There have only been two major accidents at nuclear power plants, and their impacts have been far less severe than widely feared. Nuclear is the safest energy source we use anywhere in the world. The provision of reliable electricity brings huge benefits to society, but its production, like any other industrial activity, is not without risk. In the history of civil nuclear energy, there have only been two major accidents where a large amount of radioactive material was emitted: at Chernobyl , which has resulted in 46 deaths so far, and at Fukushima Daiichi , which resulted in no casualties.
Air pollution from the combustion of fossil fuels, including in power plants, causes 8. In terms of the number of deaths from accidents, hydroelectric power is the deadliest method of generating electricity. It has been concluded in studies conducted by, for example the World Health Organisation, that the radiation health effects of nuclear accidents have been very small.
The main impacts of nuclear accidents were not caused by radiation exposure, but instead were due to psychological and socio-economic factors resulting from misconceptions and fears about radiation — and so could have been largely avoided. Further information can be found on the information page regarding radiation and health effects. A nuclear meltdown is an accident resulting from severe heating and a lack of sufficient cooling at the reactor core, and it occurs in different stages.
As the core heats, the zirconium metal reacts with steam to become zirconium oxide. This oxidation process releases additional heat, further increasing the temperature inside the core. High temperatures cause the zirconium coating that covers the surface of the fuel rods to blister and balloon.
In time, that ultra-hot zirconium metal starts to melt. Exposed parts of the fuel rods eventually become liquid, sink down into the coolant and solidify. A full meltdown would involve all of the fuel in that core melting and a mass of molten material falling and settling at the bottom of the reactor vessel. If the vessel is ruptured, the material could flow into the larger containment building surrounding it. That containment is shielded by protective layers of steel and concrete.
Meltdown can also occur in the pools containing spent fuel rods. Craig F. If society abandons these dry casks, rather than maintaining and replacing them for perpetuity, they will eventually erode and expose the surrounding area to radiation. Compare that to coal power, which produces nearly times that much waste every year in the country of South Africa alone.
In the past, policymakers weighed the risks and doled them out in a way that fell disproportionately on the Navajo and other communities of color. In the future, nuclear plants will only succeed when communities weigh the risks for themselves, and decide they want them, Vestergaard says.
Chinese officials learned this the hard way in , when they decided to build a acre nuclear fuel production park in the industrial Pearl River delta. The government often bulldozes through local objections to development, but in this case the locals won. Contrast that with the underground repository for nuclear waste that recently opened on Olkiluoto Island, Finland. In that case, officials found a community that was open to the idea, then let locals shape the project.
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Nathanael Johnson Science. The Nuclear Option. People tend to have strong opinions about nuclear power. Meet a few who changed their minds. Nathanael Johnson. Eve Andrews. Jena Brooker. If another atom absorbs one of those neutrons, the atom becomes unstable and undergoes fission itself, releasing more heat and more neutrons.
The chain reaction becomes self-sustaining, producing a steady supply of heat to boil water, drive steam turbines and thereby generate electricity. How much electricity does nuclear power provide in Japan and elsewhere? With 54 nuclear reactors generating billion kilowatt-hours annually, Japan is the world's third-largest producer of nuclear power, after the U. The Fukushima Daiichi station, which has been hit hard by the March 11 earthquake, houses six of those reactors, all of which came online in the s.
Worldwide, nuclear energy accounts for about 15 percent of electricity generation; Japan gets nearly 30 percent of its electricity from its nuclear plants. The U. About 20 percent of U. What fuels a nuclear reactor? Most nuclear reactors use uranium fuel that has been "enriched" in uranium , an isotope of uranium that fissions readily.
Isotopes are variants of elements with different atomic masses. Uranium is much more common in nature than uranium but does not fission well, so fuel manufacturers boost the uranium content to a few percent, which is enough to maintain a continuous fission reaction and generate electricity.
Enriched uranium is manufactured into fuel rods that are encased in metal cladding made of alloys such as zirconium. Reactor No. How do you turn off a nuclear reaction?
Sustained nuclear fission reactions rely on the passing of neutrons from one atom to another—the neutrons released in one atom's fissioning trigger the fissioning of the next atom.
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