New developments in fusion materials research using surrogate neutron spectra

The use of surrogate irradiation facilities to conduct fusion-relevant materials research requires that fission-fusion correlations be developed to account for the difference between the surrogate and fusion spectra. It is shown that with the exception of 59Ni isotopic doping of nickel-containing alloys and irradiation in a temperature-controlled environment it is almost impossible to study the effects of helium without introducing other important variables such as displacement rate, temperature history and solid transmutants. When helium effects are studied in the absence of differences in these variables, helium's impact on macroscopic properties is shown to sometimes be second order in magnitude. Differences in displacement rate and temperature history can comletely dominate experiments directed toward the study of PKA recoil spectra and helium/dpa ratio. (orig.)