The International Reporting System for Operating Experience (IRS) is an essential element of the international operating experience feedback system for nuclear power plants. Its fundamental objective is to contribute to improving safety of commercial nuclear power plants which are operated worldwide. IRS reports contain information on events of safety significance with important lessons learned which assist in reducing recurrence of events at other plants. This sixth publication, covering the period 2012 - 2014, follows the structure of the previous editions. It highlights important lessons based on a review of the approximately 240 event reports received from the participating countries over this period.

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.