Spallation-neutron-sources, such as those under investigation for use in accelerator-driven transmutation systems, generate neutrons through the collision of high-energy protons, or charged hydrogen atoms, with heavy metal targets such as lead. As a result, these systems also tend to deposit a significant amount of hydrogen in the materials of the transmuter target and superstructure. This can result in accelerated corrosion and changes in the properties of the exposed materials. Of particular importance is a phenomenon called hydrogen embrittlement, in which materials lose their ductility (ability to deform under stress) and become brittle (more susceptible to fracture) after reacting with hydrogen. Given the extreme temperature ranges and large quantities of hydrogen expected in the accelerator-driven transmutation systems, these phenomena are of particular importance to the transmutation program.
This research program will examine the effects of hydrogen on hydrogen embrittlement, environment-induced stress corrosion cracking (SCC), and other hydrogen induced/ enhanced corrosion phenomena in target materials. The UNLV research group will also examine the effectiveness of various surface and heat treatments in minimizing the impact of these phenomena in candidate materials. It is hoped that establishing a baseline performance of these materials in a hydrogen rich environment (analogous to the expected in-proton-beam environment of the target systems) will pave the way for conducting in-proton-beam radiation experiments and eventually support the materials qualification needed for facility design and operation
