Helium and hydrogen release measurements on various alloys irradiated in SINQ

Three irradiations have been performed in the Swiss Spallation Neutron Source (SINQ) to establish a materials database for mixed proton and neutron fluxes for future spallation neutron and other accelerator sources. Samples of 316LN, F82H, AlMg3, and Zircaloy-2 from STIP-II have been analyzed for their total helium and hydrogen contents and their release characteristics with temperature. Helium and hydrogen release measurements showed considerable levels of deuterium and tritium species which generally mirrored those of hydrogen. Hydrogen release occurred from about 300 °C for the AlMg3 to about 800 °C for the Zircaloy-2. For the Zircaloy-2 and the steels, helium release began to occur at between 1100 and 1200 °C, which is consistent with previous measurements on irradiated steels. Modeling of the hydrogen release data for the 316 and F82H suggests two traps of differing energy dependent on the irradiation dose and temperature. The higher energy traps are probably voids created from vacancy coalescence.