High Resolution Neutron Radiography and Tomography of Hydrided Zircaloy-4 Cladding Materials

Hydrogen content and distribution in Zircaloy-4 cladding samples with controlled hydrogen concentrations up to 1100 ppm were studied using neutron radiography and computed tomography. Hydrogen charging was performed in a process tube that was heated to facilitate hydrogen absorption by the metal. A correlation between the hydrogen concentration in the hydrided tubes and the neutron intensity was established, by which hydrogen content can be determined precisely in a small area (55 μm × 55 μm). Image analysis was also performed to evaluate the heating rate and its correlation with the hydrogen distribution through hydrided materials. In addition to image analysis, tomography experiments were performed on Zircaloy-4 tube samples to study the local hydrogen distribution. A 3D reconstruction of the tube was evaluated in which an uneven hydrogen distribution in the circumferential direction can be observed.