Engineers still struggled today with Japan's crippled Fukushima Daiichi nuclear plant, and the head of the U.S. Nuclear Regulatory Commission, Gregory Jaczko, told a House subcommittee Wednesday that he would recommend evacuating people within 50 miles of the plant -- a much larger ring than the 12-13 miles (20 km) set up by the Japanese.
To those of us here who might worry, nuclear engineers and meteorologists said the U.S., including Alaska and Hawaii, is safe."We believe that secondary containment has been destroyed and there is no water in the spent fuel pool, and we believe radiation levels are extremely high," Jaczko testified to the House Energy and Power Subcommittee.But could the danger spread to American shores?
"These releases from the plant, because they're not elevated, because they're not getting up high in the atmosphere, they won't travel very far," said Kathryn Higley, director of the department of nuclear engineering at Oregon State University. "There are so many factors in our favor. Rain will knock it down. There are 5,000 miles of ocean between us and Japan. It will be diluted, it will mix with sea spray, long before it gets remotely close to us."
Nevertheless, the Environmental Protection Agency announced Tuesday that it was adding several monitors to its RadNet system of radiation detectors. The small monitors are scattered around the country -- there are 12 in California and two in Oregon, for instance -- but the EPA said, "in an abundance of caution," it would add two new ones in Hawaii, two in Guam, and three in Alaska.
Even as it announced the detectors, the agency tried to be reassuring: "As the Nuclear Regulatory Commission has said, we do not expect to see radiation at harmful levels reaching the U.S. from damaged Japanese nuclear power plants."
The high-altitude winds over Japan are primarily out of the west -- good news for Japan in a worst-case scenario, if there were a large release of radiation into the air.
And if there is a worst case, with radioactive particles carried long-distance by upper-level winds?
In that case, "we will get some fallout on the West Coast 2-3 days after its release in Japan," said Edward Morse, a nuclear engineer at the University of California, Berkeley, in an e-mail to ABC News. "The levels will not be threatening to life and health but they will be observable."
At Texas A&M University, Prof. Ken Bowman and graduate student Cameron Homeyer put together a computer projection showing that if any radiation from the March 14 explosion at the plant reached altitudes of 4-5 miles (6 km), it might pass over northern Alaska on Friday. But Bowman said his model was not designed to show the intensity of any plume getting that far.
"If any radiation were to make it here, it would be merely background levels," said Jere Jenkins, the director of Radiation Laboratories at Purdue University in West Lafayette, Ind. "Nothing for people on the West Coast or people in the United States to be concerned about."
Higley said she has been spending a lot of time over the last few days urging calm.
"We have monitoring capability here in the U.S. that is extraordinarily sensitive. We can detect radiation that is like a hundred-thousandth of what you get from a regular X-ray, and we don't expect to see even that.
"For the stuff to travel, it has to be picked up by the wind," she said, "higher-level winds that have global distribution. And that's just not happening. This is a little like a campfire -- the smoke is all near the ground."
