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Catastrophic nuclear accidents such as the core meltdowns inChernobyl and Fukushima are more likely to happen than previouslyassumed. Based on the operating hours of all civil nuclear reactorsand the number of nuclear meltdowns that have occurred, scientistsat the Max Planck Institute for Chemistry in Mainz have calculatedthat such events may occur once every 10 to 20 years (based on thecurrent number of reactors) -- some 200 times more often thanestimated in the past. The researchers also determined that, in theevent of such a major accident, half of the radioactive caesium-137would be spread over an area of more than 1,000 kilometres awayfrom the nuclear reactor. Their results show that Western Europe islikely to be contaminated about once in 50 years by more than 40kilobecquerel of caesium-137 per square meter. According to theInternational Atomic Energy Agency, an area is defined as beingcontaminated with radiation from this amount onwards. In view oftheir findings, the researchers call for an in-depth analysis andreassessment of the risks associated with nuclear power plants. The reactor accident in Fukushima has fuelled the discussion aboutnuclear energy and triggered Germany's exit from their nuclearpower program. It appears that the global risk of such acatastrophe is higher than previously thought, a result of a studycarried out by a research team led by Jos Lelieveld, Director ofthe Max Planck Institute for Chemistry in Mainz: "AfterFukushima, the prospect of such an incident occurring again cameinto question, and whether we can actually calculate theradioactive fallout using our atmospheric models." Accordingto the results of the study, a nuclear meltdown in one of thereactors in operation worldwide is likely to occur once in 10 to 20years. Currently, there are 440 nuclear reactors in operation, and60 more are planned. To determine the likelihood of a nuclear meltdown, the researchersapplied a simple calculation. They divided the operating hours ofall civilian nuclear reactors in the world, from the commissioningof the first up to the present, by the number of reactor meltdownsthat have actually occurred. The total number of operating hours is14,500 years, the number of reactor meltdowns comes to four -- onein Chernobyl and three in Fukushima. This translates into one majoraccident, being defined according to the International NuclearEvent Scale (INES), every 3,625 years. Even if this result isconservatively rounded to one major accident every 5,000 reactoryears, the risk is 200 times higher than the estimate forcatastrophic, non-contained core meltdowns made by the U.S. NuclearRegulatory Commission in 1990. The Mainz researchers did notdistinguish ages and types of reactors, or whether they are locatedin regions of enhanced risks, for example by earthquakes. Afterall, nobody had anticipated the reactor catastrophe in Japan. 25 percent of the radioactive particles are transported furtherthan 2,000 kilometres Subsequently, the researchers determined the geographicdistribution of radioactive gases and particles around a possibleaccident site using a computer model that describes Earth'satmosphere. The model calculates meteorological conditions andflows, and also accounts for chemical reactions in the atmosphere.The model can compute the global distribution of trace gases, forexample, and can also simulate the spreading of radioactive gasesand particles. To approximate the radioactive contamination, theresearchers calculated how the particles of radioactive caesium-137( 137 Cs) disperse in the atmosphere, where they deposit on Earth'ssurface and in what quantities. The 137 Cs isotope is a product of the nuclear fission of uranium. It has ahalf-life of 30 years and was one of the key elements in theradioactive contamination following the disasters of Chernobyl andFukushima. The computer simulations revealed that, on average, only eightpercent of the 137 Cs particles are expected to deposit within an area of 50kilometres around the nuclear accident site. Around 50 percent ofthe particles would be deposited outside a radius of 1,000kilometres, and around 25 percent would spread even further than2,000 kilometres. These results underscore that reactor accidentsare likely to cause radioactive contamination well beyond nationalborders. The results of the dispersion calculations were combined with thelikelihood of a nuclear meltdown and the actual density of reactorsworldwide to calculate the current risk of radioactivecontamination around the world. According to the InternationalAtomic Energy Agency (IAEA), an area with more than 40kilobecquerels of radioactivity per square meter is defined ascontaminated. The team in Mainz found that in Western Europe, where the densityof reactors is particularly high, the contamination by more than 40kilobecquerels per square meter is expected to occur once in aboutevery 50 years. It appears that citizens in the densely populatedsouthwestern part of Germany run the worldwide highest risk ofradioactive contamination, associated with the numerous nuclearpower plants situated near the borders between France, Belgium andGermany, and the dominant westerly wind direction. If a single nuclear meltdown were to occur in Western Europe,around 28 million people on average would be affected bycontamination of more than 40 kilobecquerels per square meter. Thisfigure is even higher in southern Asia, due to the densepopulations. A major nuclear accident there would affect around 34million people, while in the eastern USA and in East Asia thiswould be 14 to 21 million people. "Germany's exit from the nuclear energy program will reducethe national risk of radioactive contamination. However, an evenstronger reduction would result if Germany's neighbours were toswitch off their reactors," says Jos Lelieveld. "Not onlydo we need an in-depth and public analysis of the actual risks ofnuclear accidents. In light of our findings I believe aninternationally coordinated phasing out of nuclear energy shouldalso be considered ," adds the atmospheric chemist. We are high quality suppliers, our products such as China Corrugated Carton Box , Cardboard Dump Bin for oversee buyer. To know more, please visits Cardboard Display Stand.
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