The nuclear reactors have an endurance of ~25 years. (Not limited by amount of uranium, but by build-up of undesirable elements). After that, they need to be re

The nuclear reactors have an endurance of ~25 years. (Not limited by amount of uranium, but by build-up of undesirable elements). After that, they need to be refueled, and that is done as a part of a complex mid-life refit that takes over 3 years. The construction cadence of the Nimitz class was set with the idea that starting from '98, all the carriers would be refueled and refitted in turn, so that one is always at the yard. Right now, that carrier is USS Abraham Lincoln (CVN-72), which entered the dock in March 2013, and still remains there.