Effect of microstructure and neutron irradiation defects on deuterium retention in SiC
Retention of hydrogen isotopes is a critical concern for operating fusion reactors as retained tritium both activates components and removes scarce fuel from the fuel cycle. Radiation-induced displacement damage in SiC may influence the retention of hydrogen isotopes compared to pristine SiC. Deuterium retention in neutron irradiated high purity SiC has been compared to different microstructures of non-irradiated high purity SiC using thermal desorption spectroscopy after gas charging or low energy ion implantation. First principles calculations have been conducted to help interpret results and derive effective diffusivity in the presence of vacancies. Deuterium is released at lower temperatures in neutron irradiated SiC compared to pristine SiC, suggesting weaker trapping by radiation-induced carbon vacancies compared to at grain boundaries in the pristine samples. Low energy ion implanted samples had a high deuterium release temperature suggesting C-H bonding associated with ion irradiation induced displacement damage.