RADIATION EFFECTS IN MATERIALS FOR ACCELERATOR-DRIVEN NEUTRON TECHNOLOGIES

Accelerator-driven neutron technologies include facilities for neutron scattering research, accelerator transmutation of waste (ATW), and ac celerator production of tritium. These systems use spallation neutron sources (SNS's) in which high-energy protons (E=1000-2000 MeV) strike a heavy-metal target, producing spallation neutrons with energies exte nding up to the incident proton energy. The nature of the spallation p rocess and the codes used to calculate spallation radiation damage are reviewed. Calculations of displacement and helium production in a maj or target material, tungsten, are described. Displacement cross sectio ns reach about 9000 b for 1600 MeV neutrons or protons. In a simulated high-current-density ATW SNS, displacement production rates are about 0.1 and 1 dpa/d due to the spallation neutrons and incident 1600 MeV protons, respectively, and the He production rates are about 1 and 250 appm He/d, respectively. These damage rates probably represent an upp er limit to what can be tolerated. More realistic solid-target SNS's w ill operate at lower current densities, and the damage rates are likel y to be reduced by a factor of 3 or 4 from the values cited above. In any case, however, radiation damage to target and container materials is a major consideration in the design of SNS's.