This publication describes the characteristics of the electrical grid system that are required for the connection and successful operation of a nuclear power plant, as well as the characteristics of a nuclear power plant that are significant for the design and operation of the electrical grid system. It addresses the issues to be considered when a nuclear power plant is being planned and describes the information exchange necessary between the developer of a nuclear power plant and the organization responsible for the electrical grid. The particular issue of a large nuclear unit connected with a small system is also discussed. A new topic introduced in this publication is the need for cyber security of the grid system near the nuclear power plant. Several case studies of Member States experience in developing new nuclear units and about grid events during operation are included.