Most of the water also goes through further processing, including an advanced liquid processing system (ALPS) that strips charged particles out of the water. The beads are then stored as standard radioactive waste. The collected wastewater is filtered through resin beads, which have an electrical charge that attracts radioactive isotopes, including cesium and strontium. How can the wastewater be treated or cleaned? And to make any risk analysis trickier, TEPCO has been vague about the full list of radioactive elements still in the water. TEPCO said in 2018 that the levels of these isotopes in the tanks still exceeded safe limits, despite having gone through several “cleaning” steps. “When the fuel burns,” Cullen explains, “it produces radioactive elements in a predictable way and so a pretty clear picture of what elements are there.” The company says there are potentially up to 62 different radioactive elements in the wastewater, but names only a few, including carcinogenic cesium-137 and strontium-90. What do we know about the radiation in the stockpiled water? TEPCO estimates the site will run out of room for new tanks by 2022, and the contaminated water keeps piling up. There are just over one million tonnes of water in the tanks as of 2020. “TEPCO … has used most of the plant site as a storage area built tanks to hold this water, because really they … don’t have any other option,” Cullen says. While some of this water can be reused in cooling the hot reactors, some must be contained and stored after coming in contact with the reactors. “The fuel is still warm and it still needs to be kept cool.” “That process has continued since 2011,” says Cullen of the pumping. Workers frantically pumped seawater directly over the broken reactors and exposed fuel, leaving highly radioactive water pooling in the buildings and seeping into the groundwater around the plant. Fission sped up until the fuel’s temperature was hot enough to liquefy, and the rods began to literally melt down. When the reactors were damaged, their automatic shutdowns and safeguard systems failed, and so did the cooling systems. Animation by Katrina Pyne Why is water piling up at Fukushima? As each atom splits, it emits neutrons which strike nearby atoms, splitting them in turn. This short animation shows the chain reaction of nuclear fission. Your browser does not support the video element. We’ve unpacked this coastal conundrum with the help of marine chemist and oceanographer Jay Cullen at the University of Victoria, British Columbia. Now the plant has a huge volume of used radioactive water, and nowhere to put it. Workers eventually contained the meltdown, but they’ve had to keep the smoldering site cool for nearly 10 years, pumping water into the ruined buildings. The subsequent tsunami flooded critical operating equipment, and the cooling systems stopped working, triggering a meltdown. The plant’s reactors withstood the damage but lost power. Before the quake, three of Fukushima’s six nuclear reactors were in use and operating smoothly to generate electricity. To keep the fuel cooled and avoid overheating and meltdown, it is immersed in water. Nuclear reactors control fission rates by surrounding the fuel rods with “control rods” that absorb extra neutrons. The resulting heat is used to boil water, which drives steam turbines and generates electricity. In the reactor fuel, this natural ability is harnessed-neutrons collide with other uranium atoms and split them apart in a chain reaction. Uranium is naturally radioactive and undergoes a process called fission-its atoms decay, or split, at a predictable rate, emitting neutrons and heat. Now the Tokyo Electric Power Company (TEPCO), the power plant’s owner, is facing a new problem: what to do with radioactive water piling up at the site.Įach reactor encloses rods of uranium pellets. For nearly a decade, the plant’s workers have cooled the wreckage with water. The disaster at the plant-about three hours’ drive north of Tokyo on the shore of the Pacific Ocean-began with a Magnitude 9.0 earthquake and tsunami that flooded critical control equipment and triggered a meltdown. The word “Fukushima” has become known globally as shorthand for a nuclear disaster that happened at the Fukushima Daiichi Nuclear Power Plant on the coast of Japan in March 2011. Novem| 1,400 words, about 7 minutes Share this article Photo by Richard Atrero de Guzman/AFLO/Alamy Live News Fukushima’s Radioactive Wastewater Dilemma What to do with hundreds of thousands of tonnes of contaminated water? Authored by Ongoing efforts to keep the plant cool during cleanup have generated large volumes of water contaminated with radioactive elements, and this water may soon be released into the ocean. The Fukushima Daiichi Nuclear Power Plant was severely damaged by an earthquake and tsunami in 2011, leading to a meltdown.
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