The consequence of an aircraft’s slamming into a nuclear reactor would not be a nuclear explosion. It is physically impossible for the uranium used in U.S. power plants, which typically is less than 5 percent pure, to be fashioned into a Hiroshima-type bomb: nuclear bombs contain uranium that is closer to 90 percent pure. The real danger of a terror attack is the release of radioactive contaminants. Even in that case, scenarios of mass deaths by radiation sickness are probably overdrawn. Only 30 people died of radiation exposure after the 1986 explosion at the nuclear power station in Chernobyl, the worst accidental release of radiation in history; through 1999, the United Nations found, the breach caused 1,800 cases of thyroid cancer. Not a single identifiable death resulted from the 1979 accident at Three Mile Island. Radiation exposure can be managed by evacuation, and radiation sickness (as well as many of the subsequent cancers) can be treated. The problem is that evacuation–which could cover hundreds of square miles of densely populated suburbs and cities in the United States–would be, for all practical purposes, permanent: Chernobyl rendered more than 1,000 square miles unsafe for human life for more than 100 years. Might the accidental or intentional crash of an aircraft into a nuclear power plant–whether one built to withstand such a disaster or not–precipitate that? There have been no tests of whether even those plants with containment domes like Three Mile Island’s would actually stand up to a crash. The NRC now admits that the agency “could not exclude the possibility” of a radiation release “that could impact public safety.”
Terrorists could also target the storage facilities for spent nuclear fuel, which is kept in special pools on site at most plants. (Permanent storage, probably at a Nevada underground facility, remains years away.) The spent fuel rods are typically stored in barrels beneath 30 feet of water. The water absorbs radiation and keeps the fuel from overheating; a large plane crashing into the pool could dis-place or evaporate enough water to leave the rods exposed. The resulting buildup of heat would trigger a large release of radiation. The storage pools do not have hardened roofs. Their greatest protection is probably their size: much smaller than the reactor domes, they would represent a difficult target.
In the aftermath of Sept. 11, the FAA circulated an advisory “strongly urging” private pilots to steer clear of nuclear power plants (as well as conventional power plants, dams and refineries). In at least a few cases, military jets were scrambled to chase away private planes that wandered too close, although there’s no evidence any posed a threat. But saboteurs would not need an airplane. A large truck bomb driven past security could breach the containment vessel or spent fuel storage, too. If terrorists with nuclear training took over the controls of a reactor, they could remove its coolant, causing the fuel to overheat. The zirconium cladding on the fuel rods combusts explosively at 2,000 degrees Fahrenheit, a temperature that fissioning uranium would easily reach without coolant. Current regulations, says Daniel Hirsch, president of the nuclear watchdog group Committee to Bridge the Gap, require nuclear plants to be secure against ground-based attacks by “several” people (not a platoon-size force like the one that took over four planes on Sept. 11) and against truck bombs significantly smaller than the one that Timothy McVeigh used against the federal building in Oklahoma City.
National Guard troops were deployed at reactor sites in some states after Sept. 11, and the Coast Guard is patrolling nearby waterways. Paul Leventhal, president of the Nuclear Control Institute, is calling for plants to be guarded by antiaircraft batteries and a permanent military presence capable of repelling an assault by 200 armed terrorists. Last week France announced that it was surrounding two of its nuclear facilities with antiaircraft missiles.
FIRST STEPS: Tighten plant security, including military presence and no-flight zones. Ship spent fuel to more secure sites. Rerun employee-background checks.
