PNNL

Abstract

Structural materials of a fusion power system will be exposed to high concentrations of He produced from nuclear transmutation reactions. Helium is essentially insoluble in metals so there is a strong tendency for it to form bubbles that can significantly degrade mechanical properties. A strategy to effectively manage He is to provide a high-density of internal interfaces to serve as He bubble nucleation sites and vacancy-interstitial recombination centers. Nanostructured ferritic alloys are being developed to provide improved creep strength and He management capability compared to conventional steels. A key characteristic of these materials is the high-density (~1024 m-3) of nanometer-scale (~3 nm diameter) Y-Ti-O clusters. We describe molecular dynamics simulations to assess the interaction of He atoms, vacancies and He-vacancy complexes with coherent Cu nanoclusters in Fe. The potentials employed here were adjusted to explore the effect of nanocluster elastic properties on He trapping efficiency.