The effects of Nuclear Elastic Scattering (NES) on the properties of Cat-D and D-3He plasmas are investigated, with special attention given to the discrete nature of NES. A space-independent, linear multi-group method is used for the study. It is found that NES can significantly reduce the nr requirements for plasma ignition; for plasmas characterized by relatively large cyclotron radiation losses, this reduction can exceed 50%. In addition, the treatment of the discrete NES behaviour is shown to be essential for an accurate prediction of the superthermal ion distribution functions.