a pound of highly enriched uranium as used to power a nuclear submarine or nuclear aircraft carrier is equal to something on the order of a million gallons of gasoline. When you consider that a pound of uranium is smaller than a baseball, and a million gallons of gasoline would fill a cube 50 feet per side (50 feet is as tall as a five-story building), you can get an idea of the amount of energy available in just a little bit of U-235.