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(FT/1-1Rb) On the Potentiality of Using Ferritic/Martensitic Steels as Structural Materials for Fusion Reactors

N. L. Baluc1)
1) Centre of Research in Plasma Physics, Swiss Federal Institute of Technology - Lausanne, Association EURATOM - Swiss Confederation, Villigen-PSI, Switzerland

Abstract.  Reduced activation ferritic/martensitic (RAFM) steels are the reference as structural materials for the future fusion reactors. They have proven to be a good alternative to austenitic steels for their higher swelling resistance. However, RAFM steels exhibit an irradiation-induced low temperature hardening and an increase in the ductile-to-brittle transition temperature, which imposes a severe restriction on their reactor applications at temperatures below 300 C. Furthermore, a high density of small helium bubbles has been recently evidenced in specimens that were proton-irradiated at about 300 C to a dose of 10 dpa, which could affect their fracture mechanical behavior at intermediate temperatures. Their temperature window of use is presently limited by a drop in mechanical strength at about 600 C. So, new variants that can better resist at high temperatures, are currently being developed, mainly using a stable oxide dispersion. The potentiality of using present RAFM steels and the variants being developed for the first wall of future fusion reactors will be reviewed and compared to that presented by other materials.

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IAEA 2003