A new government report challenges a pillar of planning for disasters at nuclear power plants, finding that people living beyond the official 10-mile evacuation zone might be so frightened by the prospect of spreading radiation that they would flee on their own, clogging roads and delaying the escape of others.
For more than 30 years, community readiness has been based on the belief that evacuation planning isn't needed beyond 10 miles. But the Government Accountability Office report found that regulators have never properly studied how many people beyond 10 miles would make their own decisions to take flight.
"Evacuation time estimates may not accurately consider the impact" of such decisions, the GAO said.
Neil Sheehan, a spokesman for the federal Nuclear Regulatory Commission, disputed the GAO's conclusions. "We disagree with the view that evacuations cannot be safely carried out," he said in an email.
The disaster at the Fukushima Dai-ichi nuclear complex in Japan two years ago has heightened worry about how well U.S. communities can respond to a major release of radiation.
When a tsunami cut off power and nuclear fuel melted, more than 150,000 people fled the Fukushima area, many from well beyond 12 miles, according to Japan's Education Ministry. U.S. officials recommended that Americans in Japan stay 50 miles back.
Under federal rules, U.S. communities practice for evacuation or other protective action by residents only within 10 miles of nuclear plants. States also lay plans to limit consumption of contaminated crops, milk and water within 50 miles.
Environmental and anti-nuclear groups have pressed federal regulators to expand planning to 25 miles for evacuation and 100 miles for contaminated food.
About 120 million Americans live within 50 miles of a nuclear power plant, according to an Associated Press analysis of census data.
Sen. Robert P. Casey Jr. (D-Pa.), one of four senators who requested the GAO study, said it suggests "we need to do more to ensure that these residents who live outside of the 10-mile radius have access to and understand evacuation procedures." He said legislation may be needed, but gave no details.