Spent Fuel Decay
The spent fuel removed from the reactors continues to release heat and is still radioactive. It is, for those reasons, that the fuel is initialy stored underwater in the spent fuel storage pools. The U.S. Department of Energy has provided graphs illustrating:
Typically fuel will remain in a reactor for 33,000 - 50,000 Megawatt-Days per Metric Tonne Uranium (MwD/MTU)
The graphs are provided below. I will provide more explanation in the future.
Graphics courtesy USDOE
Copyright © 1996-2006. The Virtual Nuclear Tourist. All rights reserved. Revised: December 21, 2005.