Study of structural stability at high temperature of pseudo-single tube with double layer as an alternative method for accident-tolerant fuel cladding

The multilayered swaging and drawing process using raw Zr-alloy cladding is very simple, can be performed at room temperature (15-25 ℃), and enables mass productivity. In this study, we developed a pseudo-single tube with double layers (PSTD), using a thin stainless-steel (SS316L) tube and raw Zr-alloy cladding, which is not easily accessible to a coating process. The PSTD specimens were oxidized at 900 ℃, 1000 ℃, 1100 ℃, and 1200 ℃ for 60 min at each temperature in dry air. The interface between the SS316L tube and Zr-alloy cladding was investigated using optical microscopy and scanning electron microscopy. The oxidation resistance was proven excellent through energy dispersive spectroscopy and mass change results of the oxidized PSTD specimens even though 5-6 µm oxide layer was formed at the interface. Based on these results, it was concluded that an improved accident tolerant fuel (ATF) cladding can be produced using the swaging and drawing process.