Impact of tritium removal and He-3 recycling on structure damage parameters in a D–D fusion system

Removing tritium produced by D–D fusion and recycling part of it after it decays to He-3 significantly reduces the fraction of fusion energy carried by neutrons in a D–D system. For a catalyzed D–D system (no tritium removal), the peak dpa rate in candidate structural materials is 25–35% lower than that in an equivalent D–T system with the same fusion power wall loading. The gas production and transmutation rates are about 60% lower. As tritium is removed gas production and transmutations decrease by more than two orders of magnitude and the dpa rate decreases by a factor of 2.3–2.8. An additional reduction of a factor of 1.6–1.7 in damage parameters is achieved by recycling the removed tritium as He-3. This results in significant lifetime enhancement of structural materials. Information from tests in fission reactor spectra would be directly relevant in determining the lifetime of the structural material in this He-3-recycled system.