Design of detachable computed laminography scanning mechanism and neutron tomography detection method for plate-like component

Abstract

Neutron radiography has many advantages over X-ray in inspection of materials containing lighter elements, elements with close atomic numbers, isotopes, radioactive materials and so on, and plays an irreplaceable role in nondestructive testing, material engineering and other fields. However, for plate-like components which are widely used in engineering, traditional neutron computed tomography (CT) scanning, limited by neutron energy, cannot collect complete, high-sensitivity and high-spatial-resolution projection information required for accurate reconstruction, which makes it impossible to obtain ideal reconstruction images of plate-like components. Neutron computed laminography (CL), as a popular nondestructive testing technology, has unique advantages for detection of plate-like components. Aimed at neutron tomographic inspection of plate-like samples, a detachable CL scanning mechanism was designed, and a neutron CL scanning system was built. The FBP (Filtered Back-projection) algorithm, the BPF (Back-projection Filtration) algorithm and the iterative reconstruction algorithm based on the minimization of total variation of 3D reconstructed image were designed. The results showed that FBP algorithm and BPF algorithm are of high reconstruction efficiency and can meet the needs of tomographic imaging in engineering inspection. The iterative reconstruction algorithm based on total variation minimization has advantages of high imaging accuracy and anti-noise, and can effectively suppress the adherent artifacts between adjacent reconstructed slices. Tomographic imaging of typical plate-like components was performed at the China Advanced Research Reactor (CARR) of China Institute of Atomic Energy (CIAE), which verified practicability and correctness of the detachable CL scanning mechanism and the reconstruction algorithms.