Fission neutron irradiation of copper containing implanted and transmutation produced helium

High purity copper containing approximately 100 appm helium was produced in two ways. In the first, helium was implanted by cyclotron at Harwell at 323 K. In the second method, helium was produced as a transmutation product in 800 MeV proton irradiation at Los Alamos, also at 323 K. The distributions of helium prior to fission neutron irradiation were determined by a combination of transmission electron microscopy (TEM) and positron annihilation techniques (PAT). These specimens, together with pure copper, were then irradiated with fission neutrons in a single capsule in fast flux test facility (FFTF) at approximately 686 +/- 5 K to a dose level of approximately 48 dpa (7.7 X 10(26) nm-2; E > 0.1 MeV). Investigation of the void and dislocation microstructures in the three specimens by TEM showed large differences between the specimens in void size and swelling. The observed differences as well as the effect of the presence of other transmutation produced impurity atoms in the 800 MeV proton irradiated copper will be discussed.