A COMPARISON OF MICROSTRUCTURES IN COPPER IRRADIATED WITH FISSION, FUSION AND SPALLATION NEUTRONS

The microstructures of pure copper irradiated to low doses at 36-90-degrees-C with spallation neutrons, fusion neutrons and fission neutrons are compared. The defect cluster densities for the spallation and fusion neutrons are very similar when compared on the basis of displacement per atom (dpa). In both cases, the density increases in proportion to the square root of the dpa. The difference in defect density between fusion neutrons and fission neutrons corresponds with differences observed in data on the yield stress changes.