People living within 10 miles of the Palo Verde Nuclear Generating Station west of Phoenix are well-aware they are in the evacuation zone of Arizona's only nuclear power plant.

Those 11,545 residents get an annual calendar from the plant's owners with instructions on what to do in the remote event of a disaster.

Palo Verde Nuclear Generating Station

Since the March nuclear meltdown in Japan, when an earthquake and tsunami damaged a plant and released untold amounts of radiation, industry watchdogs have scrutinized U.S. nuclear-emergency plans, especially since the U.S. Nuclear Regulatory Commission advised U.S. citizens within 50 miles of the Japanese plant to evacuate.

That perimeter led observers to question whether the NRC-imposed 10-mile evacuation zones for plants in the U.S. are sufficient.

Federal emergency plans for U.S. nuclear reactors, laid out in 1978, have a 10-mile perimeter divided into segments that could be evacuated. If radiation escaped from a plant, it's likely all people 2 miles around the plant and 5 miles downwind would immediately be ordered to leave, while weather conditions and the severity of the radiation release would determine who else would need to be evacuated from the 10-mile zone.

While the zone can be expanded, any evacuation beyond 10 miles would be improvised.

The difference between evacuating a narrow 10-mile perimeter and one extending to 50 miles around Palo Verde would be moving 11,545 people, estimated to take about three hours, or relocating nearly 2 million people. Most of the evacuation zone around Palo Verde is empty desert west of Buckeye, while the larger radius extends as far as downtown Phoenix, and evacuating it essentially could amount to a national crisis requiring military assistance.

U.S. Nuclear Regulatory Commission officials said they advised the evacuation of U.S. citizens within 50 miles of the Japanese power plant March 16 out of extreme caution because, five days after the earthquake and tsunami, they didn't have enough information about the damage and how much radiation was being released.

Few doubt the safety of Palo Verde, which is far from earthquake fault lines and unlikely to suffer a devastating natural disaster.

But the unimaginable happened at Japan's Fukushima Dai-ichi plant, spurring leading U.S. scientists to ask if emergency plans are sufficient, especially now that many more people are living closer to reactors than 25 years ago. Only about 1,500 people lived within 10 miles of Palo Verde when it opened in the mid-1980s. Almost eight times as many live there now.

Palo Verde officials say chances of the kind of nuclear disaster that occurred in Japan are extremely remote. They also say that U.S. reactors, especially Palo Verde, are better protected and have more reliable backup safety systems than Fukushima, and that the nuclear industry here has practiced for a disaster more than Japan.

Officials at Palo Verde also said they are more capable of tracking radiation leakages and providing accurate details for specific evacuations, unlike in Japan, where confusion about the severity of the meltdown led to a broad evacuation.

The watchdog group Union of Concerned Scientists recommended in the wake of the Fukushima disaster that the "arbitrary" 10-mile evacuation zone be reviewed to determine if a wider swath of residents should be prepared to evacuate. Citing the multiple-reactor failure in Japan, they believe U.S. emergency measures underestimate the potential extent of radiation contamination and a possible evacuation.

The group also made dozens of other recommendations to improve U.S. plants, such as beefing up plans in case of a power blackout, like in Japan, and moving used radioactive fuel to dry, concrete storage containers and out of pools of water as soon as possible.

The NRC is evaluating many aspects of U.S. operations in light of Fukushima, but officials said they still believe the 10-mile evacuation zones are adequate.

Union of Concerned Scientists officials said they will continue to press for a review of evacuation zones.

Preparedness drills

In the event of an accident at Palo Verde, sirens around the plant would be the first warning to nearby residents that radiation might be escaping into the air.

A continuous, three-minute wail signals that people should head indoors and listen to the television or radio for advisories.

Sirens don't necessarily mean an evacuation is under way.

If the risk of radiation exposure is low, people might be told to stay indoors with windows and doors closed. And if an evacuation is ordered, it might apply to only some sectors of the evacuation zone.

Sheriff's deputies would direct traffic and patrol empty neighborhoods. Schoolchildren would be evacuated to a safe location. High schools in Goodyear, Buckeye and Wickenburg would serve as emergency centers. Evacuees would not be sent to distant communities like Tucson or Flagstaff because dangerous radiation is unlikely to spread very far, and the deluge of people could overwhelm smaller cities, officials said.

Radiation from a single-reactor leak would likely not spread beyond the 10-mile perimeter unless there were strong winds or the damage was extensive. The U.S. has 29 single-reactor sites, 33 double-reactor sites, and three triple-reactor sites like Palo Verde.

Fukushima had six reactors, three of which were operating when disaster struck. A fourth had used fuel that needed to be kept cool with water.

Palo Verde officials said they are well-prepared to expand a 10-mile evacuation in the extremely rare chance that was needed.

In Japan, one of the biggest problems in ordering evacuations was calculating how much radiation was escaping, critical for determining danger levels. Damage to the Fukushima reactors was so severe and radiation so intense, workers could not immediately enter key areas of the plant to see if the radioactive fuel was still underwater, or if it was uncovered and therefore releasing large amounts of radiation.

Officials had to deal with widespread confusion for several days over how much damage the reactors sustained and how much radiation was potentially being released.

That wouldn't be the case at Palo Verde, officials say, because of its extensive electronic monitoring system.

While workers at the Arizona plant might have to contend with high radiation levels that could cause burns, illness or even death, the primary health concern for citizens outside the plant would be developing cancer over time from exposure.

Only a complete breach of the concrete and steel containment structures at Palo Verde could expose those nearby to lethal doses of radiation, and even industry critics say that scenario is extremely unlikely.

If the plant loses cooling water and uranium fuel is exposed to air, it can create fission byproducts. Those posing the greatest medical concern are radioactive iodine and cesium, said Kenneth Mossman, a professor of health physics at Arizona State University. Iodine, which can be inhaled, is the biggest threat for people near the plant because it accumulates in the thyroid gland, where it can cause cancer. It can be blocked by potassium iodide pills if taken soon after exposure, Mossman said.

The state keeps a supply of pills that could treat 32,900 adults and smaller liquid doses for about 2,000 infants and children.

Cesium, a solid that usually falls to the ground, can contaminate food crops and animal feed, and can end up in milk and the meat of animals that ingest it. Officials would monitor food and livestock within a 50-mile perimeter to prevent contaminated products from going to market.

No one would be allowed to return to an evacuated area until contamination levels were safe. In Japan, people still are not allowed within 12 miles of the devastated plant.

Nuclear-power industry experts expect to learn a lot about dealing with a major radiation release by studying the recovery in Japan.

A special NRC task force formed after Fukushima says radiation-response plans and reopening evacuation zones "remain largely conceptual and are rarely practiced."

It has recommended the U.S. industry improve those plans because of the trouble Japan has had cleaning up, moving people back into the area and tracking contaminated food.

Critical voices

Some nuclear-industry experts said the Fukushima disaster exposed weaknesses in the U.S. emergency plans for nuclear plants, particularly for managing a large-scale evacuation.

The Washington, D.C.-based Union of Concerned Scientists, which advocates for increased safety and more rigorous regulatory oversight at nuclear facilities, contends that a wider evacuation is plausible, given what happened in Japan, and that U.S. plants should practice for radiation releases involving multiple reactors when they conduct routine emergency drills.

The group says that planning only for a 10-mile evacuation zone around reactors is inadequate because it doesn't take into consideration the possibility of having to evacuate a larger area and the consequences of civil disorder that might ensue from gridlocked roads in the scramble to flee.

They believe a bigger evacuation like that advised for U.S. citizens in Japan could cause mayhem in a metro area like Phoenix and could lead to deaths as panicking people try to escape down congested roads. Emergency responders should be prepared to handle a broader evacuation, rather than preparing only for the small, relatively easy 10-mile one, officials from the Union of Concerned Scientists said.

And because a wider evacuation might be necessary, emergency planners should also consider giving people within a broader perimeter of nuclear-power plants the same information and instructions as those living in the 10-mile zone.

The group also argued that emergency plans wrongly assume that a severe problem at a nuclear facility would not be accompanied by other emergencies. If a severe earthquake or other event damaged a nuclear plant, it also would likely damage surrounding infrastructure and any help might be spread thin throughout the region, the watchdog group said.

"The scale of the overlapping disasters in Japan overwhelmed those resources," its report said.

David Lochbaum, director of the Nuclear Safety Project for the Union of Concerned Scientists, said the NRC is assuming that a disaster of the same scale as Japan's will not occur in the U.S.

"There may be a situation in the U.S., where, like in Japan, you don't have all the information (about the state of the plant and amount of radiation leaking)," he said. "They claim they would never get into that box. (That assumption) seems somewhat flimsy."

U.S. nuclear officials assume they would be able to assess the damage to a plant and calculate how much radiation is being released, he says, but Japanese officials were not able to do that as the disaster unfolded.

Lochbaum said the nuclear industry's assertions that any emergency would be unlikely to expose people nearby to lethal amounts of radiation are correct but that emergency plans must take more into consideration.

"It is not likely there would be an event that would cause someone to die within 30 days (of the radiation exposure)," he said. But he added that "one of the concerns is that if you order an evacuation, people will die. People in nursing homes and others that need special care that may need to be moved may not (survive) the journey.

"They need to look at the sites, what is the population, infrastructure, and if it is reasonable that you could evacuate those people affected in time," Lochbaum said. "You need to test that you can go beyond that evacuation line, wherever it is that you design it."

Reassurances

Regulators and officials at Palo Verde say the plant is safe from any event that would cause a notable radiation leak and that the emergency plans are adequate should such an event occur.

Every two years, the plant's operator, Arizona Public Service Co., along with the state, county, Red Cross, Department of Agriculture, Department of Health and law enforcement practice for an extreme accident.

They simulate how much radiation would be released and where the radiation plume would go under certain weather conditions.

Officials said it is reassuring that even simulating a large radiation release requires imagining an extremely unlikely natural disaster coupled with unlikely mechanical failures at the plant, just to concoct a situation that would trigger evacuation plans.

"It is virtually impossible to (test) the things we need just to walk through the emergency-response process," said Bill Wolfe, a program coordinator with the Arizona Division of Emergency Management.

It's also reassuring, officials said, that the plant operators often are able to quickly mitigate simulated radiation releases during practice drills.

"There are times they beat us," said Randy Edington, chief nuclear officer for APS. "The plant operators simulate repairs to the reactor faster than we are (simulating) breaking it."

One of the key problems in Japan, the lack of information readily available about how much radiation was escaping from the damaged rectors, would be unlikely, even in a severe natural disaster at Palo Verde, officials said, because the plant has a variety of ways to monitor the reactors.

There are remote-controlled cameras to assess damage and monitors that detect radiation from sites around the plant, plus aircraft could be deployed to take readings.

The data would be analyzed by emergency responders at a new, $16 million emergency center about 20 miles east of Palo Verde. Federal regulations require emergency centers to be more than 10 miles from the reactors but fewer than 25 miles.

"We would be able to understand what the plant is going through," said Monica Ray, emergency-preparedness director at Palo Verde.

The emergency center's capabilities include live video diagrams of the nuclear reactors, their power output, temperatures, cooling water flow and other data.

Besides the direct video feeds from Palo Verde, the center has sophisticated wind- and weather-tracking capabilities, and an expansive communications network.

It also has two backup diesel generators and four hours of backup battery power in case a natural disaster like an earthquake damaged not only the nuclear reactors but also the surrounding infrastructure.

It is highly unlikely any of the center's technology will ever be put to use because the chances of a radiation release large enough to trigger an evacuation is slim, Wolfe said.

Even so, the NRC has recommended that plants develop new ways to estimate radiation releases if multiple reactors are damaged.

Even if radiation were released from Palo Verde, the primary concern would be for workers at the plant trying to control the problem, Mossman said.

"Frankly, there is no need to evacuate anybody" during events that release small amounts of radiation, he said. "The doses emitted are so small they don't produce any measurable health effects. But that doesn't help people in the general populace. They need to feel they can do something and that the government is doing something to ameliorate the situation."

Mossman said ordering an evacuation is a difficult decision, balancing the harm people could cause by crowding the highways against the harm from relatively small exposures to radiation.

He said the NRC decision to call a 50-mile evacuation of U.S. citizens in Japan was prudent, and doesn't represent an inconsistency in emergency planning, only because officials were acting on scant data from the power plant.

"Had they had better information available to them, the decision might not have been made," he said. "The driver is fear and anxiety, which is what we need to control. That means full disclosure, which (Tokyo Electric Power Co.) and the government in Japan did not do."

Emergency responders need to ensure the public trusts what they are saying during a crisis and that their messages are clear, because the public fear of radiation can be intense, Wolfe said.

"The public has been taught to fear radiation since Hiroshima and Nagasaki," Wolfe said.

What's next

The Union of Concerned Scientists will continue to present information and push its case over evacuation zones to the NRC, Lochbaum said.

"They seem pretty happy with the 10-mile zone," he said. "Given the recommendation to evacuate up to 50 miles after Fukushima, there is an apparent disconnect. Hopefully (a change) is still on the table. We can still present our views and see what they are thinking."

He said expanding evacuation zones is not a "clear and present danger," but something that should be addressed soon.

"We have time to implement this, but at the same time, it shouldn't be delayed indefinitely," he said.

The NRC task force formed after Fukushima recently presented ideas to make U.S. reactors safer in light of what happened in Japan.

The task force didn't recommend changing the 10-mile evacuation zone around U.S. reactors, but did suggest developing computer models that can calculate the expected radiation doses in the area if multiple reactors or fuel pools are affected, like in Japan. The task force's report said the 10-mile planning zones provide a "substantial base" that could be expanded if needed.

Whether or not new information causes regulators to change the evacuation guidelines, several area residents said the Fukushima disaster did little to stoke fears in the West Valley.

"It's no big deal," said Daniel Chavez, 23, as he worked at the TravelCenters of America truck stop in Tonopah, on Interstate 10, just a few miles from Palo Verde.

"You would think that it would, but no. I didn't hear anything about it with the locals out here," said Chavez, whose Buckeye home is farther from the plant, but still well within 50 miles.

While the population has boomed around Palo Verde, surveys typically show that people who live near reactors are supportive of nuclear power.

A J.D. Power and Associates utility-customer survey released in July showed that 70 percent of people who say they live within 50 miles of a nuclear reactor support nuclear power.