Japan's TEPCO admits further reactor meltdowns (AFP)

TOKYO (AFP) – The operator of Japan's tsunami-hit Fukushima nuclear power plant on Tuesday said it believed fuel had partially melted inside three reactors, as long suspected by experts.

Tokyo Electric Power Company (TEPCO) said new readings on water gauges indicated that the fuel had dropped to the bottom of the containment vessels of units two and three, matching its earlier assessment of unit one.

In all three reactors, relatively low temperatures indicated that the fuel was now mostly covered by water that has been pumped into the vessels, meaning there was no immediate threat of an uncontrolled full meltdown.

"It is highly possible that (partial) meltdowns have occurred at reactors two and three," a TEPCO spokesman said as the firm released its latest analysis of data from the plant after the March 11 quake and tsunami.

"Most of the fuel is believed to have fallen to the bottom (of pressure vessels that contain fuel rods) as has happened in reactor one," he said. "They are now being cooled and are in stable conditions."

Japan's March 11 disaster, which left nearly 25,000 people dead or missing, knocked out cooling systems at the Fukushima plant. This led reactors to overheat, triggering the worst nuclear crisis since Chernobyl 25 years ago.

Reactors four, five and six were under maintenance when the quake hit.

TEPCO estimates it will bring all six reactors to safe "cold shutdown", with low pressure and low temperatures, by some time between October and January, although it will take far longer to dismantle the plant.

Emergency crew have sprayed water into the facility since the quake to cool down the reactors and keep fuel rods in containment pools submerged under water, creating tonnes of toxic runoff that has leaked into the Pacific.

This week TEPCO warned that containment vessels for the radioactive water were almost full.

The company is building a new water treatment facility and has also docked a storage tank called the "megafloat" off the site to hold more low-level contaminated water.

An international panel of nuclear experts arrived in Japan this week to assess the accident and is due to report back to the UN's International Atomic Energy Agency in Vienna in late June.

The IAEA announced last week the mission, headed by Mike Weightman, chief inspector of nuclear installations in Britain, would comprise 20 experts from 12 different countries.

Japan has also decided to set up a panel independent of the nuclear industry and bureaucracy, and mostly made up of academics, to look into the causes of the crisis. It is expected to compile a mid-term report in December and a final report by mid-2012.

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Tepco confirms meltdowns at 2 more Fukushima reactors (Reuters)

TOKYO (Reuters) – The operator of the nuclear power plant at the center of a radiation scare after being disabled by Japan's earthquake and tsunami confirmed Tuesday that there had been meltdowns of fuel rods at three of its reactors.

Tokyo Electric Power Co said meltdowns of fuel rods at three reactors at the Fukushima Daiichi plant occurred early in the crisis triggered by the March 11 disaster.

The government and outside experts had said previously that fuel rods at three of the plant's six reactors had likely melted early in the crisis, but the utility, also known as Tepco, had only confirmed a meltdown at the No.1 reactor.

Tepco officials said a review since early May of data from the plant concluded the same happened to reactors No.2 and 3.

The preliminary finding, which was reported to Japan's nuclear safety agency, represents part of an initial effort to explain how events at Fukushima spiraled out of control early in the crisis.

Also Tuesday, the government appointed Yotaro Hatamura, a Tokyo University professor of engineering who has studied how complex systems and designs fail, to head a committee that will investigate the cause and handling of the nuclear crisis.

The moves came as a team of investigators from the International Atomic Energy Agency began a two-week visit to Japan to prepare a report on the accident to be submitted to the United Nations agency in June.

Some analysts said the delay in confirming the meltdowns at Fukushima suggested the utility feared touching off a panic by disclosing the severity of the accident earlier.

"Now people are used to the situation. Nothing is resolved, but normal business has resumed in places like Tokyo," said Koichi Nakano, a political science professor at Tokyo's Sophia University.

Nakano said that by confirming the meltdowns now, Tepco may be hoping the news will have less impact. The word "meltdown" has such a strong connotation that when the situation was more uncertain more people would likely have fled Tokyo, he said.

Engineers are battling to plug radiation leaks and bring the plant 240 km (150 miles) northeast of Tokyo under control more than two months after the 9.0 magnitude earthquake and deadly tsunami that devastated a vast swathe of Japan's northeast coastline and tipped the economy into recession.

The disaster has triggered a drop of more than 80 percent in Tepco's share price and forced the company to seek government aid as it faces compensation liabilities that some analysts say could top $100 billion.

Japanese trade minister Banri Kaieda said the government would approve the formation of a committee later Tuesday that will make sure Tepco follows through with restructuring plans.

Tepco officials said damage to the No.2 reactor fuel rods had begun three days after the quake, with much of the fuel rods eventually melting and collecting at the bottom of the pressure vessel containing them.

Fuel rods in the No.3 reactor were damaged by the afternoon of March 13, they said.

TSUNAMI

The Tepco officials repeated that the tsunami had disabled power to the reactors and knocked out their cooling capability.

Hidehiko Nishiyama, a spokesman for the government's Nuclear and Industrial Safety Agency, expressed a similar view.

"We don't think the quake affected the important parts of the plant, such as its cooling capacity," Nishiyama told reporters Tuesday, although he added there were still some aspects that needed to be clarified by inspecting the site directly.

That process is likely to make months because of the high radiation readings in areas of the plant, experts have said.

"It could very well be that Tepco is rushing to conclude that the tsunami is to blame to prevent further questions and give more momentum to the nuclear camp. It's not just Tepco, it's the whole nuclear industry, maybe business circles as a whole. It's highly political," said Sophia University's Nakano.

Others said that from a very early stage the tsunami, not the quake, was the likely cause of the overheating and subsequent damage of the reactors at Daiichi.

"As with the other nuclear reactors, such as Onagawa (in northeastern Japan), those at Daiichi deactivated after the quake. It is our belief that it was the tsunami that knocked out power and took out the systems and pumps that cool the reactors, resulting in their damage and radiation leakage," said Kazuhiko Kudo, a Kyushu University professor who specializes in nuclear engineering.

Despite a steady flow of information on how the clean-up is proceeding -- Tepco and the government's nuclear watchdog hold news conferences twice a day on most weekdays -- the authorities have faced criticism for what some have said is a lack of timely disclosure.

"I am very sorry that the public is mistrustful of the various disclosures made by the government on the accident," Prime Minister Naoto Kan said in parliament Monday.

(Additional reporting by Linda Sieg and Yoko Nishikawa; Editing by Chris Gallagher and Michael Watson)

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