PNNL

Abstract

The U.S. Department of Energy, Office of Nuclear Energy Advanced Materials and Manufacturing Technologies Program is developing advanced materials and manufacturing technologies that will enable the safe and economical operation of both the current fleet and the next generation of advanced nuclear reactors. Post-process nondestructive evaluation capabilities are a key enabling technology that will be required to qualify and verify the condition of components produced using advanced materials and manufacturing technologies. In FY23, the three main efforts in post-process nondestructive evaluation were: 1) the use of X-ray computed tomography to characterize microstructural features and defects in powder Direct Energy Deposition (DED) 316L stainless steel material samples, 2) the use of neutron diffraction studies to evaluate the residual stress in the DED 316L fabricated with different process parameters, and 3) the application of resonant ultrasound spectroscopy to measure the elastic properties of Laser Powder Bed Fusion (LPBF) 316H stainless steel material. Each of the methods explored are candidate nondestructive testing approaches for post-process examinations of components fabricated from AM processes. The purpose of this research is to gain a better understanding of the capabilities of these approaches and identify the necessary improvements in processes, procedures and standards to establish their use in qualifying additive manufactured components for safety critical applications. The volumetric examination methods evaluated showed promise in providing detailed information about the material conditions that could be used in failure evaluations of additive manufactured components. The X-ray computer tomography evaluations were able to characterize the amount and type of key hole and lack of fusion porosity in the DED SS 316 L samples. The elastic properties measurements using resonance ultrasound spectroscopy on the LPBF SS316H had good agreement with destructive mechanical testing and was able to assess the differences between wrought SS316L and LPBF SS316H materials. Observations from these activities indicate that further work is needed to standardize volumetric inspection techniques such as X-ray computed tomography, ultrasonic testing, and resonance testing for preservice and inservice inspections as part of a qualified ASME Boiler and Pressure Vessel Code Section XI, Division 2 monitoring and nondestructive examination program for advanced reactors. The near-term future work activities to be pursued include expanding these examinations to larger LPBF and DED components, characterizing a broader range of flaw types and sizes, and expanding.