Frustration, confusion reign in nuclear crisis

As Japan struggles to contain its ongoing nuclear crisis, fear, confusion and frustration have mounted regarding the true extent of the disaster and the potential for dangerous health effects.

"They are up against a wall ... this is not just one Three Mile Island. It's effectively four," Sharon Squassoni, an expert on nuclear issues at the Center for Strategic and International Studies, told CBS' "The Early Show."

Since the last week's 9.0-magnitude earthquake and subsequent tsunami hit, authorities have been struggling to avert an environmental catastrophe at the Fukushima Dai-ichi complex, 140 miles north of Tokyo. The tsunami knocked out the backup diesel generators needed to keep nuclear fuel cool, setting off the atomic crisis.

Complete coverage: Disaster in Japan

There are six reactors at the plant. Units 1, 2 and 3, which were operating last week, shut down automatically when the quake hit. Since then, all three have been rocked by explosions. Compounding the problems, on Tuesday a fire broke out in Unit 4's fuel storage pond, an area where used nuclear fuel is kept cool, causing radioactivity to be released into the atmosphere.

Panic, confusion over Japan plant evacuation

Units 4, 5 and 6 were shut at the time of the quake, but even offline reactors have nuclear fuel -- either inside the reactors or in storage ponds -- that need to be kept cool.

On Wednesday, Japan ordered emergency workers to withdraw from the nuclear complex amid a surge in radiation, temporarily suspending efforts to cool the overheating reactors. Hours later, officials said they were preparing to send the team back in.

Radiation reality check: Risks and fears

But details of the situation were murky. Chief Cabinet Secretary Yukio Edano said the workers, who had been dousing the reactors with seawater in a frantic effort to stabilize their temperatures, had no choice but to pull back from the most dangerous areas.

"The workers cannot carry out even minimal work at the plant now," he said Wednesday morning, as smoke billowed above the crippled Fukushima Dai-ichi nuclear complex. "Because of the radiation risk we are on standby."

Pictures: Faces of the Japan crisis

Later, an official with Tokyo Electric Power, which operates the plant, said the team had withdrawn about 500 yards from the complex, but were getting ready to go back in.

However, Ryohei Shiomi, of Japan's Nuclear and Industrial Safety Agency, told CBS News in a phone interview that the plant was never completely abandoned. He would not say how many workers remained inside the Fukushima Dai-ichi plant after the government suggested an evacuation was taking place.

Video: Finding friends and family in Japan

Speaking to CBS Radio News' Lucy Craft earlier on Wednesday, a representative from Tepco, the company which runs the Fukushima plant, said all the workers were back on the job.

Hazy accounts of the crisis have left people around the country frustrated and desperate for answers.

"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 already housing people moved from nearby the plant do not have enough hot meals and basic necessities.

Pictures: U.S. relief crews in Japan

"There is both positive and negative news. I don't know what to believe," one Tokyo woman told CBS News. "Is the facility on the verge of a meltdown or not?"

American Mark Carney also wishes he knew more.

"I can read articles about, you know, 'Will the radiation reach the United States?', and 'What should you do in California?' as I'm sitting in the prefecture in which this is going on, and I'm not being told what to do."

Fears are so high, voluntary radiation exams are being administered as far as Niigata on the west coast of Japan. And Japanese nuclear authorities have a history of being less than forthcoming about the safety of their reactors, which only contributes to the confusion and distrust, reports CBS News correspondent Harry Smith.

Radiation levels had gone down by later Wednesday. The workers at the forefront of the fight -- a core team of about 180 -- had been regularly rotated in and out of the danger zone to minimize their radiation exposure, which can damage human cells.

To give some perspective on the dangers posed by the radiation, a chest X-ray emits about 1/10th of a millisievert, the unit of measurement for radiation.

Nuclear plant workers are limited to 20 millisieverts a year. One-hundred milisieverts in one dose can increase the risk of cancer, and 100 to 500 can cause bone marrow damage, leading to infection and death.

Reports say radiation levels were as high as 400 millisieverts an hour at the plant Tuesday. But they fell dramatically -- first to 11.9, then to zero-point-six.

For further perspective, in Chernobyl, among people who became sick the radiation dose ranged from 800 to 1.6 million millisieverts - much higher than what's being measured so far in Japan.

Squassoni also said the crisis was by no means as serious as the Soviet Union's 1986 Chernobyl disaster, the worst nuclear catastrophe in the history of the world. But the fact that multiple reactors are in peril put it ahead of 1979's Three Mile Island, which occurred in Pennsylvania.

Wednesday's radiation spike was apparently the result of a release of pressure that had built up in the complex's Unit 2 reactor, officials said. Steam and pressure build up in the reactors as workers try to cool the fuel rods, leading to controlled pressure releases through vents -- as well as uncontrolled explosions.

John Price, an Australia-based nuclear safety expert, 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."

Given the radiation levels, he saw few health risks for the general public so far, though he was concerned for the workers, who he said were almost certainly working in full body suits and breathing through respirators.

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.

The government has ordered some 140,000 people in the vicinity to stay indoors. A little radiation was also detected in Tokyo, triggering panic buying of food and water.

Meanwhile, the Nuclear and Industrial Safety Agency estimated that 70 percent of the rods have been damaged at the No. 1 reactor.

Japan's national news agency, Kyodo, said that 33 percent of the fuel rods at the No. 2 reactor were damaged and that the cores of both reactors were believed to have partially melted.

"We don't know the nature of the damage," said Minoru Ohgoda, spokesman for the country's nuclear safety agency. "It could be either melting, or there might be some holes in them."

Meanwhile, the outer housing of the containment vessel at the No. 4 unit erupted in flames early Wednesday, said Hajimi Motujuku, a spokesman for the plant's operator, Tokyo Electric Power Co.

Japan's nuclear safety agency said fire and smoke could no longer be seen at Unit 4, but that it was unable to confirm that the blaze had been put out.