It has also stirred unhappy memories of Japan's past nuclear nightmare -- the U.S. atomic bombs dropped on Hiroshima and Nagasaki in 1945. Japan is the only country to have been hit by an atomic bomb.
Further cabling inside was under way before an attempt to restart water pumps needed to cool overheated nuclear fuel rods at the six-reactor Fukushima plant in northeastern Japan, 240 km (150 miles) north of Tokyo.
Working inside a 20 km (12 miles) evacuation zone at Fukushima, nearly 300 engineers were focused on trying to find a solution by restoring power to pumps in four of the reactors.
They managed to restart a diesel pump which they were using to cool reactor No. 5, the nuclear safety agency said.
"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 Co, said in a statement.
Another 1,480 meters (5,000 feet) of cable are being laid inside the complex before engineers try to crank up the coolers at reactor No.2, followed by numbers 1, 3 and 4 this weekend, company officials said.
"If they are successful in getting the cooling infrastructure up and running, that will be a significant step forward in establishing stability," said Eric Moore, a nuclear power expert at U.S.-based FocalPoint Consulting Group.
If that fails, one option under consideration is to bury the sprawling 40-year-old plant in sand and concrete to prevent a catastrophic radiation release.
That method was used to seal huge leakages from the 1986 Chernobyl disaster, the world's worst nuclear reactor disaster.
"Power supply is an absolute necessity," said Michio Ishikawa, former president of the Japan Nuclear Technology Institute. "It will take at least one week for things to stabilize and real stability will take much more time."
Jiji news agency reported the TEPCO had begun using a water pump at reactor No.5.
Underlining authorities' desperation, fire trucks sprayed water overnight in a crude tactic to cool reactor No.3, considered the most critical because of its use of mixed oxides, or mox, containing both uranium and highly toxic plutonium.
"I humbly apologize to the public for causing such trouble. Although it was due to natural disaster, I am extremely regretful," the Mainichi Shimbun newspaper quoted TEPCO CEO Masataka Shimizu as saying in a statement.
Japan has raised the severity rating of the nuclear crisis to level 5 from 4 on the seven-level INES international scale, putting it on a par with the Three Mile Island accident in 1979, although some experts say it is more serious. Chernobyl, in Ukraine, was a 7 on that scale.
SURVIVOR PULLED FROM RUBBLE
The operation to avert large-scale radiation has overshadowed the humanitarian aftermath of the 9.0-magnitude quake and 10-meter (33-foot) tsunami that struck on March 11.
The survivor, a young man, was pulled from the rubble in the city of Kesennuma in Miyagi prefecture, which was one of the hardest-hit regions, the military said. He was in shock and unable to speak.
Nearly 7,000 people have been confirmed killed in the double natural disaster, which turned whole towns into waterlogged and debris-shrouded wastelands.
Another 10,700 people are missing with many feared dead.
Some 390,000 people, including many among Japan's aging population, are homeless and battling near-freezing temperatures in shelters in northeastern coastal areas.
Food, water, medicine and heating fuel are in short supply and a Worm Moon, when the full moon is at its closest to Earth, may bring floods to devastated areas where the geography has been changed by the disaster.
"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.
Health officials and the U.N. 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."
Though there has been alarm around the world, experts have been warning there is little risk of radiation at dangerous levels spreading to other nations.
The U.S. government said "minuscule" amounts of radiation were detected in California consistent with a release from Japan's damaged facility, but there were no levels of concern.
Amid their distress, Japanese were proud of the 279 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, told Reuters.
The plight of the homeless worsened following a cold snap that brought heavy snow to the worst-affected areas.
Nearly 290,000 households in the north were still without electricity, officials said, and the government said about 940,000 households lacked running water.
Aid groups say most victims are getting help, 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," Stephen McDonald of Save the Children said in a statement.
(Additional reporting by Linda Sieg, Nathan Layne, Elaine Lies, Leika Kihara, Nick Macfie, Jon Herskovitz, Joseph Radford and Chris Gallagher in Japan; Fiona Ortiz in Madrid and; Scott DiSavino in New York; Writing by Andrew Cawthorne; Editing by Jonathan Thatcher)
