Transient oxidation of Zircaloy fuel cladding in high temperature steam

Reactor grade Zircaloy-4 specimens were subjected to a temperature transient of different heating rates as well as to isothermal heating in flowing steam. Both electrical internal heating and external heating by infrared radiation were used. Following each test the oxide layer and the stabilized α-layer thicknesses, using metallographic examination, were obtained as a measure of corrosion rates. The measured oxide thickness above heating rates of 30C/s are found to deviate from the parabolic rate law by this experimental study. The comparison between fitted parameters from earlier studies will be discussed for both transient and isothermal measurements. (orig.)