Ahh..Nimitz was refueled from 29 May 1998 to 28 Jun 2001. So she was 25 years old when her RCOH began. Wow.. great engineering.
Well, I go by commission date, which was 1975. So 1975 to 1998 makes 23 years in commission. If you go by launch date, then yes, 25+ years.
I looked back at this, and popeye is exactly right. Apparently upgrades to the core design DID make it into the first three. Their original core design was older and would have been only 13 years...but the advances were made before they fueled Nimitz the first time and she got the better cores, as did all the rest.
I will go back and fix that in my original post.
So far, the RCOHs have gone like this:
USS Nimitz, CVN-68, RCHO 1998-2001 (Commisionmed 1975) 23 years
USS Dwight Eisenhower, CVN-69, RCOH 2001-2005 (Commissioned 1977) 24 Years
USS Carl Vinson, CVN-70, RCOH 2005-2008 (Commissioned 1982) 23 years
USS Theodroe Roosevelt, CVN-71, RCOH 2009-2013 (Commissioned 1986) 23 years
USS Abraham Lincoln, CVN-72, RCOH 2013- (Commissioned 1989) 24 years
Four complete...the fifth underway.