Originally Posted by
KenV
The main advantage of the nuke plants in US carriers is that the tankage used to store ship's propulsion fuel can instead be used to store aircraft fuel. They also allow the carrier to steam at sustained high speed for long distances to quickly arrive at a distant trouble spot without resorting to refueling enroute and arriving there ready to generate a large number of aircraft sorties.
Well that's the idea. But in practice the carrier has to hang around for its escorting fleet (it's a bit vulnerable without it), and runs out of food and aviation fuel anyway.
There's a big trade off between the size of a nuke plant and the size of a gas turbine plant. A nuke plant is quite large, with quite a large steam section, large wet turbines. Gas turbines are quite small and compact and lightweight, leaves a lot of room for fuel which is anyway the same stuff as the aircraft are using, or can be. So no need for separate fuel bunkerage. RN helos run on marine diesel.
If the carrier has to regularly RAS for food and fuel, it may just as well take on more fuel to move the ship too. That was the RN's conclusion. I recall a lot of discussion as to whether the new carriers should be nuclear powered, but it just didn't seem to be worth it. About the only thing it brings is the ability to run away jolly quickly for a long time, leaving everyone else behind.
However if you're prepared to let the carrier operate more independently of an escorting fleet then the long legs of a nuke does help. The newer USN carriers are larger, and have a lot more storage, probably for more of this type of operation.