Updated 11:35 a.m. ET
TOKYO - Workers reconnected power lines to all six reactor units at Japan's radiation-leaking nuclear plant Tuesday, its operator said, marking a significant step in bringing the overheated complex under control.
In making an announcement after days of anxious waiting by the public, Tokyo Electric Power Co. cautioned that much work needed to be done before the electricity can be turned on. Workers are checking all additional equipment for damage to make sure cooling systems can be safely operated, Tokyo Electric said.
In another advance, emergency crews dumped 18 tons of seawater into nearly boiling storage pool holding spent nuclear fuel, cooling it to 105 degrees Fahrenheit (50 degrees Celsius), Japan's nuclear safety agency said. Steam, possibly carrying radioactive elements, had been rising for two days, and the move lessens the chances that more radiation will seep into the air.
Added up, the power lines and concerted dousing bring authorities closer to ending a nuclear crisis that has complicated the government's response to the catastrophic earthquake and tsunami that devastated Japan's northeast coast 11 days ago.
But Tokyo Electric cautioned that workers must check pumps, motors and other equipment before the electricity is turned on. Officials and experts, however, have said days, even weeks would be needed to replace damaged equipment and vent any volatile gas to make sure electricity does not spark an explosion.
"The crucial moment is going to be when they find out whether or not the cooling pumps that are necessary to keep that core of the reactor core are working," James Acton, a nuclear policy expert at the associate Carnegie Endowment for International Peace told CBS' "The Early Show" Tuesday. "Because this is what is needed to really start getting this crisis under control is cooling. And we'll have to see whether or not the pumps are working."
It is unclear how badly the cooling equipment may have been damaged in the earthquake and tsunami that spawned the weeklong nuclear crisis.
Spent fuel pools continue to leak radiation and TEPCO said that contamination has been detected in seawater near the plant for the first time, although so far the levels are said to be extremely low, CBS News correspondent Bill Whitaker reports.
"I think the moving of the U.S. warship is a reflection of the fact that this situation remains serious and that there is the potential for further degradation," Acton said.
But Acton expressed cautious optimism and said that scenarios involving abandoning and entombing the nuclear site are beginning to appear less likely.
"I think we're a length away from abandoning the reactors. Over the last three or four days, we've heard better news," he said. "The fact there was steam coming out of two and smoke coming out of three and the reasons haven't been understood, so that demonstrates this remain as serious crisis. But I think it's receded from the worst of where it was and abandoning the reactors is looking less likely."
Its power supply knocked out by the disasters, the Fukushima Dai-ichi nuclear complex has leaked radiation that has found its way into vegetables, raw milk, the water supply and even seawater across a band of Japan. The resulting fears of radiation mean the impact of the disasters has reverberated well beyond the disaster area and the families of the hundreds of thousands of displaced and of the estimated 18,000 dead.
"We must overcome this crisis that we have never experienced in the past, and it's time to make a nationwide effort," Chief Cabinet Secretary Yukio Edano, the government's public point-man, said earlier Tuesday in his latest remarks meant to soothe public anxieties.
Amid the latest developments, weariness and anxiety percolated among people who left their homes near Japan's radiation-shedding nuclear complex. People at Fukushima city's main evacuation center waited in long lines for bowls of hot noodle soup. A truck delivered toilet paper and blankets. Many among the 1,400 people living in the crowded gymnasium came from communities near the nuclear plant and worry about radiation and weary of the daily routine of the displaced.
"It was an act of God," said Yoshihiro Amano, a grocery store owner whose house is 4 miles from the reactors. "It won't help anything to get angry. But we are worried. We don't know if it will takes days, months or decades to go home. Maybe never. We are just starting to be able to think ahead to that."
Public sentiment is such that Fukushima's governor rejected a meeting offered by the president of TEPCO.
"What is most important is for TEPCO to end the crisis with maximum effort. So I rejected the offer," Gov. Yuhei Sato said on national broadcaster NHK. "Considering the anxiety, anger and exasperation being felt by people in Fukushima, there is just no way for me to accept their apology."
Three of Japan's marquee companies -- Sony Corp., Toyota Motor Corp. and Honda Motor Co. -- announced halts to production at plants in Japan. The reason is a shortage of parts -- a result of so many ruined factories in the disaster area.
Fears about radiation are reaching well beyond those living near Fukushima and the 430,000 displaced by the earthquake and tsunami to encompass large segments of Japan. Traces of radiation are being found in vegetables and raw milk from a swath of farmland, forcing a government ban on sales from those areas.
Seawater near the Fukushima plant is showing elevated levels of radioactive iodine and cesium, prompting the government to test seafood.
China, Japan's largest trading partner, has ordered testing of imports of Japanese food. The World Health Organization has urged Japan to adopt stricter measures and reassure the public.
An American leukemia specialist who worked with the Japanese government following a 1999 nuclear accident told the Japanese press Tuesday that the radioactive material in the atmosphere is about one one-thousandth of the amount seen at Chernobyl -- and that cigarette smoking still poses a greater cancer risk than the possible radiation exposure.
Dr. Robert Gale said the government-established evacuation and danger zones are appropriate but warned that the risks of food contamination could continue for decades and will require further study.
Government officials and health experts say the doses are low and not a threat to human health unless the tainted products are consumed in abnormally excessive quantities. But the government measures to release data on radiation amounts, halt sales of some foods and test others are feeding public worries that the situation may grow more dire.
"We acknowledge this situation has caused anxiety among the general public but even if the accident hadn't happened we would be monitoring and taking action if the government's very conservative standards are exceeded," the government's spokesman, Chief Cabinet Secretary Yukio Edano, said at a briefing.
In the first five days after the disasters struck, the Fukushima complex saw explosions and fires in four of the plant's six reactors, and the leaking of radioactive steam into the air. Since then, progress has been made cooling the active reactors and replenishing spent fuel pool, though setbacks have occurred.
An official of the U.S. Nuclear Regulatory Commission said in Washington that Units 1, 2 and 3 have all seen damage to their reactor cores, but that containment is intact. The commission's executive director, Bill Borchardt, said that "things appear to be on the verge of stabilizing."
The Vienna-based International Atomic Energy Agency said that radiation seeping into the environment is a concern and needs to be monitored. "We are still in an accident that is still in a very serious situation," said Graham Andrew, senior adviser to IAEA chief Yukiya Amano.
IAEA monitoring stations have detected radiation 1,600 times higher than normal levels -- but in an area about 12 miles from the power station, the limit of the evacuation area declared by the government last week.
Radiation at that level, while not high for a single burst, could harm health if sustained. If projected to last three days, radiation at those levels would U.S. authorities would order an evacuation as a precaution.
The levels drop dramatically the further you go from the nuclear complex. In Tokyo, about 140 miles south of the plant, levels in recent days have been higher than normal for the city but still only a third of the global average for naturally occurring background radiation.