Exhausted engineers attached a power cable to the outside of Japan's stricken nuclear station today in a race to prevent deadly radiation from an accident now rated at least as bad as America's Three Mile Island in 1979.
Further cabling inside was underway before an attempt to restart water pumps needed to cool overheated nuclear fuel rods at the six-reactor Fukushima plant in northeastern Japan, 240km north of Tokyo.
Japan's unprecedented multiple crisis of earthquake, tsunami and radiation leak has unsettled world financial markets and prompted international reassessment of nuclear safety.
It has also stirred unhappy memories of Japan's past nuclear nightmare - the US atomic bombs dropped on Hiroshima and Nagasaki in 1945.
Working inside a 20km evacuation zone at Fukushima, nearly 300 engineers were focussed on trying to restore power at pumps in four of the reactors.
"TEPCO has connected the external transmission line with the receiving point of the plant and confirmed that electricity can be supplied," the plant's operator Tokyo Electric Power said in a statement.
Another 1,480 metres of cable are being laid inside the complex before engineers try to crank up the coolers at reactor number two, followed by one, three and four this weekend, company officials added. Should that work , it will be a turning point.
"If they can get those electric pumps on and they can start pushing that water successfully up the core, quite slowly so you don't cause any brittle failure, they should be able to get it under control in the next couple of days," said Laurence Williams, of Britain's University of Central Lancashire.
If those tactics fail, the option of last resort may be to bury the sprawling 40-year-old plant in sand and concrete to prevent a catastrophic radiation release, the method used to seal huge leakages from Chernobyl after a huge blast there.
Japan has raised the severity rating of the nuclear crisis from level four to level five on the seven-level International Nuclear and Radiological Event Scale (INES), putting it on a par with America's Three Mile Island accident in 1979, although some experts say it is more serious. Chernobyl was a seven on that scale.
The operation to avert a large-scale radiation leak has overshadowed the humanitarian aspect of Japan's deepest national crisis since the second World War, after it was struck last Friday by a 9.0-magnitude earthquake and a 10-metre tsunami.
Around 6,500 have been confirmed killed in the double natural disaster, which turned whole towns into waterlogged wastelands, and 10,300 remain missing with many feared dead.
Some 390,000 people, including many among Japan's ageing population, are homeless and battling near-freezing temperatures in makeshift shelters in northeastern coastal areas.
Food, water, medicine and heating fuel are in short supply. "Everything is gone, including money," said Tsukasa Sato, a 74-year-old barber with a heart condition, as he warmed his hands in front of a stove at a shelter for the homeless in Yamada, northern Japan.
Under enormous pressure over its handling of the combination of crises, Japan's government conceded it could have moved faster at the outset.
"An unprecedented huge earthquake and huge tsunami hit Japan. As a result, things that had not been anticipated in terms of the general disaster response took place," chief cabinet secretary Yukio Edano told reporters today.
Health officials and the UN atomic watchdog have said radiation levels in the capital Tokyo were not harmful, but the city has seen an exodus of tourists, expatriates and many Japanese, who fear a blast of radioactive material.
"I'm leaving because my parents are terrified. I personally think this will turn out to be the biggest paper tiger the world has ever seen," said Luke Ridley (23) from London as he sat at Narita international airport using his laptop. "I'll probably come back in about a month."
Amid their distress, Japanese were proud of the 300 or so nuclear plant workers toiling in the wreckage, wearing masks, goggles and protective suits sealed by duct tape.
"My eyes well with tears at the thought of the work they are doing," Kazuya Aoki, a safety official at Japan's Nuclear and Industrial Safety Agency, said.
Even if engineers restore power at the plant, the pumps may be too damaged to work.
The first step will be to restore power to pumps for reactors number one and two, and possibly four, by tomorrow, said Hidehiko Nishiyama, Japan's nuclear safety agency spokesman.
By Sunday, the government expects to connect electricity to pumps for its badly damaged reactor number three - a focal point in the crisis because of its use of mixed oxides, or mox, containing both uranium and highly toxic plutonium. That could be a turning point.
The Group of Seven rich nations, attempting to calm global financial markets after a tumultuous week, agreed today to join in a rare concerted intervention to restrain a soaring yen.
Expectations that Japanese insurers and companies would repatriate billions of dollars in overseas funds to pay for a reconstruction bill that is expected to be much costlier than the one that followed the Kobe earthquake in 1995 also have helped boost the yen.
The plight of those left homeless by the earthquake and tsunami worsened following a cold snap that brought heavy snow to worst-affected areas.
Nearly 320,000 households in the north were still without electricity, officials said, and the government said at least 1.6 million households lacked running water.
Aid groups say most victims are receiving attention, but there are pockets of acute suffering.
"We've seen children suffering with the cold, and lacking really basic items like food and clean water," said Stephen McDonald of Save the Children, in a statement today.
Reuters