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Report: Japan kept secret about scary nuclear scenario

The Japanese government kept secret for months a worst-case scenario report predicting a massive release of radioactive materials for a year at the earthquake-crippled Fukushima Daiichi power plant, goverment sources told the Kyodo news agency.

The report, shown first to just a small group of policy makers in late March, said a hydrogen explosion would tear through the No. 1 reactor's containment vessel and force all workers to flee lethal radiation levels. It said residents within 105 miles of the plant would be forced to evacuate. A voluntary evacuation zone would have included Tokyo, about 140 miles away.

There would be no time to carry out needed evacuations, sources said, and officials did not want to spur anxiety, according to the Kyodo article published by the Japan Times.

"The content was so shocking that we decided to treat it as if it didn't exist," a senior government official said.

Then-Prime Minister Naoto Kan decided to quietly bury the report, the sources said. His successor, Yoshihiko Noda, changed the document's status after it leaked so it would become public late last year. 

Three of six reactors at the Fukushima plant melted down after the March 11 earthquake and tsunami knocked out the plant's cooling systems and set off the world's worst nuclear accident since Chernobyl.

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