This report discusses the means and principal issues for the development of a nuclear economic performance international system, with the purpose of enhancing nuclear power plant competitiveness. It addresses the major transformations occurring in the electricity generation industry to achieve operation and maintenance (O&M) cost reductions and is therefore primarily intended for nuclear power plant and utility managers. The report further presents the preliminary results of a pilot project showing a collection of cost data on a few nuclear power plants, which was used to verify the adequacy of the definitions and terminology set. Contents: 1. Introduction; 2. Transformations causing utilities to optimize O&M costs; 3. Applicability of a nuclear economic performance international system; 4. Establishing a nuclear economic performance international system (NEPIS); 5. Conclusions; Annex I: Using frontier analysis to optimize costs and performance; Annex II: Monetary conversion tables; Annex III: Definitions and terminology for NEPIS; Annex IV: Glossary of business terms; Annex V: IAEA power reactor information system definitions.