Updated at 12:31 p.m. ET
FUKUSHIMA, Japan - Containment at three reactors at Japan's crippled nuclear plants is currently intact, U.S. nuclear regulators said, although a plume of smoke from two buildings Monday temporarily stalled critical work to reconnect power lines and restore cooling systems.
Workers are racing to bring the nuclear plant under control, but the process is proceeding in fits and starts, stalled by incidents like the smoke and by the need to work methodically to make sure wiring, pumps and other machinery can be safely switched on.
"Our crisis is still going on. Our crisis is with the nuclear plants. We are doing everything we can to bring this to an end," Gov. Yuhei Sato of Fukushima prefecture, where the plant is located, told some 1,400 people moved away from areas around the plant to a gymnasium 50 miles away. "Don't give up. We know you are suffering."
"Please get us out of here," yelled Harunobu Suzuki, a 63-year-old truck driver.
What caused the smoke to billow first from Unit 3 at the Fukushima Dai-ichi plant and later from Unit 2 is under investigation, nuclear safety agency officials said. Workers were evacuated from the area to buildings nearby, and officials said they were checking radiation levels. In the days since the March 11 earthquake and tsunami wrecked the plant's cooling systems, both reactors have overheated and seen explosions.
Meeting in Washington for an update on conditions at Fukushima, the U.S. Nuclear Regulatory Commission said units 1, 2 and 3 have all seen damage to their reactor cores, but the containment structures are holding. The assessment dispels some concerns about Unit 2, where an explosion damaged a pressure-reducing chamber around the bottom of the reactor core.
"I would say optimistically that things appear to be on the verge of stabilizing," said Bill Borchardt, the commission's executive director for operations.
Problems set off by the disasters have ranged far beyond the devastated northeast coast and the wrecked nuclear plant, handing the government what it has called Japan's worst crisis since World War II. Rebuilding the damage may cost as much as $235 billion. Police estimate the death toll will surpass 18,000.
Traces of radiation are tainting vegetables and some water supplies, causing the government to ban sale of raw milk, spinach and canola from prefectures over a swath from the plant toward Tokyo. The government has just started to test fish and shellfish.
Although the government and health experts say the small amounts do not pose a risk to human health in the short-term, China, Japan's biggest trading partner, ordered testing of Japanese food imports for radiation contamination. The World Health Organization said Japan will have to do more to reassure the public about food safety.
"Walking outside for a day and eating food repeatedly are two different things. This is why they're going to have to take some decisions quickly in Japan to shut down and stop food being used completely from zones which they feel might be affected," said WHO spokesman Gregory Hartl.
The troubles at Fukushima have in some ways overshadowed the natural catastrophe, threatening a wider disaster if the plant spews more concentrated forms of radiation than it has so far.
The nuclear safety agency and Tokyo Electric reported significant progress over the weekend and Monday. Electrical teams, having finished connecting three of the plant's six units, worked to connect the rest by Tuesday, the utility said.
Once done, however, pumps and other equipment have to be checked and the reactors cleared of dangerous gas before the power can be restored. For instance, a motorized pump to inject water into Unit 2's overheated reactor and spent fuel storage pool needs to be replaced, said Hidehiko Nishiyama, an official at the Nuclear and Industrial Safety Agency, or NISA.
If efforts to get the cooling pumps up and running don't work, the government may have to consider taking drastic measures - encasing the entire plant in sand and concrete as was done in the Chernobyl disaster, CBS News correspondent Bill Whitaker reports.
"Well, I think that idea is one that might happen in the long-term, because the reality is, we've got a lot of damaged spent fuel rods in the reactor cores and in these spent fuel pools and it can be very hard to deal with," Matthew Bunn, a nuclear expert at Harvard's John F. Kennedy School of Government, told CBS' "The Early Show" Monday. "That's not something you could do in a matter of days. It's going to take months to build such a tomb. Right now the key priority is to get all the fuel under water again."
The crisis has brought renewed scrutiny to Tokyo Electric, a wealthy, politically influential utility that has been accused in the past of safety violations. Days before the disaster, a NISA report criticized Tokyo Electric for failing to inspect crucial equipment related to cooling systems at Fukushima, though agency officials refused Monday to draw a link between the inspection lapses and the breakdown of cooling systems after the tsunami.
Radioactive iodine, which breaks down after a week, has been the most widespread contaminant found, but so have traces of cesium, which lasts decades and may cause cancer.
That cesium was likely generated when nuclear fuel rods partially melted last week, NISA's Nishiyama said, and is an indication of potential harm to the environment and how badly damaged some of the reactors are.
Early Monday, the Health Ministry advised Iitate, a village of 6,000 people about 19 miles northwest of the plant, not to drink tap water due to elevated levels of iodine. Ministry spokesman Takayuki Matsuda said iodine three times the normal level was detected there about one twenty-sixth of the level of a chest X-ray in one liter of water.
The World Bank said in a report Monday that Japan may need five years to rebuild from the disasters, which caused up to $235 billion in damage, saying the cost to private insurers will be up to $33 billion and that the government will spend $12 billion on reconstruction in the current national budget and much more later.
Growing concerns about radiation add to the chain of disasters Japan has struggled with since the 9.0-magnitude quake. The resulting tsunami ravaged the northeastern coast. All told, police estimates show more than about 18,400 died. More than 15,000 deaths are likely in Miyagi, the prefecture that took the full impact of the wave, said a police spokesman.
"It is very distressing as we recover more bodies day by day," said Hitoshi Sugawara, the spokesman.
Police in other parts of the disaster area declined to provide estimates, but confirmed about 3,400 deaths. Nationwide, official figures show the disasters killed more than 8,600 people, and leaving more than 13,200 missing, but those two lists may have some overlap.
The disasters have displaced another 452,000, who are in shelters.
In an example of the tsunami's force, the wave swept a collapsed house out of a devastated neighborhood in the city of Ishinomaki and deposited it near a river about 100 yards away. A 16-year-old boy and his grandmother who were trapped inside survived and were rescued Sunday when the boy, Jin Abe, was finally able to crawl out of the smashed home and get the attention of a police patrol. Abe told Japanese broadcaster NHK on Monday from his hospital bed: "I'm so relieved to be rescued."
He and his 80-year-old grandmother, Sumi Abe, were wedged under debris in the kitchen of their smashed two-story home and ate snacks and drank water from the nearby refrigerator as they lay trapped in the debris.