Corrosion test of Cr- and Al-containing alloys in static LBE at 550 deg. C

Lead-Bismuth Eutectic (LBE) is a very attractive coolant of fast reactors for their low melting temperature, high boiling temperature, chemical stability and neutron transparency. In addition, LBE itself is a very efficient spallation target for neutron generation via a high-energy proton accelerator. Earlier lead or LBE-cooled nuclear energy systems, however, have suffered from their high corrosiveness for conventional structural metals. Typical system lifetime goal for those advanced liquid metal cooled nuclear power systems exceeds 60 years in order to compete with ALWR s in economy and reliability. In this study, isothermal corrosion experiments of ferritic/martensitic steels (HT9, EP823) and austenitic steel (SS316L) as well as Al-containing alloys(PM2000, MA956, Kanthal APM, Kanthal AF) have been conducted in static LBE at 550 deg. c. After testing, the thickness and compositional profile of the oxide layer were analyzed by SEM and EPMA in order to compare the protective capability. The formation of thin and stable aluminum oxide layer which is effective as a barrier against the dissolution attack of LBE at the surface of Al-containing alloys. It is found that small amount of yttrium containing FeCrAl alloy (Kanthal AF) showed best compatibility with LBE due to formation of a thin and stable protection layer on the surface. (authors)