Neutron activation is the process in which neutron radiation induces radioactivity in materials, and occurs when atomic nuclei capture free neutrons, becoming heavier and entering excited states.
Fusion reactors will require so-called “low-activation materials” that aren’t New alloys, called low activation materials have been developed to replace the standard stainless steels with Mn substituting for Ni. Martensitic Cr steels with W added for strengthening appear to have promise.
The primary low activation materials being developed by the international fusion materials community are: (1) Reduced Activation Ferritic-Martensitic (RAFM) steels (2) vanadium alloys; (3) SiC/SiC composites; and (4) Oxide-dispersion-strengthened alloys.
The ARPA-e GAMOW program has funded several projects in this area.