Low-activation properties of novel Cr-based materials for fusion reactors

Due to the low neutron-induced radioactivity of their main constituent, two novel Cr-based structural materials are examined, from the low-activation properties viewpoint, as candidate first-wall materials for fusion reactors. The two alloys are Cr-5Fe-1Y2O3, and Cr-44Fe-5Al-0.3Ti-0.5Y2O3. Their low-activation properties have been compared with those of some reference materials, in particular the austenitic steel AISI 316L, the Mn-based reduced-activation steel OPTSTAB, a V-5Ti alloy and a ceramic matrix composite (SiC/SiC). Impurities and tramp elements have been included in the calculations. Irradiation conditions envisaged for the SEAFP (Safety and Environmental Assessment of Fusion Power) study have been adopted. Advantages of the proposed materials with respect to steels, either reference alloys or reduced-activation ones, appear evident from the results of the activation analysis. Cr-5Fe-1Y2O3, in particular, shows excellent low-activation characteristics. This material can be a good choice for further development and characterization of first-wall and blanket structural materials for fusion power reactors. (orig.)