ZAO, Japan – Helicopters are dumping water on a stricken reactor in northeastern Japan to cool overheated fuel rods inside the core.
The crisis at several reactors of the Fukushima Dai-ichi plant were set off when last week's earthquake and tsunami knocked out power needed for their cooling systems and ruined backup generators.
Japanese officials struggling to avoid full meltdowns have raised hopes of easing the crisis, saying they may be close to to bringing power back to the plant and restoring the cooling systems.
THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.
FUKUSHIMA, Japan (AP) — Nuclear plant operators trying to avoid complete reactor meltdowns said Thursday that they were close to finishing a new power line that could end Japan's crisis, but several ominous signs have also emerged: a surge in radiation levels, unexplained white smoke and spent fuel rods that U.S. officials said might be on the verge of spewing more radioactive material.
As fear, confusion and unanswered questions swirled around the Fukushima Dai-ichi complex, and Japan suffered myriad other trials from last week's earthquake and tsunami believed to have killed more than 10,000, its emperor took the unprecedented step of directly addressing his country on camera, urging his people not to give up.
"It is important that each of us shares the difficult days that lie ahead," Akihito said Wednesday. "I pray that we will all take care of each other and overcome this tragedy."
The 77-year-old emperor expressed his own deep concern about the "unpredictable" nuclear crisis. "With the help of those involved I hope things will not get worse," he said.
U.S. Nuclear Regulatory Commission Chairman Gregory Jaczko said at a congressional hearing in Washington that all the water is gone from the spent fuel storage pond of Fukushima Dai-ichi's Unit 4 reactor, but Japanese officials denied it. Hajime Motojuku, a spokesman for plant operator Tokyo Electric Power Co., said the "condition is stable" at Unit 4.
Earlier, however, another utility spokesman said officials' greatest concerns were the spent fuel pools, which lack the protective shells that reactors have.
"We haven't been able to get any of the latest data at any spent fuel pools. We don't have the latest water levels, temperatures, none of the latest information for any of the four reactors," Masahisa Otsuki said.
If Jaczko is correct, it would mean there's nothing to stop the used fuel rods from getting hotter and ultimately melting down. The outer shells of the rods could also ignite with enough force to propel the radioactive fuel inside over a wide area.
"My understanding is there is no water in the spent fuel pool," Jaczko told reporters after the hearing. "I hope my information is wrong. It's a terrible tragedy for Japan."
He said the information was coming from NRC staff in Tokyo who are working with the utility in Japan. He said the staffers continue to believe the spent fuel pool is dry.
Other countries have complained that Japan has been too slow and vague in releasing details about its rapidly evolving crisis at complex of six reactors along Japan's northeastern coast, which was ravaged by Friday's magnitude-9.0 earthquake and subsequent tsunami.
The chief of the U.N. nuclear agency, Yukiya Amano, said he would go to Japan to assess what he called a "very serious" situation and urged Tokyo to provide better information to his organization.
Several countries have advised their citizens to consider leaving Tokyo and earthquake-affected areas. The White House recommended Wednesday that U.S. citizens stay 50 miles (80 kilometers) away from the Fukushima Dai-ichi plant, not the 20-mile (32-kilometer) radius recommended by the Japanese government.
Japanese officials raised hopes of easing the crisis, saying early Thursday that they may be close to bringing power back to the plant and restoring the reactors' cooling systems. The earthquake and tsunami knocked out power and ruined backup generators.
The new power line would revive electric-powered pumps, allowing the company to control the rising temperatures and pressure that have led to at least partial meltdowns in three reactors. The company is also trying to repair its existing disabled power line.
Tokyo Electric Power spokesman Naoki Tsunoda said the new power line to the Fukushima Dai-ichi plant is almost finished and that officials plan to try it "as soon as possible," but he could not say exactly when.
Conditions at the plant appeared to worsen, meanwhile. A surge in radiation levels forced workers to retreat for hours Wednesday, costing them valuable time.
The radiation spike was believed to have come from Unit 3, but officials acknowledged they were far from sure what was going on there or at other troubled reactors, in part because high radiation levels made it difficult to get very close.
About 180 emergency workers have been working in shifts to manually pump seawater into the overheating reactors to cool them and stave off complete meltdowns. They were emerging as heroes as their sacrifices became clearer, and as they stepped into circumstances in which no radiation suit could completely protect them.
Japan's health ministry made what it described as an "unavoidable" change Wednesday, more than doubling the amount of radiation to which the workers can be legally exposed.
"I don't know any other way to say it, but this is like suicide fighters in a war," said Keiichi Nakagawa, associate professor of the Department of Radiology at the University of Tokyo Hospital.
Late Wednesday, government officials said they asked special police units to bring in water cannons — normally used to quell rioters — to spray water onto the spent fuel storage pool at Unit 4. The cannons are thought to be strong enough to allow emergency workers to remain a safe distance from the complex, said Minoru Ogoda of Japan's nuclear safety agency.
Tokyo Electric Power said it was also considering using military helicopters to douse the reactors with water, after giving up on such a plan because of high radiation levels in the atmosphere.
Units 1, 2 and 3 of Fukushima Dai-ichi have all been rocked by explosions, and officials have acknowledged that their cores have begun to melt down. Compounding the problems, a fire broke out Tuesday and Wednesday in the Unit 4 fuel storage pond, causing radioactivity to be released into the atmosphere. Temperatures also have been rising in Units 5 and 6.
White smoke was seen rising Wednesday above Unit 3, but officials could not ascertain the source. They said it could be spewing from the reactor's spent fuel pool or may have been from damage to the reactor's containment vessel, a protective shell of thick concrete.
The nuclear crisis has partly overshadowed the human tragedy caused by Friday's massive earthquake, one of the strongest recorded in history.
Millions of Japanese have been with little food and water in heavy snow and rain. In some towns, long lines of cars waited outside the few open gas stations, with others lined up at rice-vending machines.
More than 4,300 people are officially listed as dead, but officials believe the toll will climb to well over 10,000. Police say more than 452,000 people are staying in temporary shelters such as school gymnasiums.
The threat of nuclear disaster only added to Japanese misery and frustration.
"The anxiety and anger being felt by people in Fukushima have reached a boiling point," the governor of Fukushima prefecture, Yuhei Sato, fumed in an interview with NHK. He criticized preparations for an evacuation if conditions worsen, and said centers do not have enough hot meals and basic necessities.
In the city of Fukushima, about 40 miles (60 kilometers) inland from the nuclear complex, hundreds of harried government workers, police officers and others struggled to stay on top of the situation in a makeshift command center.
An entire floor of one of the prefecture's office buildings had been taken over by people tracking evacuations, power needs, death tolls and food supplies.
Elevated levels of radiation were detected well outside the 20-mile (30-kilometer) emergency area around the plants. In Ibaraki prefecture, just south of Fukushima, officials said radiation levels were about 300 times normal levels by late Wednesday morning. It would take three years of constant exposure to these higher levels to raise a person's risk of cancer.
A little radiation has also been detected in Tokyo, triggering panic buying of food and water.
Given the reported radiation levels, John Price, an Australian-based nuclear safety expert, said he saw few health risks for the general public so far. But he said he was surprised by how little information the Japanese were sharing.
"We don't know even the fundamentals of what's happening, what's wrong, what isn't working. We're all guessing," he said. "I would have thought they would put on a panel of experts every two hours."
Chief Cabinet Secretary Yukio Edano said the government expects to ask the U.S. military for help, though he did not elaborate. He said the government is still considering whether to accept offers of help from other countries.