Friday, January 30, 2015

Nuclear reactors to last 40-plus years for largest subs ever to be built

Stew Magnuson, National Defense Magazine, Feb 2015

The Navy hopes to have the first replacement for the Ohio-class ballistic missile submarine on duty by 2031. When that vessel is launched, the onboard nuclear power plant is expected to last its entire 40-year service life.
That is seven years longer than the current reactors aboard U.S. submarines. 
“Our goal for the new submarines is to have a life-of-the-ship reactor,” said Frank G. Klotz, National Nuclear Security Administration administrator and the Department of Energy’s undersecretary of nuclear security. NNSA is responsible for developing government-owned nuclear power plants.
There are two primary reasons the NNSA is undertaking the new core design, he told reporters in November.
“It is extraordinarily important on cost because one of the largest elements of the total operational cost of a submarine over its life has been replacing the core when that has come due. It is very expensive,” he said.
“The other aspect is that when you go into the deep overhaul that is necessary to replace the core, you’re taking a submarine out of service for a long time. So if you have a life of the sub or a life of the ship core, then you avoid both cost, and you avoid both extensive downtime as you refuel the reactor,” Klotz said.
The savings could be substantial.
Olivia Volkoff, a spokeswoman for the program, said: “Eliminating the refueling through insertion of a life-of-the-ship core allows the Navy to meet the strategic deterrent mission with two fewer SSBNs and saves about $40 billion in ship acquisition and lifecycle costs over the life of the program.” 
The Virginia-class attack submarines were the first to have a core reactor designed to last the life of the vessel, which for it, is about 33 years.
The Ohio-class replacement submarines, which will carry the nation’s sea-launched nuclear missiles, will be 60 percent larger than the Virginia-class ships. 
The NNSA and the Navy are facing a tight deadline for developing the new power plant. Fiscal year 2031 is when the fifth Ohio-class SSBN retires, which will leave the Navy with a force of nine ships. If the lead replacement is not ready to take over by that date, it would leave the Navy one below its mandated requirement to have at least 10, Rear Adm. David C. Johnson, program executive officer for submarines, said in a speech last year.
It will take seven years to build the lead ship. That is an aggressive schedule given the Ohio-replacement will be the largest submarine ever built in the United States. That time frame is shorter than the previous three lead ship submarine builds: the Ohio, Seawolf and Virginia. The lead Virginia-class ship  took 86 months to build, Johnson noted.

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