Frequency of occurrence and causes: In the year 2015 there exist approximately 440 nuclear power plants (NPPs) in 28 countries, often in areas of high population density. After the NPP accidents of Three Mile Island (USA, 1979), Chernobyl (1986) and Fukushima (Japan, 2011) nuclear disasters unfortunately can no longer be considered hypothetical or unlikely. Among the diversity of the causes of accidents, technical malfunctions, human error, aging facilities, fire risk, exceptional climatic events, terrorism and plane crashes have to be mentioned.
Magnitude, complexity and nuclear fallout: Nuclear disasters are not comparable to other types of natural or technological disasters because of their magnitude and complexity and the high risk of regional and global radioactive contamination by a large diversity of released radio-enuclides, which are invisible, odorless and frequently long lasting.
Management: managing nuclear disasters is very complicated as emergency measures are extremely difficult, due to possibly high radiation levels of the site of the accident. Furthermore, the geographical and meteorological situations may influence salvage measures. Long term management may require costly wide-spread decontamination and storage of large amounts of high level radio-active waste.
Immediate and long-term health effects: Due to ionizing radiation nuclear disasters may have serious immediate effects on the health of the salvage teams. Due to their limited operating times in a high radiation environment, recruitment of large numbers of liquidators must be anticipated. Besides short-term health effects, environmental contamination may have serious long-term consequences for the health of the po- pulation and animals living in the vicinity of the NPPs. In particular pregnant women and small children may sustain genetic damage, which could be expressed only years after exposure. Other long-term effects are different neoplastic and non-neoplastic diseases.