The Department of Transportation picks routes for transporting hazardous radiological materials. It assesses risk based on accident rates, transit time, population density, and traffic.
For waste traveling by truck, interstate highways or connecting bypasses and beltways that avoid cities are preferred. Some shipments may go by rail or barge. No final routes have been selected for shipments to Yucca Mountain, Nev., but proposed routes pass near 109 cities of 100,000 people or more.
Spent nuclear fuel is shipped by licensed private companies and regulated by the Nuclear Regulatory Commission. Governors are notified, and once on the road, shipments are tracked by satellite, and crews must check in by phone every two hours. Shipments entering heavily populated areas must be escorted by an armed police officer in a separate vehicle or two escort vehicles with armed occupants.
Security is far tighter during transport of nuclear materials used in producing weapons. Heavily armed agents of the National Nuclear Security Administration drive convoys of armored tractors and cargo carriers and their escort vehicles. These agents, who often have served with military special forces, undergo three years of training, according to a recent court filing by NNSA official Everet Beckner. Additional agents and equipment have been added to each convoy since Sept. 11. All travel information is classified.
Such precautions do little to mollify critics, who say convoys are likely to be terrorist targets. Antitank weapons, they note, could penetrate casks of spent fuel, turning them into roadside "dirty" bombs. "One has to consider a whole range of attack scenarios," says Edward Lyman of the Nuclear Control Institute. "More than a single armed state-police car may be needed."
But Robert Jefferson, a former Sandia National Laboratory nuclear engineer and now a consultant, notes that over the years, the government has undertaken at least eight classified tests to see how well the casks would hold up under "the most likely attack modes."
One set of tests, leaked to the public, involved using armor-piercing charges against a shipping cask with walls 10 to 14 inches thick. The engineers used a demolition charge, Mr. Jefferson says, which packs more punch than those used in antitank weapons.
In the initial test, "we blew a hole in it and determined that as much as 1 percent of the contents could get out," he says. But from a clean-up and "dirty bomb" standpoint, what counts is the form the released material takes. Aerosol is the most lethal. So they ran the test again in a "big steel bottle" with filters to capture particles roughly 10 microns across or smaller. About 0.03 percent of the released material emerged in a readily dispersible aerosol form. If that were released in New York's Times Square at rush hour, "in a population that expects from 30,000 to 100,000 cancers during the next 30 years, they would have produced one-half of an additional cancer," he says.
He and other experts agree that there is no room for complacency when shipping nuclear materials.