Environmental Degradation of Materials in Advanced Reactors

Advanced fission-based reactors challenge our ability to fully understand environment–materials reactions in terms of fundamental stability and kinetics, including the influences of composition, microstructure, and system design, and to predict associated long-term performance. This article briefly describes corrosion reactions and the processes by which such are managed for several elevated-temperature environments associated with advanced reactor concepts: helium, molten Pb–Bi, fluorides, and supercritical water. For most of the subject environments, corrosion resistance critically depends on the ability to form and maintain protective surface layers. Effects of corrosion on mechanical behavior can be from thermally and chemically induced changes in microstructures or from environmental effects on cracking susceptibility. In most cases, the simultaneous effects of chemical reactivity and radiation have not been fully addressed, nor has much attention been paid to newly emerging alloy compositions or the effects of substantially increased operating temperatures.