Study on Comparison Between Inconel 617 and GH3128 as Structural Material Candidates for Intermediate Heat Exchanger

Intermediate heat exchangers (IHXs) are applied to transfer high-temperature heat generated in high-temperature gas-cooled reactor (HTGR) core to the secondary circulation loop. The requirements for IHXs are harsh due to its high operation temperature up to 900–1000°C, as well as long lifetime expectation. Inconel 617, an austenitic alloy based on nickel-chromium, is considered the primary candidate as IHX structural material for application in NGNP program in USA. This paper compares the characteristics of two nickel-base super alloys, namely GH3128 and Inconel 617, in terms of chemical composition, tensile strength and creep behavior. The result shows that GH3128, which was originally developed and deployed for aeronautic blast chamber in China, is also promising for IHXs in nuclear heat application, but much tests have to be done in the future before its successful application in nuclear high-temperature IHXs.