[en] This report gives an overview of the regulatory concepts and practices for the periodic safety review of nuclear power plants in OECD countries with nuclear power programmes. The statutory bases for such reviews, their objectives and the processes adopted are summarised against the background of each country's regulatory practices. Although periodic safety reviews are now, or will soon be, part of the regulatory process in the majority of countries, the national approaches to these reviews still differ considerably. This report includes numerous examples of the different concepts and practices in OECD countries, thereby illustrating the variety of ways adopted to reach the common goal of maintaining and improving nuclear safety