Hydrogen and Helium Production Cross Sections for 15-MeV Neutrons on Types 316 and 304 Stainless Steel

Hydrogen and helium production cross sections have been measured for 15-MeV neutrons incident on Types 316 and 304 stainless steel. A charged-particle magnetic-quadrupole spectrometer was used to measure the (n, xp), (n, xd), and (n, xα) cross sections and the charged-particle spectra. The measured gas production cross sections, 260 ± 38 mb for hydrogen and 48 ± 7 mb for helium, differ by as much as 73% from those used in previous assessments of candidate materials for fusion reactors. The energy spectrum of recoil nuclei from (n, xα) reactions, deduced here directly from the alpha-particle spectra, also differs from calculated spectra used in predicting displacement damage.