External hazards. In focus after the Fukushima accident

International experience has shown that external hazards can be safety significant contributors to the risk of industrial plants with a high potential of damage to the environment; this has become evident after the Fukushima accident. As a consequence main focus has been set on adequate design measures against external hazards and appropriate assessment methods. Possible methods to analyse existing plants systematically regarding the adequacy of their existing protection equipment against hazards can be deterministic as well as probabilistic. On international level, new recommendations regarding external hazards are recently issued. In that context, in particular earthquakes and flooding scenarios have been re-evaluated to some extent. Also in Germany, a revised guideline on probabilistic safety analyses (PSA) and corresponding technical documents are issued in 2005 addressing external hazards. As a reaction to the accidents in Japan in March 2011, the German Reactor Safety Commission has issued a catalogue of requirements for plant-specific reviews of German nuclear power plants, and the status of the plants have been evaluated with respect to these requirements. The results of these investigations have been the basis for the German report in the frame of the European stress tests; the results with respect to natural external hazards are presented. (orig.)