As a country advances to Phase 2 of the IAEA Milestones approach in developing its nuclear power programme, the project owner is expected to prepare a comprehensive feasibility study. This study serves to define the project framework, establish a business case for successful implementation, and provide a sound basis for the final investment decision. It also plays an important role in building and maintaining stakeholder support. This publication outlines the typical steps involved in preparing a feasibility study, aligned with the prerequisites of a nuclear power project. The feasibility study development process described is adaptable to various nuclear power project technologies, project designs, sizes, locations and industrial applications, and the specific approach will vary depending on the unique objectives and drivers of each project.