Abstract
Dry storage canisters are used to hold the nuclear spent fuel for an interim period before transporting to the final disposal site. Austenitic 304 stainless steels and carbon steels are widely used as structural materials for nuclear power plants owing to its mechanical and corrosion resistance properties. The present study involved the investigation of photoelectrochemical behavior of TiO2 coated carbon steel as a structural material for dry storage canister aiming to prolong the photocathodic protection of carbon steel over a period of time after the shutdown off the UV illumination. The crystallinity of TiO2 coating was analyzed with the aid of Grazing Incident X-ray Diffraction (GIXRD) and the thickness of the oxide layer were analyzed with Scanning Electron Microscopy (SEM). The interfacial oxide layer was investigated with Laser Raman Spectroscopy to determine the residual magnetite and hematite phases. Electrochemical polarization analyses and open circuit potential measurements were conducted to evaluate the corrosion mitigation efficiency of the TiO2 coated carbon steel under UV illumination and dark condition. The results revealed that under appropriate heat treatment condition, the intermediate iron oxide layer formed not only deterred the diffusion of Fe from the substrate but also enhanced the photocatalytic effect of TiO2 coating. The addition of Fe dopant (Fe:Ti 1:1) helped to improve the slow rise of potential under the paucity of UV illumination. The results indicated that the plain TiO2 and doped TiO2 coating in combination with UV illumination mitigate the corrosion rate of the carbon steel in both dark and UV illumination conditions.