This document applies to nuclear power plants with water cooled reactors and, in particular, to the design of components and civil structures against seismic events in order to meet the safety objectives. For other nuclear facilities the applicability of the document is checked in advance, before it might be applied correspondingly. Seismic isolation is not adressed in the series of ISO 4917. The following safety objectives are defined in order to ensure the protection of people and the environment against radiation risks: a) controlling reactivity; b) cooling fuel assemblies; c) confining radioactive substances; d) limiting radiation exposure.