Nuclear reactors utilize control rods made from elements such as cadmium, boron or hafnium, all of which are efficient neutron absorbers. The way to cut off a fission chain reaction, then, is to intercept the neutrons. 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. 3 at the Fukushima Daiichi station runs on so-called mixed oxide (MOX) fuel, in which uranium is mixed with other fissile materials such as plutonium from spent reactor fuel or from decommissioned nuclear weapons. Enriched uranium is manufactured into fuel rods that are encased in metal cladding made of alloys such as zirconium. (Isotopes are variants of elements with different atomic masses.) Uranium 238 is much more common in nature than uranium 235 but does not fission well, so fuel manufacturers boost the uranium 235 content to a few percent, which is enough to maintain a continuous fission reaction and generate electricity. Most nuclear reactors use uranium fuel that has been "enriched" in uranium 235, an isotope of uranium that fissions readily. electricity comes from nuclear power plants, making it the third-largest source of electricity in the country after coal (45 percent) and natural gas (23 percent). produces more nuclear power overall, but nuclear constitutes a smaller share of its energy portfolio. Worldwide, nuclear energy accounts for about 15 percent of electricity generation Japan gets nearly 30 percent of its electricity from its nuclear plants. 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 1970s. and France, according to data from the International Atomic Energy Agency. With 54 nuclear reactors generating 280 billion kilowatt-hours annually, Japan is the world's third-largest producer of nuclear power, after the U.S. How much electricity does nuclear power provide in Japan and elsewhere? The chain reaction becomes self-sustaining, producing a steady supply of heat to boil water, drive steam turbines and thereby generate electricity. If another atom absorbs one of those neutrons, the atom becomes unstable and undergoes fission itself, releasing more heat and more neutrons. They rely on harnessing nuclear fission-the splitting of an atom into two smaller atoms, which also yields heat and sends neutrons flying. It was treated and diluted through a filtration process called Advanced Liquid Processing System (ALPS) and stored in specially prepared tanks.Īs of June, there were some 1,000 of these tanks holding more than a million cubic meters of treated water.Īn IAEA report issued last month said Japan’s approach and activities to discharge the treated water were “consistent with relevant international safety standards”.įurthermore, the “controlled, gradual discharges” of the treated water would have a “negligible radiological impact” on people and the environment.Most nuclear reactors, including those at Japan's Fukushima Daiichi generating station, are essentially high-tech kettles that efficiently boil water to produce electricity. The water came in contact with melted fuel, fuel debris and other radioactive substances, resulting in contamination. Groundwater also seeps into the site, and rainwater falls into the damaged reactor and turbine building. Since then, water has continually been pumped in to cool the plant's reactors. The Fukushima Daiichi Nuclear Power Station suffered major damage during an earthquake and tsunami in March 2011. “The IAEA has committed to be present before, during and after this process,” Director General Rafael Mariano Grossi said in a video statement. The IAEA has been providing real-time data on the controlled release of the treated water, including on water flow rates and radiation monitoring. The decision to release the water into the sea has sparked criticism in Japan and the region.
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