Reduction in the onset time of breakaway oxidation on Zircaloy cladding ruptured under simulated LOCA conditions

The cause of the reduction in the onset time of breakaway oxidation was investigated with changing possible influential parameters. The onset time of breakaway oxidation was reduced only in the case where thick and porous oxide was formed on the inner surface of the cladding after rupture. Results of the parametric experiments suggest that the tensile stress in the circumferential direction generated by the thick oxide film formed on the inner surface is a main cause of the reduction in the onset time of breakaway oxidation.