Lighting has been restored at one of the control rooms at Japan's crippled
nuclear plant, domestic media reported today, bringing the operators a step closer to reviving the plant's cooling systems to stop radiation.
A steady source of light will enhance the plant operator's efforts to fix instruments damaged by the powerful earthquake and tsunami earlier this month.
Smoke and steam rose from two of the most threatening reactors at the nuclear plant today, suggesting the battle to avert a disastrous meltdown and stop the spread of radiation was far from over, however.
The world's worst nuclear crisis in 25 years playing out 240km north of Tokyo was triggered by a huge earthquake and tsunami on March 11 that left at least 21,000 people dead or missing.
Technicians working inside an evacuation zone around the stricken Fukushima Daiichi plant on Japan's northeast Pacific coast have attached power cables to all six reactors and started a pump at one of them to cool overheating nuclear fuel rods.
But Kyodo news agency said steam appeared to be rising from reactor No. 2 and white haze was detected above reactor No. 3. There have been several blasts of steam from the reactors during the crisis, which experts say probably released a small amount of radioactive particles.
Plant operator Tokyo Electric Power Co (TEPCO) said later the smoke had turned to steam and it was deemed safe to continue work in bringing the plant under control.
Sea-water near the plant were tested for radiation today. Officials stressed that elevated levels already detected were no cause for worry.
In a desperate attempt to cool the reactors and their spent fuel ponds, workers have sprayed or dumped tonnes of sea-water into the cooling system. But several experts have questioned what happens to the water after that.
"I'm interested to know how this water is being disposed ...if it is being disposed or just allowed to drain to sea," said Najmedin Meshkati, a nuclear and environmental expert at the University of Southern California.
"This is now radioactive waste water. Has there been any measurement of its radiation effect?"
Officials have acknowledged that some of the water spilled back to sea.
Hidehiko Nishiyama, deputy director-general at the Nuclear and Industrial Safety Agency, said the radioactivity in the sea could be both from water used to cool the plant and air-borne particles from the reactors.
"Personally, I think the latter is more likely," he told a news conference.
Kyodo news agency quoted TEPCO as saying levels of radioactive iodine-131 in sea-water samples near the plant yesterday were 126.7 times higher than the limit.
Chief Cabinet Secretary Yukio Edano said on Monday that above-safety levels of radiation had been found in sea-water, but these levels "would still be safe even if you drank sea-water for a year."
"Of course, if this were to continue over a long period, some effects will be seen, so we have instructed relevant ministries to step up monitoring efforts of sea water," he added.
Kyodo said the Ministry of Education, Culture, Sports, Science and Technology would analyse sea-water for radiation at eight locations near the Fukushima plant, while TEPCO also plans to conduct its own studies.
The government has sent a research vessel to waters off Fukushima to take samples.
There was no immediate word whether the elevated radiation levels could be transmitted by seafood from these waters, but the local fishing industry has been wrecked by the quake and tsunami.
"There are no fish coming from the regions that were hit, so no fish (being sold) are contaminated," said Rika Tatsuki of the National Federation of Fisheries Cooperative Associations.
Away from the plant, mounting evidence of radiation in vegetables, water and milk stirred concerns among Japanese and abroad despite officials' assurances that the levels were not dangerous.
Japan has urged some residents near the plant to stop drinking tap water after high levels of radioactive iodine were detected. It has also stopped shipments of milk, spinach and another vegetable called kakina from the area.
Experts say readings are much lower than around Chernobyl after the 1986 accident in Ukraine.
The World Health Organization (WHO) said the radiation impact was more serious than first thought, when it was expected to be limited to 20-30 km from the plant.
However, WHO regional spokesman Peter Cordingley told Reuters there was no evidence of contaminated food reaching other countries.
Japan is a net importer of food but it also exports fruit, vegetables, dairy products and seafood, with its biggest markets in Hong Kong, China and the United States.
China said it was monitoring food imports from Japan and South Korea is expanding inspection of Japanese food. Australia's food regulator said the risk was negligible and no extra restrictions on Japanese food were in place.
Agencies