According to the Nuclear Energy Act, the licensee of a nuclear power plant must periodically carry out a comprehensive safety check (Periodic Safety Review, PSR) and, after the fourth decade of operation, provide a safety case for long-term operation. The Nuclear Energy Ordinance specifies the content of the PSR and the safety case for long-term operation.

The aim of the PSR and the long-term operating case is the complete safety assessment of the nuclear power plant. According to the Nuclear Energy Ordinance, such an assessment must be carried out by the licensee at least every 10 years. As part of this, the power plant-specific operating experience of the last ten years must be evaluated and compared with the relevant operating experience of other nuclear power plants. The comprehensive review of the organisation and its management system, as well as the technical and technological ageing processes for safety-relevant components and the results of deterministic and probabilistic safety analyses, taking into account current hazard assumptions, provides important information on the safety of the nuclear power plant and enables forecasts to be made about its future safety status.

The long-term operating case must be used to demonstrate that the future safety status enables safe operation over the planned operating period, that sufficient personnel are available and that safety will be further improved (backfitting concept).