Spectral Dependence of Activation at Fusion Reactor First Walls

Activation calculations were performed f or 27 elements in the STARFIRE, Mirror Advanced Reactor Study (MARS), and GA Technologies, Inc. (GA) conceptual reactor first-wall neutron spectra. In all the spectra, seven of the elements (nitrogen, aluminum, nickel, molybdenum, copper, niobium, and lead) required restrictions on their concentration in a material in order to meet current regulations for near-surface radioactive waste disposal. For nickel, molybdenum, and niobium in the spectra of MARS and GA, however, the activation levels are two to five times lower than in STARFIRE. Multistep reactions were found to have only a small effect on the limits for these seven elements.