Considerations of alloy 617 application in the Gen IV nuclear reactor systems - Part II: Metallurgical property challenges

Alloy 617 is currently considered as a leading candidate material for high temperature components in the Gen IV Nuclear Reactor Systems. Because of the unprecedented severe working conditions beyond its commercial service experience required by the Gen IV systems, the alloy faces various challenges in both mechanical and metallurgical properties. Following a previous paper discussing the mechanical property challenges, this paper is focused on the challenges and issues in metallurgical properties of the alloy for the intended nuclear application. Considerations are given in details about its metallurgical stability and aging evolution, aging effects on mechanical properties, potential Co hazard, and internal oxidation. Some research and development activities are suggested with discussions on viability to satisfy the Gen IV Nuclear Reactor System needs.