Information from the Evaluated Nuclear Data File (ENDF/B) has been used to construct energy-exchange kernels describing the energy transfer probabilities between neutrons and material lattice atoms. The kernels correctly incorporate all the available information on elastic scattering and inelastic scattering contained in ENDF/B. Their use removes much of the uncertainty in the calculation of primary-recoil spectra. Primary-recoil atom spectra for several elements in different reactor spectra have been generated. The influence of inelastic scattering on the recoil spectra is discussed. Results obtained with the ENDF/B data are compared with previously published information.