Nuclear fission energy has emerged over the past 40 a to become a reliable source of clean and economical energy.However,an exceptionally harsh environment,which is a big challenges to materials,presents in the core of a nuclear reactor due to the combination of high temperature,high stresses,a chemically aggressive coolant and intense radiation fluxes.Corrosion as the three major materials challenges for the current and next generation of water-cooled fission reactors need be payed more attention to[1].Hence,a facility for studying water vapor corrosion has been developed.