This work focuses on the definition of a suitable methodology to compare different nuclear energy options, with particular attention to strategies able to minimize nuclear wastes. In order to set possible transition scenarios from actual GEN-II reactors, the energy demand and the nuclear energy share up to 2050 have been evaluated by means of data available in the international literature. To compare the different options, major indicators of energy-electricity sector have been analyzed. With particular attention to nuclear energy social acceptability the major indicators investigated are the inventory and the radiotoxicity vs. time of residual wastes. In order to reach a final equilibrium situation, transition scenarios, where GEN-III (e.g. EPR) and GEN-IV new reactors (as lead cooled fast ones), have been analyzed. As cases study Spain and France scenarios have been considered.