Radioactive steam build-up hits battle to cool reactors

Japan's government claimed some success over the weekend in its battle to prevent a meltdown at a crippled nuclear power plant. But amid reports of spreading contamination, it warned that the release of more radioactive material was likely.

Tokyo Electric Power (Tepco), which operates the Fukushima Daiichi plant, said it had cooled the dangerously overheating spent-fuel pools in rectors No 5 and No 6, and attached power lines to reactors No 1 and No 2, the first step in restarting cooling pumps. But work on reactor No 3 was suspended yesterday after explosive pressure built up inside.

Engineers were mulling last night whether to vent steam inside the container vessel surrounding the reactor, possibly releasing krypton, xenon and other radioactive materials. Officials are already reporting small amounts of radioactive contamination in vegetables, milk and water near the plant and in surrounding prefectures.

Workers spent another day yesterday hosing the badly damaged complex with tons of water, a mission declared "successful" by the government's spokesman Yukio Edano, who announced it would be scrapped after the crisis ends. But experts say it is much too early to declare an end to the fight to bring the plant under control.

"I hope that safety, stability will be recovered as soon as possible... but I still don't think it is time to say that I think they are going in a good direction or not," said International Atomic Energy Agency (IAEA) chief Yukiya Amano, after finishing a two-day visit to Japan.

Tepco's overwhelmed boss, Akio Komiri, burst into tears in front of reporters after a press conference during the weekend where the company reported hiking the radioactivity limit for some workers at the plant from 100 millisieverts to 150 millisieverts. The average exposure for nuclear plant workers in the United States is 50 millisieverts per year.

Mr Edano admitted last week that radiation around the plant was high enough to affect human health. Japan's Nuclear and Industrial Safety Agency has raised its alert level in the crisis to five, meaning that radiation deaths are likely. The decision put the crisis on a par with the 1979 Three Mile Island accident and below the world's worst nuclear disaster in Chernobyl in 1986.

The government is considering whether to limit the sale and consumption of food produced in the area around the Fukushima complex. Some reports say the sale of milk from the prefecture has already been banned. The IAEA yesterday confirmed that radioactivity from the plant had not contaminated food grown outside Japan.

Officials also warned that previous estimates of the death toll from the disaster are probably too low. Police say 15,000 people could have died in Miyagi Prefecture alone, mainly from the tsunami that struck the coast after the quake on 11 March. More than 8,000 people have been confirmed dead.