"(FILES) This file photo taken on March 21, 2011 shows a decommissioned nuclear reactor during the cleanup operations at the Western hemisphere's most contaminated nuclear site in Hanford, Washington.  Hundreds of workers at the nuclear site were ordered to take cover on May 9, 2017, after a tunnel filled with contaminated material collapsed near the facility, federal officials said. Employees at the Hanford Site plant, located about 170 miles (275 kilometers) southeast of downtown Seattle, were sent an alert by management in early morning telling them to ""secure ventilation"" and refrain from ""eating or drinking.""  / AFP PHOTO / MARK RALSTON"
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