Deterministic safety analysis is an essential component of safety assessment, particularly for safety demonstration of the design of nuclear power plants (NPPs). The objective of deterministic safety analysis is to confirm that safety functions can be fulfilled and that the necessary structures, systems and components, in combination with operator actions, are effective in keeping the releases of radioactive material from the plant below acceptable limits. Deterministic safety analysis, supplemented by further specific information and analysis, including probabilistic safety analysis, is also intended to demonstrate that the source term and the potential radiological consequences of different plant states are acceptable, and that the possibility of certain conditions arising that could lead to an early or a large radioactive release can be considered as ‘practically eliminated’. The publication has been updated to maintain consistency with current IAEA safety requirements and to reflect lessons from the Fukushima Daiichi accident. It takes into account current practices and experience from deterministic safety analyses for NPPs being performed around the world.