Radiation 1,000 times normal has been detected at a crippled nuclear plant in northeastern Japan where utility managers have released radioactive steam to reduce mounting reactor pressure, the Kyodo news service is reporting, citing the government’s safety agency.

That suggests radioactivity could spread around Tokyo Electric Power Co.’s Fukushima No. 1 plant, where thousands of residents within a 6-miles were ordered to leave before dawn Saturday.

There’s potential danger to the public from three of at least 11 nuclear power reactors that are shut down because of Friday’s 8.9 earthquake, the Christian Science Monitor reports.

Managers at Fukushima No. 1 said before the planned release of steam that any radiation would be “very low and the safety of nearby residents has been ensured,” Kyodo news service reported earlier. Within the hour ago plant officials said some radiation may have already been released, according to Kyodo.

About 3,000 people within a 2-mile radius had been ordered to leave late Friday, while thousands more within a 6-mile radius were told to stay indoors. Before dawn, however, mandatory evacuations were extended to 6 miles.

Prime Minister Naoto Kan plans to visit the plant later Saturday.

A U.S. nuclear specialist calls it “a dicey situation.”

“They’re operating on battery power now, and if they lose the batteries, they lose core cooling,” Edwin Lyman, with the Union of Concerned Scientists, told the Monitor. He said the military is supposed to be bringing batteries to keep the backup cooling system operating to prevent the reactor’s uranium core from overheating and melting.

(Source: USA Today)