Supplemental Material

The Supplemental Material PDF contains two major sections. The first section provides further details on the training, validation, and calculated properties of the helium interatomic potentials used in this work. The second section provides additional helium property data not directly relevant for the main manuscript, including atomic volume distributions from undamaged bulk CCA cells, formation energies and migration barriers for enriched/depleted Ta and Ti CCA compositions, and the formation energies and migration barriers of helium in tetrahedral interstitial sites.