Oxidation behaviour of EUROFER-97 under simulated water-cooled lithium lead breeder blanket conditions

The effect of water chemistry, surface condition, alkalizing agent (LiOH vs. KOH), and Zn addition was investigated at 300 °C on the oxidation behaviour of reduced activation ferritic martensitic (RAF/M) EUROFER-97. EUROFER-97 is the proposed material for the water-cooled lithium lead breeder blanket (WCLL-BB) section of DEMO, but its behaviour under elevated temperature hydrogenated water has never been investigated. Advanced material characterization showed that, despite its relatively low chromium content, EUROFER-97 exhibits high corrosion resistance. This is because EUROFER-97 is protected by an inner polycrystalline FeCr₂O₄ layer, formed regardless of the water chemistry and surface preparation investigated. The outer non-protective oxide consists of Fe₃O₄ crystallites, which were refined when KOH was used. When injected, Zn was observed only on top of the outer crystallites without diffusing into the inner oxide layer. These findings demonstrate the excellent oxidation behaviour of EUROFER-97 in the proposed water chemistry, highlighting its suitability for the WCLL-BB section.