The head of the National Nuclear Security Administration’s (NNSA) naval reactors program suggested Wednesday that the use of highly enriched uranium (HEU) for naval propulsion offers a significant advantage over the conversion of naval reactors to low-enriched uranium – indicating that the U.S. Navy’s longstanding preference for HEU is unlikely to change.
Admiral James Caldwell Jr., NNSA’s deputy administrator for naval reactors, said at a Senate Appropriations Energy and Water Subcommittee hearing that “success would not be guaranteed” in an LEU-based system. “It’s quite a leap to go forward,” he said, because it would involve “essentially adding less energy to the core.”
Advocates for global HEU minimization have pushed the U.S. Navy to consider the feasibility of converting naval reactors to LEU. The non-governmental Fissile Materials Working Group, for one, released a report in 2015 recommending research and development toward that goal.
The Nuclear Threat Initiative last year made similar recommendations in a paper, while acknowledging that conversion of naval reactors would require development of new reactors and new fuels. Still, NTI pointed to the French Navy’s conversion of its fleet to LEU as an example.
The U.S. Navy, meanwhile, has previously concluded in reports to Congress that adopting the LEU system would create disadvantages for its fleet.
Caldwell said during the hearing that the result of such a conversion would be “less endurance, less energy to use for anything on the ship, you would have to probably refuel it more frequently, you would take it offline . . . you might actually have to build more submarines so that you could maintain the required presence that you need forward.”
HEU cores in naval reactors last for the life of the ship, he noted. Development of LEU cores would take roughly $1 billion over 10 to 15 years, he said, and would also require development of an advanced fuel system.
The White House has requested $13.9 billion in funding for the NNSA in fiscal 2018, of which $1.5 billion would go toward naval nuclear propulsion work – 4.2 percent above the currently enacted $1.4 billion. This would fund the development of reactor technology and operation of reactors in nuclear-powered submarines and aircraft carriers, among other related work.