Hazard assessment in case of external flooding

Risks relating to external hazards, either natural or man-made, have to be taken into consideration in the design of nuclear and other industrial facilities. These risks have to be studied to guarantee the availability and efficiency of safety functions which, e.g. in the case of power reactors, enable a safe shutdown, maintain the reactor in a safe shutdown state, ensure the residual heat removal and the containment of radioactive products. With a view to design protection against risks related to external hazards, these hazards have to be assessed in an appropriate manner. The methods used can be either deterministic or probabilistic. In both cases, the method strongly relies on observations (e.g. flood records) that are processed to define a maximum event for the respective facility design. Moreover, the validity of these records over a certain time frame like 100 years has to be checked. Coping with external hazards such as flooding in the future requires an in-depth assessment taking into account new data, further developed methodologies and criteria. Some of these ideas, developments and applications are provided.