Refueling a nuclear submarine is quite a bit different than refueling a commercial reactor. In a commercial reactor, spent-fuel rods are removed and replaced by fresh uranium fuel. In a sub, the entire hull section containing the nuclear reactor is cut out and a new reactor section is welded back in.
The U.S. has 92 of these hull sections awaiting deep burial. There will be at least that many again as most subs are approaching decommissioning.
These cut-out hull sections are quite impressive: they are four to five times taller and wider than the heavyhaul trucks that transport them.
The DOE says it's considering other disposal options, such as shallow burial at federal or private facilities, but that's exactly how the sections are buried now. The hull sections are sitting under 40 feet of dirt at Hanford Nuclear Reservation in Richland, Washington, but expect these to move to geologic repositories as soon as possible.
(I've always wondered why the size of the entrance tunnel in repositories is so large, and now I know.)
I suppose the DOE was emptying its Bad News file because it announced at the same time that portions of commercial-reactor cores are going to mountains too. That answers the question of where Three Mile Island's molten reactor core's going.
[Source: Federal Register, May 11, 2005, Volume 70, Number 90, Page 24775-24778]
May 16, 2005