"The workers cannot carry out even minimal work at the plant now," said chief government spokesman Yuko Edano, referring to workers who had been dousing the reactors with seawater in a frantic effort to cool down their rising temperatures. "Because of the radiation risk, we are on standby."
Helicopters from Japan's Self Defense Forces were preparing to dump water on the plant's No.3 and No. 4 reactors, but the government canceled the plan after a surveillance helicopter measured excessive radiation levels above the plant, Mr. Edano said.
Later, however, radiation levels dipped and some workers were able to resume cooling efforts.
Today's suspension of efforts comes one day after Japanese officials told the United Nations' International Atomic Energy Agency (IAEA) that radioactivity was "being released directly into the atmosphere" after a fire broke out in a storage pond for spent fuel at the plant's No. 4 reactor.
The IAEA said Wednesday that all the fuel from the No. 4 reactor was transferred last November to the storage pond where Tuesday's fire broke out. The transfer was part of routine maintenance, but the fire there caused the release of radioactivity into the atmosphere.
Until Tuesday, Japanese officials had maintained that radiation levels near the plant were not harmful to humans.
But Tuesday's fire caused them to revise that statement and order 140,000 people living near nuclear power plants damaged to stay indoors and seal their doors and windows.