Nuclear nightmare? The U.S. depends on 103 nuclear reactors for energy. Are they sitting ducks for terrorists? (Nuclear Power/Radiation).

UNDER THE cover of darkness, three masked saboteurs scale the barbed-wire fence that fortifies the Waterford 3 nuclear plant in Taft, Louisiana. The armed intruders disable surveillance cameras, sneak past security guards, and slip inside the plant's control room. Within seconds, they shut down the plant's vital cooling system--and unleash a nuclear meltdown.

Scared? The scene is fictional--based on a simulated terrorist attack staged in 1999 by the Nuclear Regulatory Commission (NRC). The bad news: Waterford is one of more than 37 (out of 63) operating U.S. nuclear power plants that have failed such mock drills in the past decade. "This is a troubling indication that security measures may be inadequate-especially after September 11," says physicist Edwin Lyman at the Nuclear Control Institute in Washington, D.C.

Since September 11, however, the NRC has worked closely with the FBI and local law enforcement agencies to beef up security at U.S. nuclear power stations. "Appropriate steps have been taken to protect the plants from attack by land, sea, and air," says NRC spokesman Victor Dricks. What exactly are nuclear power plants, and are they really safe from terrorist attacks?

FISSION FRENZY

Twenty percent of all electricity used in the U.S. comes from nuclear plants around the nation. Nuclear power's main appeal: It generates massive amounts of energy from scant amounts of fuel. Pound for pound, nuclear fuel, produced from isotopes (varying atomic forms) of the element uranium, "generates one million times more energy than coal," says University of Texas physicist Rory Coker. In fact, one pound of nuclear fuel churns out nearly 52 megawatt hours of electricity--enough juice, for example, to light up every home in Detroit, Michigan, for one week. It would take six tons of coal to generate the same amount of power.

How can a single tiny pellet of uranium spawn so much energy? Amazingly, the massive power supply derives from the invisible nucleus (center) of an atom of uranium, where a nuclear reaction--also called nuclear fission--takes place. Each atom houses positively charged protons and neutrally charged neutrons. To trigger a nuclear reaction inside a reactor, a speeding neutron collides with the nucleus of a uranium atom. The collision produces two smaller uranium nuclei and ejects more speeding neutrons, which collide with more nuclei, explains Coker (see diagram).

The chain reaction is called exothermic, because it releases heat energy--almost 200 million times more than a normal chemical reaction. In fact, nuclear reactions generate so much heat that power plants demand giant cooling systems to prevent the uranium containers (fuel rods) from overheating or melting down. U.S. power plants are equipped with backup cooling systems that are activated if primary systems fail--and even those systems have emergency standbys ready to kick in. "There is a backup for everything," Coker says.

LETHAL RAYS

But nuclear power has a downside: Along with heat energy, a nuclear reaction releases radiation, potentially life-harming high-energy rays. A lethal dose of radiation contains the same kinetic (moving) energy as a bullet fired from a rifle, explains Coker: "It knocks apart molecules in your cells--and if you disrupt enough cells, you can die."

Perhaps the most startling example of radiation's deadly effects--and scientists' textbook case for research--is the world's worst nuclear accident: Chernobyl. In 1986, an explosion at the Chernobyl nuclear power station outside Pripyat, Ukraine, destroyed the plant's reactor and spewed an estimated 100,000 to 150,000 curies, or units of radiation, into the air. Thirty-one deaths are directly attributed to the explosion; more than 200,000 residents have been permanently displaced from their homes. Scientists predict radiation from Chernobyl will linger in the air, soil, and water for up to 300 years.

Long-term health effects of Chernobyl are still being documented, but the United Nations reports that more than 1,800 children have contracted radiation-induced cancer of the thyroid, a neck gland that controls metabolism.

Is the U.S. equipped to handle a similar radiation leak? Last December, the NRC earmarked $800,000 to distribute the over-the-counter drug potassium iodide (chemical symbol KI) to 31 states with nuclear power plants. The drug has been shown to prevent thyroid cancer if taken before or immediately upon radiation exposure. The NRC also claims to have detailed evacuation plans for residents within 6 km (10 mi) of nuclear plants.

BUILT TOUGH

Fortunately, nuclear power plants in the United States are far safer than Chernobyl. For example, U.S. nuclear plants are built with steel and concrete containment buildings, dome-shaped structures engineered to contain radiation leakage and protect a reactor from earthquakes, hurricanes, even small-plane collisions (see diagram).

The NRC won't disclose security measures taken to prevent terrorism, but since September 11 the organization asserts that nuclear power plants are adequately protected. Says Melanie Lyons, spokeswoman for the Nuclear Energy Institute: "We are very well-equipped for a terrorist attack."

NUCLEAR INSECURITY: ARE POWER PLANTS AT RISK?

Nearly half of the 63 operating nuclear power plants in the U.S. have failed mock terrorist attacks against them. Had these assaults been real, they might have resulted in a radiation release greater than the 1986 Chernobyl accident. Below is a diagram of a generic nuclear power plant, depicting potential threats:

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Lesson Plans

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Cross-Curricular Connection

Geography: Research nuclear power usage throughout the world. Which nations are most dependent on nuclear power for electricity?

Did You Know?

* The over-the-counter drug potassium iodide (KI) prevents thyroid cancer by saturating the thyroid with iodide. This prevents the neck gland from absorbing radioactive iodide, a byproduct produced during a nuclear reaction. KI pills proved effective in blocking thyroid cancer when given to people within hours of the 1986 Chernobyl nuclear plant explosion.

* According to the International Atomic Energy Agency, there were 438 nuclear power plants operating worldwide in 2000. Thirty-three nuclear power plants are now under construction.

* In 1979, equipment failure and human error at the Three Mile Island Nuclear Power Plant in Pennsylvania resulted in the worst nuclear accident in U.S. history.

National Science Education Standards

Grades 5-8: transfer of energy * risks and benefits * science and technology in society

Grades 9-12: structure of atoms * structure and properties of matter * chemical reactions * conservation of energy and the increase in disorder * natural and human-induced hazards * science and technology in local, national, and global challenges

Resources

Dictionary of Science by Neil Ardley, Dorling Kindersley, 1994, pp 38-41

The Way Things Work by David Macaulay, Houghton Mifflin Company, 1998, pp 172-179

"Potassium Iodide as a Household Name" by Randal C. Archibold, The New York Times, January 21, 2002

Directions: Match the word in the left column with the correct phrase
in the right column.

1. isotopes           a. positively charged particles
2. uranium            b. units of radiation
3. potassium iodide   c. center of atom
4. curies             d. nuclear reaction
5. nucleus            e. nuclear fuel-producing element
6. protons            f. drug to prevent thyroid cancer
7. neutrons           g. neutrally charged particles
8. nuclear fission    h. varying atomic forms

ANSWERS

Nuclear Nightmare

1. h 2. e 3. f 4. b 5. c 6. a 7. g 8. d