The Effects of a Nuclear Meltdown

The heat produced by a nuclear reactor is the result of a carefully controlled process. Moderating materials act as a throttle for radioactivity produced by concentrated uranium, and coolant manages the reactor's temperature. If the coolant and moderators fail, uranium fuel temperatures will soar to thousands of degrees. The reactor core will become a hot blob of metal and concrete, melting through everything it touches.

Explosion

• Nuclear reactor fuel is not as purified as nuclear bomb materials are, so it won't explode in that manner. However, the hot reactor can explode from built-up superheated gases and steam. In April, 1986, the Chernobyl reactor in the Ukraine exploded in this fashion. It blew the 1,000-ton lid off the reactor with an explosive force equal to 1 ton of TNT.

Fallout

• After a serious explosion, smoke and ash containing radioactive particles may escape into the outside air. The particles will drift downwind, eventually coming to the ground as fallout. The fallout can contaminate many square miles surrounding the reactor. Radioactive materials in the fallout include iodine, uranium and traces of other elements.

Containment Breach

• In a nuclear power plant, the reactor sits in a large concrete containment building. Its purpose is to prevent radioactivity from escaping the reactor in case of emergencies. During a meltdown, however, the molten reactor is hot enough to penetrate the floor of the containment building.

China Syndrome

• In a complete meltdown, after breaching the bottom of the containment building, the hot material may continue to melt its way into the ground. In 1971, physicist Ralph Lapp coined the term "China Syndrome" to describe the radioactive mass melting its way completely through the earth. Realistically, the ground would absorb its heat after it melted a few meters. Even during the worst nuclear accidents, this has never happened.