Nondestructive evaluation of solid cargo inside cylindrical containers with linear and nonlinear resonance spectroscopy

Nondestructive evaluation (NDE) of cylindrical containers is of critical importance because of their ubiquity in industrial applications. However, there is a paucity of research on the NDE of solid cargo inside sealed enclosures with external sensors. This talk covers the application of linear and nonlinear resonance spectroscopy to the NDE of cargo inside cylindrical containers. The first study focused on a Transnuclear-32 (TN-32) cask used for the dry storage of spent nuclear fuel assemblies. The modes of the TN-32 were measured onsite and Finite Element Analysis was used to investigate modal changes due to loadings of fuel assemblies. Because of the difficulties introducing damage to fuel assemblies inside a TN-32, a 1:6 scaled cask containing 32 mock-up fuel assemblies was manufactured for laboratory studies. Using the linear approach, metrics were developed that could detect cargo damage down to the single assembly level. To resolve the signatures of damaged versus missing assemblies, nonlinear ultrasound resonance spectroscopy was utilized to investigate the contact nonlinearity between a smaller scale container and loose spheres which mimicked internal debris. Based on the resulting data, a phenomenological contact-loss model was developed which could estimate the total mass of the spheres regardless of the material and radius.