Tokyo Electric Power Co (TEPCO) workers work on waste water tanks at Japan's Fukushima Daiichi nuclear plant in the town of Okuma, Fukushima prefecture in Japan on June 12, 2013. Noboru Hashimoto /AFP/Getty Images hide caption

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Steam And Groundwater Raise Concern At Japanese Nuclear Plant
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After the earthquake, workers were sent inside Reactor 1 at the Fukushima plant to release some of the pressure building up inside the reactors. Frontline hide caption

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One Year Later, 'Inside Japan's Nuclear Meltdown'
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This March 24 aerial photo shows the extent of damage at the Fukushima Dai-ichi nuclear power plant in Japan. The 40-foot-tall tsunami destroyed the electrical and cooling systems, resulting in meltdowns at some of the reactors. Air Photo Service/AP hide caption

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Reports: Why Things Fell Apart At Fukushima Plant
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Workers at the Fukushima Dai-ichi nuclear power plant spray a substance to help reduce dust on April 1. The cleanup operation at the facility could take more than a decade. TEPCO hide caption

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Cleaning Up Fukushima: A Challenge To The Core
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Manholes poke out from the ground in Urayasu, Japan, due to the liquefaction triggered by the 9.0 magnitude earthquake. The phenomenon, which allows sand and water to rise following ground shaking, was particularly pronounced in this area as a result of the long duration of the March 11 quake. Koki Nagahama/Getty Images hide caption

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In Japan, Shaken Soil Turned Soft After Quake
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TEPCO workers spray synthetic resin over the ground at the plant to prevent radioactive dust from spreading beyond the premises. AP hide caption

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In November 1940, just months after its completion, a large section of the Tacoma Narrows Bridge crashed into Puget Sound in Tacoma, Wash. The bridge collapsed under high winds — a failure that shocked engineers at the time. AP hide caption

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How Safe Is Safe Enough? To Engineers, It Depends
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A Tokyo Electric Power Co. worker looks at gauges in the control room for Units 1 and 2 at the Fukushima Dai-ichi plant, Wednesday. AP Photo/Nuclear and Industrial Safety Agency hide caption

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Many of the sensors and cameras at the nuclear power plant were disabled by explosions, so plant operators are turning to highly maneuverable robots to get a better idea of what's going on in areas where it's far too radioactive for workers to venture. iRobot hide caption

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First Eyes Inside Nuclear Plant May Be A Robot's
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South Korean passengers watch a broadcast of the situation at the Fukushima Dai-ichi nuclear plant from a train station. There have been no major changes to the situation at the nuclear power plant in a few days. Jung Yeon-Je/AFP/Getty Images hide caption

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A boy evacuated from Koriyama, some 37 miles from the Fukushima Dai-ichi plant, gets scanned with a Geiger counter Wednesday. Ken Shimizu/AFP/Getty Images hide caption

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A white cloud rises from reactors at the stricken Fukushima Dai-ichi nuclear power plant on Wednesday. Though the gas contains radiation, experts say any plume that travels out over the ocean won't be of much risk to the West Coast of the U.S. DigitalGlobe hide caption

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Airborne Radiation Poses Minuscule Risk For U.S.
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Nuclear Reactor Redesigns Aim To Allay Safety Fears
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A container of mixed oxide, or MOX, a blend of plutonium and reprocessed uranium, that Japan uses as nuclear fuel for the No. 3 reactor at the Fukushima Dai-ichi plant, is loaded aboard the Pacific Heron ship in the French port of Cherbourg on April 8, 2010. Jean-Paul Barbier/AFP/Getty Images hide caption

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A diagram of the Mark I-type boiling water reactor, like the kind at the Fukushima nuclear facility. Nuclear Regulatory Commission hide caption

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An evacuee is screened for radiation exposure at a testing center on Tuesday in Koriyama city, Fukushima prefecture. Officials are concerned about radiation leaking from the nuclear plant nearby. Wally Santana/AP hide caption

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Explainer: What Are Spent Fuel Rods?
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Technicians at the Three Mile Island plant enter the outer airlock door leading into the containment building housing the disabled nuclear reactor at the Three Mile Island nuclear plan in February 1982. The accident at the Harrisburg, Pa., plant began on March 28, 1979. AP hide caption

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Sizing Up Japan's Nuclear Emergency: No Chernobyl
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