Navy developing sub reactors than can last 40 years

From today's Breaking Defense publication
By Sydney J. Freedberg Jr.,

WASHINGTON NAVY YARD – One of the most secretive agencies in the Navy didn’t just invite reporters to its headquarters today: It offered them cookies and cake.
The agency? The Navy Nuclear Propulsion Program. The occasion? The 60th anniversary of the first submarine ever to sail under nuclear power. But there’s a lot more going on at “Naval Reactors” than nostalgia, an edible USS Nautilus, and affectionate jokes about the late Admiral Hyman Rickover, the notoriously tough founder of NR in whose honor the Navy is naming its next sub. As soon as the celebration’s done, Rickover’s heirs have to get right back to work on the design that will carry the force through the next 60 years: the Ohio Replacement.
At an estimated $95 billion for 10 ballistic missile submarines (SSBNs), the program faces daunting technological, schedule, and fiscal challenges. So what’s foremost on the mind of NR’s director, Adm. John Richardson?
“You’ve heard a couple of people mention today the ’40-year core,'” Richardson told reporters as the festivities wound down. The current Ohio subs and the nuclear Nimitz aircraft carriers require an expensive, lengthy mid-life overhaul to replace their reactor cores after 15 to 25 years of service. The new Virginia attack subs have cores designed to last the life of the sub, 33 years, although none of them is that old yet. The Ohio Replacement reactor core is supposed to last an unprecedented four decades.
“That has tremendous implications,” said Adm. Richardson, “about a $40 billion saving over the life of the program…but that’s by no means a done deal.”
Bypassing the multi-year mid-life overhaul means each submarine can spend more of its service life at sea, instead of in the shipyard. The Navy calculates the 40-year-core will allow 12 Ohio Replacement submarines to do the work of the current 14 Ohios. It will also save on maintenance funds, spare parts, and more. But it’s also making a huge bet on the core’s reliability.
“You’re talking about putting something into a reactor plant and leaving it there for 40 years at high pressure, high temperature, [and] radiation flux — all the things that come with nuclear power,” Richardson said. “Doing that safely and reliably [is] not a trivial matter. So each step, each move along that path, takes a tremendous amount of attention to detail.”