cm) of these materials. However, utilizing the ability to pick certain neutron energies in time-of- flight imaging at which the neutron cross-section of the isotopes contained in the samples is low, these sample can be penetrated and characterized by tomographic methods. Using areal density analysis of the isotopes in the beam path of the transmission signal from each pixel, 2D areal densities and ultimately 3D gravimetric densi- ties can be also derived from the same measurement.This was demonstrated at Los Alamos National Laboratory (LANL) on two U-20Pu-10Zr samples with and without Am/Np produced at Idaho National Laboratory (INL). Project Description: Characterization methods applicable to the bulk, i.e. cm sized volumes, of nuclear fuels, are sparse. Neutron CT provides characterizations of dimensions and macrostructural features such as voids and cracks. However, for enriched fuels or fuels containing strong neutron absorbers, such as 239 Pu, thermal neutrons do not work as even layers of