Thread: US experts fear 'Chernobyl-like' crisis for Japan

channelnewsasia

US experts fear 'Chernobyl-like' crisis for Japan

WASHINGTON - US nuclear experts warned Saturday that pumping sea water to cool a quake-hit Japanese nuclear reactor was an "act of desperation" that may foreshadow a Chernobyl-like disaster.

Several experts, in a conference call with reporters, also predicted that regardless of the outcome at the Fukushima No. 1 atomic plant crisis, the accident will seriously damage the nuclear power renaissance.

"The situation has become desperate enough that they apparently don't have the capability to deliver fresh water or plain water to cool the reactor and stabilize it, and now, in an act of desperation, are having to resort to diverting and using sea water," said Robert Alvarez, who works on nuclear disarmament at the Institute for Policy Studies.

"I would describe this measure as a 'Hail Mary' pass," added Alvarez, using American football slang for a final effort to win the game as time expires.

An 8.9 magnitude earthquake that struck Japan on Friday set off the emergency at the plant, which was then hit by an explosion Saturday that prompted an evacuation of the surrounding area.

Workers doused the stricken reactor with sea water to try to avert catastrophe, after the quake knocked out power to the cooling system.

What occurred at the plant was a "station blackout," which is the loss of offsite air-conditioning power combined with the failure of onsite power, in this case diesel generators.

"It is considered to be extremely unlikely but the station blackout has been one of the great concerns for decades," said Ken Bergeron, a physicist who has worked on nuclear reactor accident simulation.

"We're in uncharted territory," he said.

The reactor has been shut down but the concern is the heat in the core, which can melt if it is not cooled. If the core melts through the reactor vessel, Bergeron explained, it could flow onto the floor of the containment building. If that happens, the structure likely will fail, the experts said.

"The containment building at this plant is certainly stronger than that at Chernobyl but a lot less strong than at Three Mile Island, so time will tell," he said.

Peter Bradford, former member of the US Nuclear Regulatory Commission (NRC), said that if the cooling attempts fail, "at that point it's a Chernobyl-like situation where you start dumping in sand and cement."

The two worst nuclear accidents on record are the 1986 Chernobyl disaster in Ukraine and the partial core meltdown of the Three Mile Island reactor in the US state of Pennsylvania in 1979.

Early Sunday, nuclear plant operator Tokyo Electric Power said radiation levels had surpassed the legal limit at its Fukushima No. 1 plant, hit by a blast the previous day, Kyodo News reported.

"If it continues, if they don't get control of this and... we go from a partial meltdown of the core to a full meltdown, this will be a complete disaster," Joseph Cirincione, the head of the Ploughshares Fund, told CNN.

Cirincione said the presence of radioactive cesium in the atmosphere after the plant was vented indicated that a partial meltdown was under way.

"That told the operators that the fuel rods had been exposed, that the water level had dropped below the fuel rods and the fuel rods were starting to burn, releasing cesium," he said.

Japan's nuclear safety agency rated the Fukushima accident at four on the International Nuclear Event Scale from 0 to 7. The Three Mile Island accident was rated five while Chernobyl was a seven.

The government declared an atomic emergency and said tens of thousands of people living within 12 miles (20 kilometers) of the plant should leave after an explosion at the nuclear plant Saturday.

Paul Gunter is the US organization Beyond Nuclear, told Fox News that the evacuation zone might be too small: "If that containment is lost... this will spread a tremendous amount of radioactivity, and it will then be borne on the weather."

The NRC said it has sent two experts to Japan -- experts in boiling water nuclear reactors who are part of a broader US aid team sent to the disaster zone.

Bradford, the former NRC member, said: "This is obviously a significant setback for the so-called nuclear renaissance."

"The image of a nuclear power plant blowing up before your eyes on the television screen is a first."

But World Nuclear Association spokesman Ian Hore-Lacy told CBS News that the threat of a full meltdown is minimal.

"That possibility is remote at the best of times and is diminishing by the hour as the fuel gets cooler and generates less heat," he said.

Source: http://www.channelnewsasia.com/stories/ ... 49/1/.html

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This is really frightening. The relatively small landmass of the world's third largest economy might soon have to be evacuated for thousands of years.

Originally Posted by loservillelabor

This is really frightening. The relatively small landmass of the world's third largest economy might soon have to be evacuated for thousands of years.

=========================

Volcano erupts in Southern Japan


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70% of a 7+ earthquake within the next five days.
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Second massive quake could strike in next three days

news.scotsman
By Jane Bradley

JAPAN is bracing itself to be rocked by a second powerful earthquake, as authorities warned that the death toll from Friday's disaster could rocket to tens of thousands.

Seismologists said a series of tremors, of a greater magnitude than the quake which hit New Zealand in February, could continue to batter the country for months, following the magnitude 9 earthquake and resulting tsunami, which devastated the country

And even larger full-scale earthquakes could become common in the area over several years as a result of damage to the fault line, experts added.

An aftershock of just one point lower than last week's quake - Japan's biggest ever - is predicted to hit the country at any time. Japan's meteorological agency warned there is a strong chance of a second quake within the next three days.

Meanwhile, officials said the death toll could run into tens of thousands as rescuers struggle to find people buried under the rubble.

More than 1,400 people have been killed and thousands more are still missing - but police in one of the worst-hit areas estimated the toll there alone could eventually top 10,000.

Almost two million households were without power in the freezing north of the country, according to official figures from the Japanese government. There were about 1.4 million without running water, while up to 300,000 people had been evacuated from their homes, nationwide.

A grim-faced prime minister Naoto Kan described the crisis at Japan's worst since the end of the Second World War in 1945, as officials confirmed that three nuclear reactors were at risk of overheating, raising fears of an uncontrolled radiation leak.

"The earthquake, tsunami and the nuclear incident have been the biggest crisis Japan has encountered in the 65 years since the end of World War II," Mr Kan said yesterday.

"We're under scrutiny on whether we, the Japanese people, can overcome this crisis."

Japan was faced with another natural phenomenon, after the Shinmoedake volcano yesterday resumed activity following a quiet couple of weeks, spewing ash, gas and rock out on to Kyushu island.

It was unclear if the eruptions, in southern Japan, around 950 miles from the epicentre of Friday's quake, were linked to the ongoing seismic disruption. Japan lies on the "Ring of Fire" - an arc of seismically active zones where earthquake and volcanic eruptions are common.

"There is still the potential for a large aftershock," said Glenn Ford, a senior seismologist at the British Geological Survey in Edinburgh.

"You get a decay process going on with earthquakes and there is usually a shock of around one unit less in magnitude fairly close to the original earthquake, so we could be seeing a quake of around eight or so over the next few days.

"They are very difficult to predict, and in Japan we have already seen a lot of smaller - albeit still large - shocks being released."

He pointed out that Japan had already suffered aftershocks bigger than the magnitude 6.4 quake experienced in Christchurch a month ago, when more than 100 people were killed, adding that further shocks of as high as 6.5 or 7 are likely to continue well into the year.

Experts have warned that a second tsunami resulting from the aftershock cannot not be ruled out, although the Japanese government yesterday lifted tsunami warnings for the country's Pacific coast.

Mr Ford said the country, which is used to experiencing a large number of earthquakes every year, could be worse hit by the expected aftershock than usual, due to the devastation already caused by last week's events.

"The infrastructure in Japan is used to withstanding large earthquakes," he said. "The buildings are built to survive. However, the fact they have already been damaged by such a huge earthquake, means there could be a massive amount of damage - they could be hanging on now, but having experienced movement in the first quake, they might not make it."

The French embassy yesterday urged its citizens to leave the area around Tokyo - 170 miles from the Fukushima Daiichi nuclear power plant, where the earthquake has caused damage to nuclear reactors, sparking radiation fears - in case the crisis deepened and a "radioactive plume" headed for the area around the capital.

Meanwhile, Britain's Foreign Office has established a dedicated crisis unit and has recommended against all non-essential travel to Tokyo and north-east Japan.

But Noriyuki Shikata, of the Japanese prime minister's office, said there was no need for evacuation.

Naoto Takeuchi, chief of police of the Miyagi prefecture, told Japanese state broadcaster NHK that he had "no doubt" there would be 10,000 fatalities in his prefecture alone.

In the small port town of Minamisanriku, which was practically swept away by the tsunami on Friday, some 10,000 people were missing, reports claimed yesterday.

Ian Hanson, senior lecturer in forensic archaeology at Bournemouth University, who is on sabbatical at the International Commission on Missing Persons, said he was hopeful the figure would drop as more people were found alive.

"Often with disaster situations, numbers of people reported missing are very high initially - but this is often because multiple agencies are collecting information and individual missing people will be reported multiple times."

Source: http://news.scotsman.com/news/Second-ma ... 6733520.jp

Nikkei 225 down 6.2% as nuclear fears mount
http://www.ftadviser.com/InvestmentAdvi ... -mount.jsp

Japan's benchmark Nikkei 225 index closed down 6.2 per cent this morning, as a new explosion raised fears of a nuclear meltdown at one of its earthquake-battered power plants.

Japan's nightmare gets even WORSE: All THREE damaged nuclear reactors now in 'meltdown' at tsunami-hit power station

http://www.dailymail.co.uk/news/art ... losion-rips-nuclear-plant.html

By Richard Shears

Last updated at 4:13 PM on 14th March 2011

The Japanese nuclear reactor hit by the tsunami went into 'meltdown' today, as officials admitted that fuel rods appear to be melting inside three damaged reactors.

There have been explosions inside two over-heating reactors at the Fukushima Dai-ichi nuclear plant, and the fuel rods inside a third were partially exposed as engineers desperately fight to keep them under control after the quake knocked out emergency cooling systems.

Japanese chief cabinet secretary Yukio Edano said it was 'highly likely' that the fuel rods inside the reactors are melting.

Some experts class that a partial meltdown of the reactor, but others would only use that term for times when nuclear fuel melts through a reactor's innermost chamber but not through the outer containment shell.

Japan is fighting to avoid a nuclear catastrophe after the tsunami. There was a hydrogen explosion at the reactor in Unit Three of the power station earlier today, in which eleven workers were hurt by the blast that was felt 25 miles away. Melting fuel rods: An aerial view of Fukushima Dai-Ichi nuclear power plant where three over-heating reactors have gone into 'partial meltdown'

Melting fuel rods: An aerial view of Fukushima Dai-ichi nuclear power plant, where three over-heating reactors have gone into 'partial meltdown' Fireball: A build-up of hydrogen in Unit Three of Fukushima ignites in a ball of fire that can be seen for miles

Fireball: A build-up of hydrogen in Unit Three of Fukushima ignites in a ball of fire that can be seen for miles

Smoke: An enormous cloud rises from the site, dwarfing the plant and raising fears of radiation problems

Smoke: An enormous cloud rises from the site, dwarfing the plant and raising fears of radiation problems

Extensive damage: Experts are now debating whether a radiation cloud could reach the West Coast

Extensive damage: Experts are now debating whether a radiation cloud could reach the West Coast Enlarge graphic

Consequences of meltdown: this graphic shows how a full-scale meltdown could affect the United States

U.S. NAVY FLEES RADIOACTIVE PLUME FROM REACTOR BLAST

The Unites States Navy has moved its Seventh Fleet away from an earthquake-stricken Japanese nuclear power plant after detecting raised radiation levels.

The fleet said today that the radiation was from a plume of smoke and steam released from the crippled Fukushima Dai-ichi plant, which has been hit by two explosions since Friday's devastating earthquake and tsunami.

The aircraft carrier USS Ronald Reagan, pictured, was about 100miles (160km) offshore when its instruments detected the radiation.

But the fleet said the dose of radiation was about the same as one month's normal exposure to natural background radiation in the environment. The aircraft carrier USS Ronald Reagan

The reactor at Unit One of Fukushima exploded on Saturday, blowing several walls away but engineers said the core was still contained. The fuel rods in the reactor in Unit Two of the plant were partially exposed from their coolant today - which also increases the risk of meltdown.

Engineers have been fighting to keep the reactors under control after the tsunami knocked out emergency coolant systems on Friday.

Earlier engineers were frantically trying to cool radioactive materials at all the reactors with seawater but had halted the process, which resulted in a rise in radiation levels and pressure.

Plant managers knew an explosion was a possibility as they struggled to reduce pressure inside the reactor containment vessel in Unit Three, but apparently felt they had no choice if they wanted to avoid a complete meltdown.

In the end, the hydrogen in the released steam mixed with oxygen in the atmosphere and set off the blast, which was felt 25 miles away.

The plant's operator Tokyo Electric Company said radiation levels at the reactor were still within legal limits.

Japan's Chief Cabinet Secretary Yukio Edano said the Unit Three reactor's inner containment vessel holding nuclear rods is intact, allaying some fears of the risk to the environment and public.

The government had warned that a further explosion was possible because of the build-up of hydrogen in the building housing the reactor.

More than 180,000 people have been evacuated from the area.

The International Atomic Energy Agency (IAEA) said Japanese authorities reported that radioactivity levels 'at the site boundary' of another nuclear power plant at Onagawa had returned to normal.

Earlier a state of emergency had been declared after the high levels of radiation were detected at the nuclear power complex. Explosion: Smoke rising from the Fukushima number one nuclear plant after a blast in Unit One

Explosion: Smoke rising from the Fukushima number one nuclear plant after a blast in Unit One on Saturday Enlarge Reaching out: A young woman who has been isolated at a makeshift facility to screen, cleanse and isolate people with high radiation levels, looks at her dog through a window in Nihonmatsu, northern Japan

Reaching out: A young woman who has been isolated at a makeshift facility to screen, cleanse and isolate people with high radiation levels, looks at her dog through a window in Nihonmatsu, northern Japan

Thousands of families have been evacuated and many more were yesterday being checked for radiation exposure as Japan began to take stock of what the prime minister labelled its ‘most severe crisis since the Second World War’ – when the U.S. dropped nuclear bombs on Hiroshima and Nagasaki.

Tens of thousands are feared dead, with bodies being picked up from beaches along a 300-mile stretch of coastline.

Others are being gathered from the sea and thousands more are believed to lie buried deep in mud under the debris of homes and cars. At least 10,000 people – half the population of the port of Minami Sanriku – were unaccounted for and the town has been virtually wiped off the map.

Nearby Rikuzentakata was also swamped and destroyed by Friday’s tsunami, killing at least 400 people.

Hundreds of Britons – many of them English language teachers – are among the missing.

Crisis: The nuclear power plant at Fukushima, Japan, where workers are battling to prevent an escalation of the radiation leak and meltdown threat

Crisis: The nuclear power plant at Fukushima, Japan, where workers are battling to prevent an escalation of the radiation leak and meltdown threat Enlarge Three days of nuclear nightmare Damaged: The roof of reactor number one at the Fukushima plant after an explosion that blew off the upper part of the structure

Damaged: The roof of reactor number one at the Fukushima plant after an explosion that blew off the upper part of the structure

Horrific memories: The towns destroyed by the tsunami look very similar to Hiroshima in 1945

Horrific memories: The towns destroyed by the tsunami look very similar to Hiroshima in 1945

Some 100,000 troops and civil defence members, backed by ships and helicopters, yesterday began the mammoth task of clearing rubble and searching for survivors and bodies.

So many people died because when the nine-magnitude Pacific Ocean earthquake struck 80 miles off the coast of Sendai, warnings were issued that a tsunami would hit land in an hour.

But survivors said it struck in nine minutes.

There were warnings last night that strong aftershocks, with a magnitude of six or more, could be expected for at least another week – and Tokyo shuddered several times yesterday as a series of shocks struck the city.

But the gravest consequence of the earthquake and tsunami could yet be felt, as scientists frantically tried to control the threat of nuclear meltdown.

Men in white protective suits and masks swept Geiger counters over frightened survivors yesterday as nuclear experts around the world monitored the crippled and unstable Fukushima plant, 150 miles north of Tokyo.

Up to 200,000 people were evacuated from within a 12-mile radius of the plant, which remains the biggest threat. On the move: Police wearing protective clothing and respirators head towards the the nuclear plant in Minamisouma City, Fukushima Prefecture yesterday

On the move: Police wearing protective clothing and respirators head towards the the nuclear plant in Minamisouma City, Fukushima Prefecture yesterday Sleeping: People who are evacuated from a nursing home which is located in evacuation area around the plant rest at a temporary shelter in Koriyama today

Sleeping: People who are evacuated from a nursing home which is located in evacuation area around the plant rest at a temporary shelter in Koriyama today Map of Japan locating nuclear facilities and radius of a nuclear plant where a explosion occurred on Saturday

Officials revealed that 22 people had already been recorded with radiation poisoning, and they said around 190 were in the plant’s vicinity when radioactive steam was deliberately leaked in an attempt to cool the reactors.

And the words designed to reassure the public that they were in no danger from any leaked radiation were at odds with those from the operator of the plant, Tokyo Electric Power.

The company conceded that radiation levels around the complex had risen above the safety limit but tried to appease the public by stating that it did not mean an ‘immediate threat’ to human health.

It also emerged yesterday that the government ignored explicit warnings from a Japanese expert on nuclear power more than three years ago.

Professor Ishibashi Katsuhiko, of Kobe University, said the guidelines introduced to protect the nuclear plants were ‘seriously flawed’ and that the plants were vulnerable to major quakes.

‘Unless radical steps are taken now to reduce the vulnerability of nuclear power plants to earthquakes, Japan could experience a true nuclear catastrophe in the near future,’ he warned in 2007.

Elsewhere, millions of people are without power and water, factories will remain closed for weeks and Tokyo has been warned there will probably have to be power cuts to conserve electricity.

At rescue centres in Sendai, where people prepared for a third night sleeping on the floor, notice boards are cluttered with the names of the missing.

Weeping survivors said they could only pray that poor communications had failed to put them in touch with their loved ones. One elderly woman reading through one of the lists suddenly exclaimed:’That’s me! They say I’m missing. Well, here I am. My sons must be worried sick about me. But I’m OK.’ Scary scene: Police officers wearing respirators guide people evacuating the area around the plant

Scary scene: Police officers wearing respirators guide people evacuating the area around the plant

Rail services to Sendai and beyond were postponed indefinitely and the only way anyone had any hope of reaching the stricken region was by air, flying to towns on the west coast and attempting to drive across the island. But police have blocked many roads, to keep them clear for rescue vehicles and ambulances.

From the air, rail carriages could be seen lying on their sides. Cars and houses were piled up like debris thrown on to a huge rubbish tip. So how alarmed should we be over this crisis?

By MICHAEL HANLON

Enthusiasts for atomic power are today, inevitably, on the back foot. Those who argue that in the normal course of things nuclear energy is the safest and most reliable form of energy have to contend with a single word: ‘meltdown’.

This is a scenario that brings dread to the hearts of nuclear engineers – an uncontained chain reaction in a reactor core, a blob of molten radioactive metal burning its way out of the containment chamber and a massive release of radioactive fission products such as iodine-131 and strontium-90 into the environment.

It was a partial meltdown which led to the Three Mile Island accident in Pennsylvania in 1978, and a similar explosive breakdown that caused the 1986 Chernobyl disaster.

Both incidents brought strident calls to abandon nuclear power altogether – calls which are bound to intensify following the still-unfolding Japanese catastrophe.

On top of the worst earthquake in its history and a tsunami which may have killed tens of thousands, Japan – a nation which for obvious reasons after the events of 1945 has a love-hate relationship with nuclear power – is staring into the atomic abyss.

What actually caused the accident at Fukushima is still unclear but it seems that in simple terms, the power station was hit by a power cut.

First, seismic detectors at the plant, alerted by the earthquake, triggered an automatic shutdown – by inserting boron rods into the reactor cores, stopping the heat-producing fission reaction.

Normally, the reactor fuel would simply have cooled down safely over a matter of days. But then the tsunami swept through local power grids and back-up generators which provided the electricity for the reactor cooling pumps – possibly fracturing the water main into the plant as well.

Like a car engine with a leaking radiator, the heat started to build up to dangerous levels. Nuclear power stations are essentially huge kettles. You have a power source – the nuclear reactor itself – which gets hot; several hundred degrees in a controlled fission reaction.

The heat is produced by the fission – splitting – of atoms of radioactive materials, such as uranium. Precaution: Officials in protective gear check today for signs of radiation on children who are from the evacuation area near the nuclear plant

Precaution: Officials in protective gear check today for signs of radiation on children who are from the evacuation area near the nuclear plant

This produces not only heat but radiation, and also the creation of radioactive by-products which themselves emit heat as they undergo radioactive decay.

This explains why, even if the primary nuclear reaction is stopped, heat will continue to be generated for days – enough to melt the reactor core if it is not cooled. In normal operation, all this heat is useful – it is used to boil water, which makes steam that is then used to drive electricity-generating turbines.

The problem is that you cannot simply turn off an atomic reactor instantly. It takes days for the red-hot fuel rods to cool down – and that is provided they are supplied with adequate coolant.

Professor Richard Wakeford, a nuclear expert at Manchester University, said yesterday: ‘If the fuel is not covered by cooling water it could become so hot it begins to melt – if all the fuel is uncovered you could get a large-scale meltdown.’

Hopefully this will not happen, and thanks to both the design of the Japanese reactors and to the swift and organised response of the authorities, handing out iodine pills to prevent the ingestion of cancer-causing substances, there is little chance that Fukushima will enter the annals of notoriety alongside Chernobyl.

One possibility which can be discounted is the so-called ‘China Syndrome’, the wholly fictitious idea that a molten reactor core could melt its way through the Earth and emerge on the other side. It is now known that even a total meltdown, although deadly, would soon be contained and cool down naturally. But already questions are being asked – about Japan’s nuclear safety record, and what implications this has outside Japan.

Was it wrong to build a series of atomic reactors so close to the ocean? Experts suggest that given the whole country is an earthquake zone, there is nowhere the plant could be built which would not be at risk.

Unlike Chernobyl, there is no chance that this could become an international incident; Japan is simply too far away from anywhere else for the radiation to spread, and the most serious radioactive contaminant – Iodine-131 – has a half-life of just eight days. Furthermore, the Japanese government is rich, competent and open – which the Soviet authorities in 1986 conspicuously were not.

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THIRD explosion rocks Japanese nuclear plant
By ERIC TALMADGE and MARI YAMAGUCHI, Associated Press Eric Talmadge And Mari Yamaguchi, Associated Press – Tue Mar 15, 12:26 am ET


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SOMA, Japan – Japan's nuclear crisis deepened dramatically Tuesday. As safety officials sought desperately to avert catastrophe, the government said radioactive material leaking from reactors was enough to "impact human health" and the risk of more leaks was "very high."

In a nationally televised statement, Prime Minister Naoto Kan said that radiation has spread from four reactors of the Fukushima Dai-ichi nuclear plant in Fukushima province that was one of the hardest-hit in Friday's 9.0-magnitude earthquake and the ensuing tsunami.

He urged anyone within 19 miles (30 kilometers) of the plant to stay indoors or risk getting radiation sickness.

"The level seems very high, and there is still a very high risk of more radiation coming out," Kan said.

A cascade of three explosions at the Fukushima Dai-ichi nuclear complex was set in motion when last Friday's quake and tsunami knocked out power, crippling the cooling systems needed to keep nuclear fuel from going into full meltdown.

The latest blast was early Tuesday in the plant's Unit 2 near a suppression pool, which removes heat under a reactor vessel, plant owner Tokyo Electric Power Co. said. Shigekazu Omukai, a spokesman for Japan's nuclear safety agency, said the nuclear core was not damaged but that the bottom of the surrounding container may have been.

Chief Cabinet Secretary Yukio Edano said a fourth reactor at the complex was on fire and more radiation had been released.

"Now we are talking about levels that can damage human health. These are readings taken near the area where we believe the releases are happening. Far away, the levels should be lower," he said.

"Please do not go outside. Please stay indoors. Please close windows and make your homes airtight. Don't turn on ventilators. Please hang on your laundry indoors," he said.

"These are figures that potentially affect health, there is no mistake about that," he said.

Japanese officials had previously said radiation levels at the plant were within safe limits, and international scientists said that while there were serious dangers, there was little risk of a catastrophe like Chernobyl in Ukraine, where the reactor exploded and released a radiation cloud over much of Europe.

Unlike the plant in Japan, the Chernobyl reactor was not housed in a sealed container to prevent the release of radiation.

Japanese authorities have been injecting seawater as a coolant of last resort, and advising nearby residents to stay inside to avoid contamination.

"It's like a horror movie," said 49-year-old Kyoko Nambu as she stood on a hillside overlooking her ruined hometown of Soma, about 25 miles (40 kilometers) from the plant. "Our house is gone and now they are telling us to stay indoors.

"We can see the damage to our houses, but radiation? ... We have no idea what is happening. I am so scared."

Earlier blasts Monday and Saturday injured 15 workers and military personnel and exposed up to 190 people to elevated radiation. Officials said those explosions had been linked to the venting of buildups of steam at two of the troubled reactors and that they had not compromised their inner containers.

The nuclear woes compounded challenges already faced by the Tokyo government as it dealt with twin disasters that flattened entire communities and left as many as 10,000 or more dead.

It also raised global concerns about the safety of nuclear power at a time when it has seen a resurgence as an alternative to fossil fuels.

The head of the International Atomic Energy Agency said the Japanese government has asked the agency to send experts to help.

Japan's meteorological agency reported one good sign. It said the prevailing wind in the area of the stricken plant was heading east into the Pacific, which would help carry away any radiation.