A method for calculating radiation effects parameters as a function of neutron energy is described. The computer code DON is used to generate damage parameters from ENDF/B nuclear data. Both integral data such as neutron spectrum averaged cross-sections and recoil energy spectra are generated. These data were used to characterize initial defect production in Al, Cu, Nb and Au in selected fission reactor, fusion reactor and fusion simulation neutron spectra. The principal differences between fission and fusion damage are the spatial characteristics of defect production and the importance of non-elastic scattering (e.g. He production). The comparison of the damage produced in one spectrum with that produced in another is dependent on the model or parameter chosen to represent the damage. This dependency is important in analyzing simulation spectra for fission and fusion reactor radiation damage problems.