Passive safety systems in view of sustainable development

The international community starts the development of new advanced reactor design by including the use of passive safety systems. In this framework it is considered the use of the natural circulation for the cooling of the core in normal and transient conditions. Taking into account the advantages and disadvantages of the natural circulation, a compromise between active and passive systems has to be considered in the design of a new reactor to improve the safety and public acceptability of a nuclear power plant. In this paper is presented a brief description of some passive safety systems based on natural circulation and some design, of advanced reactors, using natural circulation for removing the core power in normal operation.