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Nuclear powerProbability of nuclear reactor core meltdown higher than expected

Published 23 May 2012

Currently, there are 440 nuclear reactors in operation, and sixty more are planned; new research finds that reactor accidents involving a core meltdown, as were the Chernobyl and Fukushima, may occur once every ten to twenty years — some 200 times more often than estimated in the past; the authors of the study note that they did not take into account potential contributing factors to accidents such as the age and type of reactors, or whether reactors are located in regions of enhanced risks such as earthquakes

Catastrophic nuclear accidents such as the core meltdowns in Chernobyl and Fukushima are more likely to happen than previously assumed. Based on the operating hours of all civil nuclear reactors and the number of nuclear meltdowns that have occurred, scientists at the Max Planck Institute for Chemistry in Mainz have calculated that such events may occur once every ten to twenty years (based on the current number of reactors) — some 200 times more often than estimated in the past.

A Max-Planck-Gesellschaft release reports that the researchers also determined that, in the event of such a major accident, half of the radioactive caesium-137 would be spread over an area of more than 1,000 kilometers away from the nuclear reactor. Their results show that Western Europe is likely to be contaminated about once in fifty years by more than forty kilobecquerel of caesium-137 per square meter. According to the International Atomic Energy Agency (IAEA), an area is defined as being contaminated with radiation from this amount onwards.

In view of their findings, the researchers call for an in-depth analysis and reassessment of the risks associated with nuclear power plants.

The reactor accident in Fukushima has fuelled the discussion about nuclear energy and triggered Germany’s exit from their nuclear power program. It appears that the global risk of such a catastrophe is higher than previously thought, a result of a study carried out by a research team led by Jos Lelieveld, director of the Max Planck Institute for Chemistry in Mainz: “After Fukushima, the prospect of such an incident occurring again came into question, and whether we can actually calculate the radioactive fallout using our atmospheric models.” According to the results of the study, a nuclear meltdown in one of the reactors in operation worldwide is likely to occur once in ten to twenty years. Currently, there are 440 nuclear reactors in operation, and sixty more are planned.

To determine the likelihood of a nuclear meltdown, the researchers applied a simple calculation. They divided the operating hours of all civilian nuclear reactors in the world, from the commissioning of the first up to the present, by the number of reactor meltdowns that have actually occurred. The total number of operating hours is 14,500 years, the number of reactor meltdowns comes to four — one in Chernobyl and three in Fukushima. This translates into one major accident, being defined according to the International Nuclear Event

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