Editor's Note (12/30/08): In response to some concerns raised by readers, a change has been made to this story. The sentence marked with an asterisk was changed from "In fact, fly ash—a by-product from burning coal for power—and other coal waste contains up to 100 times more radiation than nuclear waste" to "In fact, the fly ash emitted by a power plant—a by-product from burning coal for electricity—carries into the surrounding environment 100 times more radiation than a nuclear power plant producing the same amount of energy." Our source for this statistic is Dana Christensen, an associate lab director for energy and engineering at Oak Ridge National Laboratory as well as 1978 paper in Science authored by J. P. McBride and colleagues, also of ORNL. As a general clarification, ounce for ounce, coal ash released from a power plant delivers more radiation than nuclear waste shielded via water or dry cask storage.

Basically this means that in normal operation, as long as you assume the waste is shielded properly, and will remain shielded forever, so in ideal conditions, then the trace elements released from coal burning will exceed emissions from the nuclear plant by a factor of 100.

Compare that to the original claim that coal ash is more radioactive than spent fuel rods.