Safety concept of the Swr 1000, an advanced boiling water reactor with passive safety features

The main prerequisite for assuring nuclear safety is a reactor core that is 'inherently safe', i.e. has physical characteristics that will reliably prevent rapid power transients. For new nuclear power plants, the defense-in-depth principle is structured as follows: - Prevention of operational disturbances through high-quality design, manufacture and operation of major plant systems and components; - Provision of limitation and control equipment for preventing operational disturbances from developing into accidents; - Provision of redundant and diverse systems for accident detection and control in order to prevent unallowable damage to the nuclear fuel and unallowable releases of radioactive materials to the environment; - Provision of equipment that, in the postulated event of severe fuel damage, will restrict the consequences of such an event to the plant itself and thus preclude any necessity for large-scale emergency response actions in the vicinity of the plant. Furthermore, the nuclear fuel, components containing high and intermediate activity inventories as well as plant safety systems must be protected against natural and external man-made hazards. As regards the actual production of electricity in a nuclear power plant, the equipment provided for nuclear safety is nothing more than a cost factor. What this means for designers of advanced nuclear power plants is that they must incorporate nuclear safety requirements into their overall plant designs in such a way that safety is increased but costs are reduced. (authors)