Fluoride Salt-Cooled High-Temperature Reactors (FHRs) are a promising new class of thermal-spectrum nuclear reactors. The reactor structural materials must possess high-temperature strength and chemical compatibility with the liquid fluoride salt as well as with a power cycle fluid such as supercritical water while remaining resistant to residual air within the containment. Alloy N was developed for use with liquid fluoride salts and it possesses adequate strength and chemical compatibility up to about 700°C. A distinctive property of FHRs is that their maximum allowable coolant temperature is restricted by their structural alloy maximum service temperature. As the reactor thermal efficiency directly increases with the maximum coolant temperature, higher temperature resistant alloys are strongly desired. This paper reviews the current status of Alloy N and its relevance to FHRs including its design principles, development history, high temperature strength, environmental resistance, metallurgical stability, component manufacturability, ASME codification status, and reactor service requirements. The review will identify issues and provide guidance for improving the alloy properties or implementing engineering solutions.
- Pressure Vessels and Piping Division
Considerations of Alloy N for Fluoride Salt-Cooled High-Temperature Reactor Applications
Ren, W, Muralidharan, G, Wilson, DF, & Holcomb, DE. "Considerations of Alloy N for Fluoride Salt-Cooled High-Temperature Reactor Applications." Proceedings of the ASME 2011 Pressure Vessels and Piping Conference. Volume 6: Materials and Fabrication, Parts A and B. Baltimore, Maryland, USA. July 17–21, 2011. pp. 725-736. ASME. https://doi.org/10.1115/PVP2011-57029
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