May 18, 2007: Nuclear powered warships have to have their depleted nuclear fuel replaced after 20-30 years. That's expensive, and time consuming. For example, the U.S. Nimitz class carrier USS Carl Vinson (CVN 70) entered service in 1982, but is now undergoing a three year refurbishment that will include the refueling, and a long list of upgrades. This will cost $3.1 billion. The nuclear refueling accounts for 16 percent of that. The upgrades to mechanical and electronic components will reduce crew size, and allow more space for the crew, in refurbished living quarters. All this will keep the Vinson in service until 2032.

The nuclear refueling has become obsolete. The latest SSN subs (Seawolf and Virginia) use a new reactor design that eliminates the need for the elaborate (taking apart the reactors, and part of the ship) refueling process. The next American carrier, CVN 21, will use this new technology.

But what won't go away will be the massive refurbishments. This is something that has been going on for decades, and has become more important as new technology is introduced at a more rapid rate. The Vinson work will be done in 2009.