Material Qualification for Molten Chloride Fast Reactor Applications – Testing Needs and Knowledge Gaps

Molten chloride fast reactors are one of the many advanced reactor technologies currently under development in the United States and abroad. They are characterized by their liquid fuel (chloride fuel salt), fast neutron spectrum, and high-temperature low pressure operation. These characteristics provide operational advantages, e.g. fuel efficiency, while at the same time pose challenges, specifically concerning material degradation. There are strict requirements imposed on materials used in safety-related/safety significant applications in high-temperature commercial nuclear power reactors, including both physical/mechanical properties and environmental compatibility. Moreover, due to the lack of operational experience with molten chloride salts, the current understanding of degradation phenomena is limited. It is generally accepted that the primary mode for salt-material interaction is through the selective leaching of metallic alloying elements such as chromium. However, little work exists on additional environmentally assisted degradation and cracking mechanisms that may occur in a molten chloride salt environment and, moreover, the facilities capable of performing such testing are limited. This contribution will present the existing knowledge/data gaps from a material selection and qualification perspective and discuss the current landscape of testing facilities. Additionally, the current and future testing needs, from a developer perspective, will be shared.