Corrosion degradation of AISI type 304L stainless steel for application in nuclear reprocessing plant

The degradation of materials involving corrosion in handling nitric acid in the spent fuel nuclear reprocessing plant is a serious issue. In the present work, the corrosion resistance of American Iron and Steel Institute (AISI) type 304L stainless steel (SS) and nitric acid grade (NAG) type 310L SS in 1 to 11.5 M HNO3 and boiling 15.65 M HNO3 was evaluated. In both the alloy steels, the open circuit potential and corrosion potential are shifted to more noble potential with increasing concentrations. However, the passive current density was not affected, and the transpassive potential was shifted to higher potential with increasing concentrations. The corrosion rate measured in boiling 15.65 M HNO3 after 240 h shows a much lower corrosion rate in type 310L SS (similar to 0.06 +/- A 0.012 mm/y) then type 304L SS (similar to 0.18 +/- A 0.02-0.2 +/- A 0.001 mm/y). These observations are corroborated with the scanning electron microscope (SEM) morphologies that show severe intergranular corrosion (IGC) attack in type 304L SS then in type 310L SS. The X-ray photoelectron spectroscopy (XPS) study of the passive oxide films of both alloy steels shows the presence of Cr2O3 and SiO2, and the depth profile indicated predominant Si enrichment.