Calculated Atom Displacement and Gas Production Rates of Materials Using a Fusion Reactor First Wall Neutron Spectrum

Abstract

The displacement per atom and gas production rates have been calculated for a number of alloys and elements using a design neutron spectrum at the first wall of a fusion reactor. These rates can be combined for most alloys to yield the defect production rates, the parameters currently used to extrapolate available irradiation effects data to fusion reactor conditions. Calculated rates of atom displacement and hydrogen generation in stainless steels are relatively insensitive to recent changes in the nuclear data files and to neutron spectrum differences produced by slight reactor design changes. In contrast, the helium production rate is sensitive to these changes and to the exact alloy composition. Composition variation within the specification range for Type 316 stainless steel can produce variations of ±9% in the helium generation rate.