Production of transmutants and displacement effect in the EURAC spallation neutron source for testing of fusion materials

Two aspects have been criticized when using spallation reactions for fusion material testing: different final damage structures produced by high-energy recoils, and adequacy of the production of gaseous and solid transmutants. Using an original procedure to compute the displacement efficiency it is concluded that no new damage structures can be expected from the high-energy recoils at low temperature. An interaction displacement efficiency representing the interference of subcascades is defined, and it has been found independent of the recoil energy. Computed atomic displacement cascades for recoils of 200 keV and 1 MeV support this conclusion. The rate of He and H production is well compared with fusion, and the contribution from high-energy reactions is remarked. Solid transmutant generation from high-energy spallation neutrons and fusion are compared. A small contribution in the production of important elements is found, the proton flux effect being less significant than that of the neutron flux. (orig.)