In order to investigate the impact of nuclear energy introduction in a country with a fossil fuel based energy mix, several scenarios have been compared in terms of fuel cycle needs (resources and infrastructure) and wastes produced.

As case study, the Italian situation (represented by ca. 300 TWhe-y of electricity needs in 2007 and by no nuclear energy production at present) has been selected. However, the obtained results could be extrapolated to other countries by means of scale factors.

For the reference scenario, the introduction of Gen.III+ Light Water Reactors and once-through fuel cycle has been considered. Under the hypothesis that only the plutonium produced in the country will be available and used for a possible transition to a fast fleet, the introduction of different types of fast reactors (a 600 MWe lead-cooled and two 1500 MWe sodium-cooled systems with different breeding characteristics) and of a more sustainable fuel cycle (closed or partially closed) have been compared. The adoption of fast systems enables to reduce of 50% the uranium consumption and to favorably impact the cycle back-end by reducing the Pu inventory in the cycle, and by reducing the long term waste radiotoxicity and heat load in a repository.

A parametric study has been carried out in order to deal with the systematic uncertainties connected to scenario investigations.