The development and implementation of an appropriate infrastructure to support the successful introduction of nuclear power and its safe, secure, peaceful and efficient application is an issue of central concern, especially for countries that are considering and planning their first nuclear power plant. In preparing the necessary nuclear infrastructure there are several activities that need to be completed. These activities can be split into three progressive phases of development. In order to assist with the best use of resources, a description of the conditions which would be expected to be achieved by the end of each phase is provided. The term "milestones" refers to the conditions necessary to demonstrate that the phase has been successfully completed. This publication can be used by Member States to assess their own development status and to prioritize the activities that they need to complete in order to prepare to order, license, construct and then operate a nuclear power plant.