This publication presents the basic concepts and techniques for conducting economic evaluations of nuclear energy system alternatives. It supplements the publications on the INPRO Methodology in the area of economics and on the INPRO service analysis support for enhanced nuclear energy sustainability (ASENES). The economic concepts presented in the report are generic but central to the economic evaluation of alternative nuclear energy projects. The report also highlights the essential aspects beyond the scope of an INPRO nuclear energy system assessment in the area of economics, such as system effects, environmental and external costs, and macroeconomic impacts. These aspects are to be included in a realistic economic comparison of nuclear energy systems and potential alternatives. The report also explains the limits in applying the presented economic evaluation approaches.