High Fidelity CT Imaging of High-Z Materials for Rocket Motor Aging Detection

Propellant aging in solid rocket motors can result in various defects such as micro-cracks, fissuring, and abnormal density variations. These defects can lead to abnormal burn rates and unsafe operations of the motor. Nondestructive inspection of solid rocket motors is critical in monitoring aging of solid rocket motors. High energy gamma-ray CT is a nondestructive inspection method to evaluate structural integrity of a rocket motor. Various artifacts in the reconstructed image due to sampling, beam geometry, and high-Z beam hardening and scattering in the rocket motor can hinder the ability to detect defects and subtle changes over time due to aging. High fidelity Monte Carlo simulation of gamma-ray interaction and transport through solid rocket motors is proposed to characterize such artifacts. New high-Z beam hardening and scatter mitigation algorithms will be derived from the simulation and applied to projected CT data. Novel reconstruction algorithms beyond standard back projection will be used to reprocess the CT data for image reconstruction. The fidelity of high resolution image reconstruction of aging effects after high-Z artifact mitigation will be verified with full Monte Carlo simulation.