Japanese officials are trying to seal a crack that has been leaking radiation into the ocean from one of the crippled Fukushima reactors.
Tokyo Electric Power Company (TEPCO) said it had found a crack in a concrete pit at its No.2 reactor, generating readings of 1000 millisieverts of radiation per hour in the air inside.
The leaks did not stop after concrete was poured into the pit, and TEPCO is using water-absorbent polymers to prevent any more contaminated water from going out.
The Nuclear and Industrial Safety Agency's deputy director Hidehiko Nishiyama said the crack could be one source of the radiation leaks that have hobbled efforts to quell the damaged reactor.
Long term evacuations
Officials in Japan say the evacuation of residents near the Fukushima nuclear plant will be long-term.
More than 70,000 people have been evacuated from the area and are now living in temporary shelters.
The BBC reports another 136,000 people who live within 20km - 30km of the plant have been encouraged to leave or to stay indoors.
Chief Cabinet Secretary Yukio Edano said the evacuation would be "long-term".
In a televised address, Prime Minister Naoto Kan said he was "prepared for a long-term battle" at the plant - one he said that would be won.
Japan is resisting calls from the International Atomic Energy Agency to expand the exclusion zone around the plant, after it found safe radiation limits had been exceeded at the village of Iitate, 40km away.
TEPCO has said it will review all data on radiation leaked from the plant, citing errors in a computer programme.
Among the measurements called into question was one that showed groundwater containing radioactive iodine concentrations of 10,000 times the government standard, the nuclear safety agency said.
Seawater and air concentrations from this week also are under review.
The BBC reports the radiation has halted shipments of certain vegetables, dairy produce and other foodstuffs from four nearby prefectures. The ministry of health says the list has been widened to include beef.
However, the government insists that no water or food contamination has reached levels that would be harmful to people's health.
More than 11,500 people are confirmed dead and nearly 16,500 remain unaccounted for since the the magnitude 8.9 earthquake and subsequent tsunami on 11 March.
