The BBC informs that, UN nuclear monitors have advised Japan to consider expanding the evacuation zone around the stricken reactors at the Fukushima Daiichi plant
An exclusion zone with a radius of 20km (12 miles) is currently in place but the UN says safe radiation limits have been exceeded 40km away.
Meanwhile, radioactive iodine levels in seawater near the plant reached a new record - 4,385 times the legal limit.
It was the highest reading since the quake which hit the plant on 11 March.
Radioactive material may be leaking from the damaged plant continuously, the country's nuclear and industrial safety agency (Nisa) said.
The plant's operator, Tokyo Electric Power (Tepco), announced on Wednesday that the four stricken reactors would be decommissioned.
The huge quake, and the tsunami it triggered, are now known to have claimed more than 11,000 lives, with at least 16,000 people still reported missing by police, three weeks on.
The UN's nuclear watchdog (International Atomic Energy Agency, IAEA) found safe radiation limits had been exceeded at the village of Iitate, 40km north-west of the nuclear plant.
