Good Question: What Is A Nuclear Meltdown?

(CBS 5) – It has become one of the biggest concerns as Japan's nuclear crisis continues. Marjorie in Berkeley asked this Good Question: Exactly what is a nuclear meltdown? What are the long-term effects?

ANSWER: According to UC Berkeley nuclear engineer Donald Olander, a nuclear meltdown occurs when fuel rods begin to decay uncontrollably because of a lack of coolant or water to protect the pressure vessel. Temperatures can get to 3800 degrees and actually melt the vessel, dropping molten metal and fissionable material into a containment room.

(Copyright 2011 by CBS San Francisco. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)