UN probe major nuclear leaks

A MAJOR international mission to investigate Japan’s wrecked nuclear complex began yesterday as new information suggested that two more reactors suffered a meltdown in the aftermath of the tsunami.

That would mean that all three of the most troubled reactors at the plant have suffered partial meltdowns.

The team of UN nuclear experts met Japanese officials and planned to visit the Fukushima Dai-ichi plant in the coming days to investigate the worst nuclear accident since Chernobyl in 1986 and assess efforts to stabilise the complex by Tokyo’s self-declared deadline of early next year.

Meanwhile, plant operator Tokyo Electric Power Company released a new analysis suggesting fuel rods in the plant’s Units 2 and 3 mostly melted during the early days of the crisis, something that had been suspected but not confirmed.

In addition, some chunks of the fuel appeared to have entered the outer containment chambers, causing some damage.

That suggests that the severity of the accident was greater than officials have acknowledged. Tepco announced similar findings last week about Unit 1.

The revelations indicate that earlier official assessments may have been too optimistic, said Goshi Hosono, director of Japan’s nuclear crisis task force.

Fuel in three of the plant’s six reactors started melting just hours after the March 11 tsunami knocked out cooling systems, prompting huge releases of radiation into the atmosphere — about one 10th of the radiation released from the Chernobyl disaster in 1986, according to a government estimate.

The melted fuel rods, which appear to have fallen into a lump at the bottom of each of the three pressure vessels, currently pose no immediate problem because they are mostly covered with water being pumped into the chamber and are at temperatures far below dangerous levels, officials say.

The plant is still leaking low levels of radiation.