Post Irradiation Examination of a Thermo-Mechanically Improved Version of EUROFER ODS

EUROFER is a 9Cr-1W-0.2V-0.1Ta reduced activation ferritic/martensitic (RAFM) steel, presently considered within the European Union as the primary candidate structural material in a fusion power plant. Its mechanical strength properties currently prevent its use at temperatures higher than 500-550 degrees Celsius. In an effort to extend the range of operating temperatures to 600-650 degrees Celsius and therefore enhance the efficiency of the machine, a different production route, Oxide Dispersion Strengthening (ODS), is being investigated. The characteristics of different versions of EUROFER ODS have been assessed in recent years, leading to the improvement of the material by a combination of optimized production process and post-thermal treatment. Until recently, the mechanical properties of EUROFER ODS had only been investigated in the unirradiated condition, and no information was available for the irradiation response of the material. However, mechanical samples have been irradiated during 2004-2005 at 300 degrees Celsius in the Belgian Reactor 2 (BR2) in Mol to an accumulated dose of 1.73 dpa; tensile, Charpy impact and fracture toughness tests have been performed in the hot cell laboratories of the Belgian Nuclear Centre (SCK-CEN). Metallographic and microstructural investigations were also performed on the investigated material in both the unirradiated and irradiated condition.