Through its SEED service, the IAEA assists its Member States with their selection for nuclear power plant sites. SEED, which stands for Site and External Event Design, is operated by the Agency's International Seismic Safety Centre (ISSC). One of the main considerations when selecting a site is the assessment of external hazards. Sujit Samaddar, Head of the ISSC, explains what these hazards are and discusses the support offered by the Centre.