All US aircraft carriers and subs are nuclear powered
With family members that have worked / continue to work on nuclear powered ships, I’m surprised how little is known about them.
America’s Navy the Unsung Heros of Nuclear Energy
The United States has over 200 nuclear reactors producing power [in 2014]. You might be aware of the hundred or so commercial nuclear power reactors that produce just under 20% of our electricity. But there are another hundred nuclear reactors that power 86 submarines and aircraft carriers, producing electricity, heat, fresh water and propulsion.
The Nuclear Navy has logged over 5,400 reactor years [in 2014] of accident-free operations and travelled over 130 million miles on nuclear energy, enough to circle the earth 3,200 times. The nuclear reactors can run for many, many years without refueling. They operate all over the world, sometimes in hostile environments, with no maintenance support except their own crew. These reactors can ramp up from zero to full power in minutes, as fast as any natural gas-fired plant.
Nuclear Powered Ships
A marine reactor was used to supply power (1.5 MWe) to a US Antarctic base for ten years to 1972, testing the feasibility of such air-portable units for remote locations.
In the 1970s Westinghouse in alliance with Newport News shipyard developed an Offshore Power Systems (OPS) concept, with series production envisaged at Jacksonville, Florida. In 1972 two 1210 MWe units were ordered by utility PSEG for offshore Atlantic City or Brigantine, New Jersey, but the order was cancelled in 1978. By the time NRC approval was granted in 1982 for building up to eight plants, there were no customers and Westinghouse closed down its OPS division.
The head of the large Chinese shipping company Cosco suggested in December 2009 that container ships should be powered by nuclear reactors in order to reduce greenhouse gas emissions from shipping. He said that Cosco was in talks with China’s nuclear authority to develop nuclear powered freight vessels. However, in 2011 Cosco aborted the study after three years, following the Fukushima accident.
In response to its members’ interest in nuclear propulsion, Lloyd’s Register has rewritten its ‘rules’ for nuclear ships, which concern the integration of a reactor certified by a land-based regulator with the rest of the ship. The overall rationale of the rule-making process assumes that in contrast to the current marine industry practice where the designer/builder typically demonstrates compliance with regulatory requirements, in the future the nuclear regulators will wish to ensure that it is the operator of the nuclear plant that demonstrates safety in operation, in addition to the safety through design and construction. Nuclear ships are currently the responsibility of their own countries, but none are involved in international trade. Lloyd’s Register said it expected to “see nuclear ships on specific trade routes sooner than many people currently anticipate.”
Naval reactors undergo repeated power changes for ship maneuvering, unlike civilian counterparts which operate at steady state. Nuclear safety, radiation, shock, quieting, and operating performance requirements in addition to operation in close proximity to the crew dictate exceptionally high standards for component manufacturing and quality assurance. The internals of a Naval reactor remain inaccessible for inspection or replacement throughout a long core life — unlike a typical commercial nuclear reactor, which is opened for refueling roughly every eighteen months.
With the demise of the commercial nuclear industry in the 1970’s, Naval nuclear suppliers have had virtually no other work to help absorb overhead and sustain a solid business base from which to compete for Naval nuclear work. The result has been reduced competition and higher costs. Requirements for naval nuclear propulsion plant components are far more stringent than needed for civilian products. Costly quality control and work production procedures to meet nuclear requirements generally prevent these firms from competing successfully with firms geared for less sophisticated civilian work. There is no civilian demand for quiet, compact, shock-resistent nuclear propulsion systems which would keep skilled designers and production workers current. This is a distinct difference from the aerospace, electronics, and ground vehicle industries from which DOD buys many of its weapon systems.
Naval Nuclear Propulsion Plants
In naval nuclear propulsion plants, fissioning of uranium atoms in the reactor core produces heat. Because the fission process also produces radiation, shielding is placed around the reactor to protect the crew. Despite close proximity to a reactor core, a typical crewmember receives less exposure to radiation than one who remains ashore and works in an office building.