THE OPERATOR of the Fukushima Daiichi nuclear power plant says it has stopped highly radioactive water from leaking into the Pacific Ocean but is now trying to prevent another explosion in one of the crippled plant’s six reactors.
Tokyo Electric Power Co (Tepco) announced yesterday that it had plugged the leak by injecting thousands of litres of chemical agents near a cracked water pit in reactor 2. Fuel rods inside the reactor’s core are believed to have partially melted down.
Engineers at the plant are also struggling to prevent a potentially catastrophic build-up of hydrogen gas in reactor 1. A similar problem caused a series of explosions that wrecked three of the plant’s reactors after the March 11th earthquake and tsunami knocked out its cooling systems.
The embattled utility has sparked a furious reaction by dumping more than 11,000 tonnes of toxic groundwater from the plant into the sea.
Japan’s national federation of fisheries co-operatives said they were “immeasurably angry” at Tepco and at the government for making the decision without prior consultation.
Analysts say the water is likely to contain iodine, caesium and plutonium 239, in addition to radioactive fuel fragments.
Environmentalists are comparing the release to the aftermath of Britain’s worst nuclear accident at the Windscale (now Sellafield) nuclear plant in 1957.
“Water used to douse the fires [in Windscale] discharged hundreds of thousands of fuel fragments into the North Atlantic,” said Shaun Burnie, a nuclear specialist with Greenpeace Germany.
“From the start of seawater pumping more than three weeks ago, Tepco knew they had a contaminated water problem – and they have not dealt with it. It is disastrous disaster management.”
Tepco faces few easy options as it tries to bring the plant under control. Weeks of pumping water into the reactors in an attempt to cool overheating nuclear fuel have left about 60,000 tons of contaminated water in turbine halls, trenches and elsewhere on site.
The operator admits that it does not have enough tanks to store the water and faces a further build-up in the weeks to come.
Plugging the leak from reactor 2 is a small success for the plant’s engineers, who had earlier tried sawdust, newspapers and a quick-drying bonder before using sodium silicate, or so-called water glass.
However they will probably be forced to dump more “low-radioactive” water into the sea while trying to store the most toxic materials at the plant.
Analysts warn that another major release of radioactivity – in addition to the daily routine discharge – is possible from at least one of the reactors.
The government is playing down expectations that the Fukushima crisis has ended. “Right now, just because the leak has stopped, we are not relieved yet,” said chief cabinet secretary Yukio Edano yesterday. “We are checking whether the leak has completely stopped or whether there may be other leaks.”
Mr Edano has been forced to apologise for the Pacific radioactive discharge after South Korea and other countries protested.
The Chosun Ilbonewspaper led Korean publications in criticising the decision, claiming that Japan informed the United States and the International Atomic Energy Agency beforehand, but "neither consulted nor informed its closest neighbour".
Radioactive iodine 131 has been detected in the seas off the plant at thousands of times legal limits. Japan’s government says the releases pose no long-term health risks, but there has already been a sharp drop in seafood consumption and several countries have introduced controls or banned food imports from Japan.