Tokyo: Japanese engineers hope to stop pumping radioactive water into the sea on Sunday and start moving more highly contaminated water out of a crippled nuclear reactor - a key step in gaining access and restoring the critical cooling system.
An unmanned drone helicopter is scheduled to fly over four reactors at the Fukushima Daiichi plant, north of Tokyo, to video the extent of damage in areas where workers are unable to safely enter due to high radiation.
Japan is struggling to contain the worst atomic crisis since Chernobyl after a massive earthquake and tsunami devastated its northeast March 11, with neighboring countries expressing alarm over possible contamination drifting in their direction.
"There are still numerous aftershocks and there is no room for complacency regarding the situation (at Fukushima Daiichi)," Japan`s Deputy Cabinet Secretary Tetsuro Fukuyama said.
Efforts to regain control of six reactors hit by the 15 meter high tsunami, which caused partial meltdowns to some reactor cores after fuel rods were overheated, has been hindered by 60,000 metric tons of radioactive water.
Workers have poured in seawater to cool fuel rods, but in the process have left the plant flooded with radioactive water which they have pumped back into the sea to make room for much more contaminated water.
"Some of the highly radioactive water will be moved within the plant. But a second and third solution needs to be discovered as water is being pumped in constantly, increasing the total amount," Fukuyama told local television on Sunday.
Neighbours China and South Korea have criticized Japan`s action, reflecting growing international unease over the month-long nuclear crisis and the spread of radiation.
China has banned imports of farm products from 12 areas.
Operator Tokyo Electric Power Co (TEPCO) apologised on Saturday over the crisis.
"I would like to apologies from my heart over the worries and troubles we are causing for society due to the release of radiological materials into the atmosphere and seawater," Sakae Muto, a TEPCO vice president, told a news conference.
Prime Minister Naoto Kan is scheduled to visit Ishinomaki city on Sunday, one of the areas hardest hit by the magnitude 9 earthquake and tsunami which left 28,000 people dead or missing, and northeastern Japan a splintered wreck.
More than 153,000 people affected by the tsunami and radiation are living in school gymnasiums and other evacuation centres. Several tsunami-damaged cities have begun moving families into temporary housing.
Banri Kaieda, a minister whose portfolio includes the nuclear industry, said he hoped evacuees from the radiation zone in Fukushima could visit their homes as soon as possible.
Japan has made evacuation mandatory for people living within a 20 km (12-mile) radius of the crippled reactor and urged those living between 20 km and 30 km from the plant to stay indoors.
"There were expectations among the evacuees that they could return to their homes for one night, but they will only be able to stay for a few hours to gather their personal belongings," Kaieda was quoted by Jiji news agency as saying in Fukushima.
Global radiation concerns
Radiation from Japan spread around the entire northern hemisphere in the first two weeks of the nuclear crisis, according to the Vienna-based Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organisation.
TEPCO engineers say they are far from being in control of the damaged reactors and it could take months to stabilise them and years to clear up the toxic mess left behind.
Nuclear reactor maker Toshiba Corp has proposed a 10-year plan to decommission four of the six damaged reactors at the plant, 240 km (150 miles) north of Tokyo, said Kyodo news agency. But the government has said it was too early to have a "specific road map" for ending the crisis.
Several countries have restricted food imports from Japan over radiation fears as its economy reels from the country`s worst disaster since World War Two.
Food is a tiny part of Japan`s export-oriented economy, but disruptions to its manufacturing and electronics supply chains are reverberating around the world.
Automaker Toyota Motor Corp plans to idle some of US plants late in April, while Honda Motor Co Ltd has extended reduced US production until April 22.
Power blackouts and restrictions, factory shutdowns, and a sharp drop in tourists have hit the world`s most indebted nation, which is facing a damages bill as high as USD 300 billion, making it by far the world`s costliest natural disaster.