Nuclear material identification using resonant ultrasound spectroscopy

Abstract

Resonant ultrasound spectroscopy (RUS) is a well-established method for determination of the full tensor of elastic moduli of a solid sample in a single frequency sweep. The elastic moduli, together with density, can provide information related to materials fabrication processes, providing a unique signature, or fingerprint, of a material. The goal of this study was to provide forensics for nuclear materials in solid ceramic or metallic form, including composition. The premise of this study was that it is really difficult to find two materials whose density and shear and /or bulk modulus match. We used RUS to determine the bulk and shear modulus for a total of 27 samples. The samples consisted of depleted uranium oxide (MOX) with different doping of Ce, Pu, and Nd oxides, and different methods of fabrication. They were in form of cylinders with flat and parallel faces. Two-dimensional and three-dimensional spaces were investigated, using shear modulus, bulk modulus, and density as variables. The densities varied between 9.0 and 10.6 g/cc, while the shear modulus was 55–80 GPa, with a bulk modulus of 150–240 GPa. The results obtained suggest that there is a good correlation between the elastic moduli and density for samples of different compositions/origins.