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Nuclear-Waste PileupDeep in an abandoned German salt mine, barrels of nuclear waste lie in a jumbled heap—untouched since the 1970s, when this picture was taken.Since the 1960s the Asse II chambers in Lower Saxony (map) have served as storage sites for more than a hundred thousand barrels of low- to medium-level nuclear waste. Low-level waste isn't considered dangerous to handle, but medium-level waste may need shielding before disposal—such as encasing reactor components in concrete—according to the World Nuclear Association, which promotes nuclear energy.In 2008 reports emerged that water leaking from Asse II since the 1980s is radioactive.(Related: "Radioactive Rabbit Droppings Help Spur Nuclear Cleanup.")Now, amid fears the mine could fill with water—causing radioactive contamination in the region—authorities with Germany's Federal Office for Radiation Protection are making an unprecedented attempt to retrieve and relocate hundreds of tons of waste from the controversial site.

"What we have to do now is find out if it's possible to remove the waste," said agency spokesperson Werner Nording. "This work has never been done anywhere in the world up until now."Assuming all goes well—and after tests for radiation, toxicity, and explosive gases—the agency plans to remove the deadly waste with remotely operated vehicles by 2020.—James Owen

Photograph by Emory Kristof, National Geographic