Our plant set records in our refuel outages in 2005 and 2007 for shortest cold shutdowns. We went from 100% power down to 0% in the matter of an hour. That used to take days to do.
It really is as simple as boiling water, some plants use steam to turn the turbine, other use pressure, BWR and PWR respectively.
We are in no shortage of fuel, I've never heard anyone ever talk about running out. My plant, and most others in the U.S. are burning old soviet weapons, not because we're running out of the fresh stuff, it's just cheaper. That is the beauty of a nuclear power plant, a few trucks worth of fuel lasts in the reactor for 6 years. They divide the fuel into 3 sections, the inner sections burn out first, then after 2 years you take the inner our, and move the middle section in, and the outer section to the middle, and put in new fuel on the outside. It doesn't take much work to keep running, for the guys who man the plant during it's running, it really is a cake job. Guys like me (outage support) have all the hard work