Membrane bulge test rig for irradiation-assisted stress-corrosion cracking

During their service in a nuclear power plant, structural materials are subject to high temperature, mechanical stress, corrosive coolant environments, and neutron irradiation. The combination of radiation, corrosion and thermo-mechanical loading represents a unique environment that materials must endure: radiation can significantly alter the material's thermo-mechanical performance and the lifetime of a component. The conditions under which this happens are difficult to study and normally necessitate nuclear reactor experiments followed by post-irradiation examination in hot cells, which renders investigations complex, time consuming and expensive. While few attempts have been made to study the combined effects of radiation and corrosion with lead bismuth eutectic [1] or molten salts [2] none of these experimental set-ups were designed to study the combination of corrosion and irradiation together with mechanical loading. Here the development of a miniature test technique is presented where irradiation, corrosion and strain can synergistically be applied on a material in a controlled way. The experiment is based on scaling down the membrane bulge test [3], using liquid lead as a pressure medium at high temperature. Membrane type specimens are made from the structural material to study, with their back side pressurized thereby inducing corrosion and membrane stretching stress while irradiation damage is generated by proton irradiation at the front surface affecting the entire thickness to the back side of the sample. The paper presents the way how the engineering problems related to the combination of corrosion by liquid metal, stress application and irradiation of the sample have been addressed.