TOKYO — The Japanese government's worst-case scenario at the height of the nuclear crisis last year warned that tens of millions of people, including Tokyo residents, might need to leave their homes, according to a report obtained by the Associated Press. But fearing widespread panic, officials kept the report secret.
The recent emergence of the 15-page internal document may add to complaints in Japan that the government withheld too much information about the world's worst nuclear accident since Chernobyl.
It also casts doubt about whether the government was sufficiently prepared to cope with what could have been an evacuation of unprecedented scale.
The report was submitted to then-Prime Minister Naoto Kan and his top advisers on March 25, two weeks after the earthquake and tsunami devastated the Fukushima Dai-ichi nuclear power plant, causing three reactors to melt down and generating hydrogen explosions that blew away protective structures.
Workers ultimately were able to bring the reactors under control, but at the time, it was unclear whether emergency measures would succeed. Kan commissioned the report, compiled by the Japan Atomic Energy Commission, to examine what options the government had if those efforts failed.
Authorities evacuated 59,000 residents within 12 miles of the Fukushima plant, with thousands more evacuated from other towns later. The report said there was a chance far larger evacuations could be needed, including Tokyo and its suburbs, about 150 miles south with a population of 35 million people, and other major cities.
After Kan received the report, he and other Japanese officials publicly insisted there was no need to prepare for wider-scale evacuations.
Rumors of the report emerged this month after an outside panel was created to investigate possible coverups. Kyodo News agency first reported on the contents of the document Saturday.
Goshi Hosono, the Cabinet minister in charge of the nuclear crisis, said the government had felt no need to make it public.
"It was a scenario based on hypothesis, and even in the event of such a development, we were told that residents would have enough time to evacuate," Hosono said.
Japanese officials initially denied the reactors had melted down, and have been accused of playing down the health risks of exposure to radiation.