A review on current status of alloys 617 and 230 for gen IV nuclear reactor internals and heat exchangers

Alloys 617 and 230 are currently identified as two leading candidate metallic materials in the down selection for applications at temperatures above 760°C in the Gen IV nuclear reactor systems. Qualifying the materials requires significant information related to codification, mechanical behavior modeling, metallurgical stability, environmental resistance, and many other aspects. In the present paper, material requirements for the Gen IV nuclear reactor systems are discussed; available information regarding the two alloys for the intended applications are reviewed and analyzed; and further R&D activities are suggested. In the United States the major requirement for qualifying the materials is to satisfy the ASME Subsection NH, with adequate considerations for NRC, ASME NQA-1, and Section XI. In comparison, Alloy 617 is more studied with larger existing databases in air and helium, while Alloy 230 may have highly desired potentials but needs more exploration. To provide a sound technical basis for the material selection decision, more data should be generated to characterize behaviors of both alloys in creep, loading rate sensitivity, fatigue, creep-fatigue, crack resistance, toughness, product form dependency, and metallurgical stability.