Authorities were considering restricting access to the evacuation zone around Japan’s crippled nuclear plant to limit radiation exposure to residents who may want to return to their homes.
“We are considering setting up ‘caution areas’ as an option for effectively limiting entry” to the zone, chief cabinet secretary Yukio Edano said.
It was unclear when the ban might be imposed.
About 70,000-80,000 people were living in the 10 towns and villages within 20km of the Fukushima Dai-ichi plant, which has been leaking radiation after a March 11 earthquake and tsunami wrecked its power and cooling systems.
Tokyo Electric Power Co, the nuclear plant’s operator, has begun pumping highly radioactive water from the basement of one of its turbine buildings to a makeshift storage area in a crucial step toward enabling work on restoring the cooling systems.
Removal of the 25,000t of contaminated water that has collected just in the basement of the turbine building at Unit 2 of the plant is expected to take at least 20 days, nuclear safety officials say.
Fully ridding the plant of 70,000t of contaminated water in its turbine buildings and nearby trenches could take months.
Still, a senior official at the UN nuclear agency suggested the worst of the radiation leaks may be over in the worst nuclear power accident since the 1986 catastrophe in Chernobyl.
The total amount of radiation released is expected to be only a “small increase from what it is today” if “things go as foreseen,” said Dennis Flory, a deputy director general at the International Atomic Energy Agency in Vienna.
IAEA experts are discussing ways to help Japan meet targets laid out in a blueprint for ending the crisis that Tepco released over the weekend. Its plans call for achieving a cold shutdown of the plant within nine months. But government officials acknowledge that setbacks could slow the timeline.
In the meantime, Tepco is continuing to spray water into the reactors and their spent fuel storage pools to help prevent them from overheating and releasing still more radiation.
Tepco plans to use technology developed by French nuclear engineering giant Areva to reduce radioactivity and remove salt from the contaminated water inside the plant so that it can be reused to cool the reactors, said Hidehiko Nishiyama of Japan’s Nuclear and Industrial Safety Agency.
This process would take “several months,” he said.