For the generation of evaluated nuclear data sets required for the International Fusion Materials Irradiation Facility project, the basic features of the deuteron-lithium and neutron-lithium nuclear interactions are examined. Factors complicating the evaluation of deuteron-lithium reaction characteristics and weak points of previous calculations and evaluations are discussed. A new method to obtain double differential cross sections of particles emitted in d+Li reactions is described. The method is based on the diffraction approach, a modified intranuclear cascade model, and the usual evaluation techniques. The cross sections predicted by this method are in good agreement with existing experimental data for deuteron interactions in thick lithium targets. The study of neutron-lithium interactions is performed on the basis of different approaches: coupled channels, diffraction scattering, and direct breakup models.