Hooked on Science: Science of nuclear meltdown

A partial meltdown of nuclear fuel rods has occurred in Japan since the devastating earthquake. What does that mean exactly? Using a few ingredients from around the house, you can see the science behind a nuclear meltdown. Parental supervision is suggested.

Materials

* Transparent container

* Five long candles

* Matches

* Water

* Clay

Instructions

STEP 1: Place a small ball of clay on the bottom of each candle and secure them in the center of the container. Each candle should be standing straight up in the center of the container.

STEP 2: Fill the container halfway with water.

STEP 3: Using the matches, light the candles and watch.

Explanation

The candles represent the uranium fuel rods and the transparent container represents the reactor pressure vessel. Typically water would cover the uranium fuel rods. The water is circulated around the rods to keep them cool. If the water isn't pumped through quickly enough, it heats up too much and starts boiling and evaporates. The exposed rods will continue to build heat and the rods melt. When this happens, radioactive materials could be released into the reactor vessel and then into the containment building. Since some water is left in the container, this is considered a partial nuclear meltdown. This greater area of air pressure pushes down on the water forcing the water into the container.

Jason Lindsey is a science outreach educator with Hooked on Science. Check out his website www.hookedonscience.org for webcasts and experiments that might get you hooked on science. Send him your science questions at jlindsey@hookedonsciencecom. More science experiments can be found at www.semisourian.com.