United States Naval reactor
Encyclopedia
United States Naval reactor refers to nuclear reactor
s used by the United States Navy
aboard certain ships to produce power
for propulsion
, electric power
, catapulting airplanes in aircraft carrier
s, and a few more minor uses. Such Naval nuclear reactors have a complete power plant associated with them. All US Navy submarine
s and supercarrier
s built for the past couple of decades are nuclear-powered
by such reactors. There are no commissioned conventional (non-nuclear) submarines or aircraft carriers left in the US Navy, since the last conventional carrier, , was decommissioned in May 2009. The US Navy had nine nuclear-powered cruiser
s with such reactors also, but they have since been decommissioned. Reactors are designed by a variety of contractors, then developed and tested at one of several government (Department of Energy
)-owned and prime contractor-operated facilities. These facilities include Bettis Atomic Power Laboratory
in West Mifflin, PA
and its associated Naval Reactors Facility
in Idaho
, and Knolls Atomic Power Laboratory
in Niskayuna, NY and its associated Kesselring site in West Milton, NY
, all under the management of the office of Naval Reactors
. Sometimes there were full-scale nuclear-powered prototype
plants built at the Naval Reactors Facility, Kesselring, and Windsor Locks (in CT
) to test the nuclear plants, which were operated for years to train nuclear-qualified sailors.
For example, a S9G reactor
represents a submarine (S), ninth-generation (9), General Electric designed reactor (G).
in West Mifflin, PA starting in 1948. Under the long-term leadership of Admiral
Hyman G. Rickover
, the first test reactor plant, a prototype
referred to as S1W
, started up in USA in 1953 at the Naval Reactors Facility
in Idaho. Bettis Laboratory and Naval Reactors Facility were operated initially and for many decades afterwards by Westinghouse. The first nuclear-powered vessel, the submarine
, put to sea in 1955. USS Nautilus marked the beginning of the transition of submarines from relatively slow and short-ranged conventional submarines to ones capable of sustaining 20–25 knots (35–45 km/h) submerged for weeks on end.
Much of the early development work on naval reactors was done at the Naval Reactor Facility on the campus of the Idaho National Laboratory
(INL, previously INEL). USS Nautilus was powered by the S2W reactor
, and crew were trained on the land-based S1W reactor
at INL.
The second nuclear submarine was , which was initially powered by a sodium-cooled S2G reactor
, and supported by the land-based S1G reactor
at the Kesselring site under Knolls Atomic Power Laboratory
operated by General Electric
. A spare S2G was also built but never used.
USS Seawolf was plagued by superheater problems, with the result that USS Nautilus delivered far superior performance. This and the risks posed by liquid sodium in the event of an accident at sea led Admiral Rickover to select the PWR (pressurized water reactor
) as the standard US naval reactor type. The S2G was removed from USS Seawolf and replaced by the S2Wa reactor
, using components from the spare S2W that was part of the USS Nautilus program. All subsequent US naval reactors have been PWRs, while the Soviet Navy
used mainly PWRs, but also used lead-bismuth cooled LMFRs of three types in eight submarines: K-27
and the seven-member .
Experience with the USS Nautilus led to the parallel development of further submarines, powered by single reactors, and an aircraft carrier, , powered by eight A2W reactor units in 1960. A cruiser, , followed in 1961 and was powered by two C1W reactor units. Remarkably, USS Enterprise remains in service, although scheduled for retirement in 2013.
Full-scale land-based prototype plants in Idaho, New York, and Connecticut preceded development of several types (generations) of US Naval nuclear reactors, although not all of them. After initial construction, some engineering testing was done and the prototypes were used to train nuclear-qualified sailors for many years afterwards. For example, the A1W prototype at Naval Reactors Facility led to development of A2W reactors used in USS Enterprise. By 1962, the US Navy had 26 nuclear submarines operational and 30 under construction. Nuclear power had revolutionized the Navy.
The technology was shared with the United Kingdom
, while technological development in France
, China
and the Soviet Union
proceeded separately.
After the Skate-class vessels, reactor development proceeded and in the USA a single series of standardized designs was built by both Westinghouse and General Electric
, with one reactor powering each vessel. Rolls Royce
built similar units for Royal Navy
submarines and then developed the design further to the PWR-2. Numerous submarines with an S5W reactor plant were built.
At the end of the Cold War
in 1989, there were over 400 nuclear-powered submarines operational or being built. Some 250 of these submarines have now been scrapped and some on order canceled, due to weapons reduction programs. The Russian Navy and United States Navy had over one hundred each, with the United Kingdom and France less than twenty each and China six. The total today is about 160.
The United States is the main navy with nuclear-powered aircraft carriers (10), while Russia has nuclear-powered cruisers. Russia has eight nuclear icebreakers
in service or building. Since its inception in 1948, the U.S. Navy nuclear program has developed 27 different plant designs, installed them in 210 nuclear powered ships, taken 500 reactor cores into operation, and accumulated over 5,400 reactor years of operation and 128,000,000 miles safely steamed. Additionally, 98 nuclear submarines and six nuclear cruisers have been recycled. The U.S. Navy has never experienced a reactor accident.
Note that all nine of the US Navy nuclear-powered cruisers (CGN) have now been stricken from the Naval Vessel Register
, and those not already scrapped by recycling are scheduled to be recycled. While reactor accidents have not sunk any US Navy ships or submarines, two nuclear-powered submarines, and were lost at sea. The condition of these reactors has not been publicly released, although both wrecks have been investigated by Dr. Robert Ballard
on behalf of the Navy using remotely operated vehicles (ROVs).
Congress has mandated that the U.S. Navy consider nuclear power as an option on all large surface combatants (cruisers, destroyers) and amphibious assault ships. If proven cost-effective in a life cycle cost analysis during the Analysis of Alternatives
(AoA) phase of preliminary ship design, new ship classes (e.g. CG(X)) could proceed with nuclear propulsion.
s, which differ from commercial reactors producing electricity in that:
Long core life is enabled by high uranium enrichment and by incorporating a "burnable neutron poison
", which is progressively depleted as non-burnable poison
s like fission product
s and actinide
s accumulate. The loss of burnable poison counterbalances the creation of non-burnable poisons and result in stable long term fuel efficiency
.
Long-term integrity of the compact reactor pressure vessel is maintained by providing an internal neutron shield. (This is in contrast to early Soviet civil PWR designs where embrittlement occurs due to neutron bombardment of a very narrow pressure vessel.)
Reactor sizes range up to ~500 MWt (about 165 MWe) in the larger submarines and surface ships. The French s have a 48 MW reactor that needs no refueling for 30 years.
The Russian, US and British navies rely on steam turbine propulsion, the French and Chinese use the turbine to generate electricity for propulsion. Most Russian submarines as well as all US surface ships since Enterprise are powered by two or more reactors. US, British, French and Chinese submarines are powered by one.
Decommissioning nuclear-powered submarines has become a major task for US and Russian navies. After defuelling, US practice is to cut the reactor section from the vessel for disposal in shallow land burial as low-level waste (see the Ship-Submarine recycling program
). In Russia the whole vessels, or the sealed reactor sections, remain stored afloat indefinitely.
Other small, easily field-deployed reactor designs have been developed but have no connection to the U.S. Naval Reactor program. A small reactor was used to supply power (1.5 MWe
) and heating to McMurdo Station
, a US Antarctic
base, for ten years to 1972, testing the feasibility of such air-portable units for remote locations. Two others were installed in Arctic locations, all constructed as part of the US Army Nuclear Power Program
. A fourth mounted on a barge provided power and fresh water in the Panama Canal Zone
. Russia is well advanced with plans to build a floating power plant for their far eastern territories. The design has two 35 MWe units based on the KLT-40 reactor
used in icebreakers (with refueling every 4 years).
Nuclear reactor
A nuclear reactor is a device to initiate and control a sustained nuclear chain reaction. Most commonly they are used for generating electricity and for the propulsion of ships. Usually heat from nuclear fission is passed to a working fluid , which runs through turbines that power either ship's...
s used by the United States Navy
United States Navy
The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...
aboard certain ships to produce power
Power (physics)
In physics, power is the rate at which energy is transferred, used, or transformed. For example, the rate at which a light bulb transforms electrical energy into heat and light is measured in watts—the more wattage, the more power, or equivalently the more electrical energy is used per unit...
for propulsion
Marine propulsion
Marine propulsion is the mechanism or system used to generate thrust to move a ship or boat across water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting a motor or engine turning a propeller, or less frequently, in jet...
, electric power
Electric power
Electric power is the rate at which electric energy is transferred by an electric circuit. The SI unit of power is the watt.-Circuits:Electric power, like mechanical power, is represented by the letter P in electrical equations...
, catapulting airplanes in aircraft carrier
Aircraft carrier
An aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
s, and a few more minor uses. Such Naval nuclear reactors have a complete power plant associated with them. All US Navy submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
s and supercarrier
Supercarrier
Supercarrier is an unofficial descriptive term for the largest type of aircraft carrier, usually displacing over 70,000 long tons.Supercarrier is an unofficial descriptive term for the largest type of aircraft carrier, usually displacing over 70,000 long tons.Supercarrier is an unofficial...
s built for the past couple of decades are nuclear-powered
Nuclear power
Nuclear power is the use of sustained nuclear fission to generate heat and electricity. Nuclear power plants provide about 6% of the world's energy and 13–14% of the world's electricity, with the U.S., France, and Japan together accounting for about 50% of nuclear generated electricity...
by such reactors. There are no commissioned conventional (non-nuclear) submarines or aircraft carriers left in the US Navy, since the last conventional carrier, , was decommissioned in May 2009. The US Navy had nine nuclear-powered cruiser
Cruiser
A cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...
s with such reactors also, but they have since been decommissioned. Reactors are designed by a variety of contractors, then developed and tested at one of several government (Department of Energy
United States Department of Energy
The United States Department of Energy is a Cabinet-level department of the United States government concerned with the United States' policies regarding energy and safety in handling nuclear material...
)-owned and prime contractor-operated facilities. These facilities include Bettis Atomic Power Laboratory
Bettis Atomic Power Laboratory
Bettis Atomic Power Laboratory is a U.S. Government-owned, contractor-operated research and development facility located in the Pittsburgh suburb of West Mifflin, Pennsylvania. It solely focuses on the design and development of nuclear power for the U.S. Navy....
in West Mifflin, PA
West Mifflin, Pennsylvania
West Mifflin is a borough in Allegheny County, Pennsylvania, United States, located southeast of downtown Pittsburgh. The population was 20,313 at the 2010 census....
and its associated Naval Reactors Facility
Naval Reactors Facility
Naval Reactors Facility is located 52 miles northwest of Idaho Falls. The NRF is a United States Department of Energy-Naval Reactors facility where three nuclear propulsion prototypes A1W, S1W and S5G were located...
in Idaho
Idaho
Idaho is a state in the Rocky Mountain area of the United States. The state's largest city and capital is Boise. Residents are called "Idahoans". Idaho was admitted to the Union on July 3, 1890, as the 43rd state....
, and Knolls Atomic Power Laboratory
Knolls Atomic Power Laboratory
Knolls Atomic Power Laboratory is a research and development facility dedicated to the support of the US Naval Nuclear Propulsion Program. KAPL is a government-owned, contractor operated laboratory run by Bechtel Marine Propulsion Corporation for the United States Department of Energy. KAPL is...
in Niskayuna, NY and its associated Kesselring site in West Milton, NY
West Milton, New York
West Milton is a hamlet in Ballston Spa, Saratoga County, New York. It lies at an elevation of 440 feet ....
, all under the management of the office of Naval Reactors
Naval Reactors
Naval Reactors is an umbrella term for the U.S. government office that has comprehensive responsibility for the continued safe and reliable operation of the United States Navy's nuclear propulsion program and thus for United States Naval reactors...
. Sometimes there were full-scale nuclear-powered prototype
Prototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...
plants built at the Naval Reactors Facility, Kesselring, and Windsor Locks (in CT
Connecticut
Connecticut is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south .Connecticut is named for the Connecticut River, the major U.S. river that approximately...
) to test the nuclear plants, which were operated for years to train nuclear-qualified sailors.
Reactor designations
Each reactor design is given a three-character designation consisting of:- A letter for the type of ship the reactor is intended for ("A" for aircraft carrierAircraft carrierAn aircraft carrier is a warship designed with a primary mission of deploying and recovering aircraft, acting as a seagoing airbase. Aircraft carriers thus allow a naval force to project air power worldwide without having to depend on local bases for staging aircraft operations...
, "C" for cruiserCruiserA cruiser is a type of warship. The term has been in use for several hundreds of years, and has had different meanings throughout this period...
, "D" for destroyerDestroyerIn naval terminology, a destroyer is a fast and maneuverable yet long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against smaller, powerful, short-range attackers. Destroyers, originally called torpedo-boat destroyers in 1892, evolved from...
, and "S" for submarineSubmarineA submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
) - A consecutive generation number
- A letter for the reactor's designer ("W" for WestinghouseWestinghouse Electric (1886)Westinghouse Electric was an American manufacturing company. It was founded in 1886 as Westinghouse Electric Company and later renamed Westinghouse Electric Corporation by George Westinghouse. The company purchased CBS in 1995 and became CBS Corporation in 1997...
, "G" for General ElectricGeneral ElectricGeneral Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
, "C" for Combustion EngineeringCombustion EngineeringCombustion Engineering was an American engineering firm and leading firm in the development of power systems in the United States with approximately 30,000 employees in about a dozen states at its peak. Headquartered in Stamford, Connecticut, C-E owned over two dozen other companies including...
, and "B" for BechtelBechtelBechtel Corporation is the largest engineering company in the United States, ranking as the 5th-largest privately owned company in the U.S...
)
For example, a S9G reactor
S9G reactor
The S9G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on Virginia class submarines...
represents a submarine (S), ninth-generation (9), General Electric designed reactor (G).
History
Conceptual analysis of nuclear marine propulsion started in the 1940s. Research on developing nuclear reactors for the Navy was done at Bettis Atomic Power LaboratoryBettis Atomic Power Laboratory
Bettis Atomic Power Laboratory is a U.S. Government-owned, contractor-operated research and development facility located in the Pittsburgh suburb of West Mifflin, Pennsylvania. It solely focuses on the design and development of nuclear power for the U.S. Navy....
in West Mifflin, PA starting in 1948. Under the long-term leadership of Admiral
Admiral
Admiral is the rank, or part of the name of the ranks, of the highest naval officers. It is usually considered a full admiral and above vice admiral and below admiral of the fleet . It is usually abbreviated to "Adm" or "ADM"...
Hyman G. Rickover
Hyman G. Rickover
Hyman George Rickover was a four-star admiral of the United States Navy who directed the original development of naval nuclear propulsion and controlled its operations for three decades as director of Naval Reactors...
, the first test reactor plant, a prototype
Prototype
A prototype is an early sample or model built to test a concept or process or to act as a thing to be replicated or learned from.The word prototype derives from the Greek πρωτότυπον , "primitive form", neutral of πρωτότυπος , "original, primitive", from πρῶτος , "first" and τύπος ,...
referred to as S1W
S1W reactor
The S1W reactor was the first prototype naval reactor used by the United States Navy to prove that the technology could be used for electricity generation and propulsion on submarines...
, started up in USA in 1953 at the Naval Reactors Facility
Naval Reactors Facility
Naval Reactors Facility is located 52 miles northwest of Idaho Falls. The NRF is a United States Department of Energy-Naval Reactors facility where three nuclear propulsion prototypes A1W, S1W and S5G were located...
in Idaho. Bettis Laboratory and Naval Reactors Facility were operated initially and for many decades afterwards by Westinghouse. The first nuclear-powered vessel, the submarine
Submarine
A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...
, put to sea in 1955. USS Nautilus marked the beginning of the transition of submarines from relatively slow and short-ranged conventional submarines to ones capable of sustaining 20–25 knots (35–45 km/h) submerged for weeks on end.
Much of the early development work on naval reactors was done at the Naval Reactor Facility on the campus of the Idaho National Laboratory
Idaho National Laboratory
Idaho National Laboratory is an complex located in the high desert of eastern Idaho, between the town of Arco to the west and the cities of Idaho Falls and Blackfoot to the east. It lies within Butte, Bingham, Bonneville and Jefferson counties...
(INL, previously INEL). USS Nautilus was powered by the S2W reactor
S2W reactor
The S2W reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S2W designation stands for:* S = Submarine platform* 2 = Second generation core designed by the contractor...
, and crew were trained on the land-based S1W reactor
S1W reactor
The S1W reactor was the first prototype naval reactor used by the United States Navy to prove that the technology could be used for electricity generation and propulsion on submarines...
at INL.
The second nuclear submarine was , which was initially powered by a sodium-cooled S2G reactor
S2G reactor
The S2G reactor was a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships, and the only liquid metal cooled reactor yet deployed by the US Navy...
, and supported by the land-based S1G reactor
S1G reactor
The S1G reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S1G designation stands for:* S = Submarine platform* 1 = First generation core designed by the contractor...
at the Kesselring site under Knolls Atomic Power Laboratory
Knolls Atomic Power Laboratory
Knolls Atomic Power Laboratory is a research and development facility dedicated to the support of the US Naval Nuclear Propulsion Program. KAPL is a government-owned, contractor operated laboratory run by Bechtel Marine Propulsion Corporation for the United States Department of Energy. KAPL is...
operated by General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
. A spare S2G was also built but never used.
USS Seawolf was plagued by superheater problems, with the result that USS Nautilus delivered far superior performance. This and the risks posed by liquid sodium in the event of an accident at sea led Admiral Rickover to select the PWR (pressurized water reactor
Pressurized water reactor
Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...
) as the standard US naval reactor type. The S2G was removed from USS Seawolf and replaced by the S2Wa reactor
S2Wa reactor
The S2Wa reactor is a naval reactor used by the United States Navy to provide electricity generation and propulsion on warships. The S2Wa designation stands for:* S = Submarine platform* 2 = Second generation core designed by the contractor...
, using components from the spare S2W that was part of the USS Nautilus program. All subsequent US naval reactors have been PWRs, while the Soviet Navy
Soviet Navy
The Soviet Navy was the naval arm of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy would have played an instrumental role in a Warsaw Pact war with NATO, where it would have attempted to prevent naval convoys from bringing reinforcements across the Atlantic Ocean...
used mainly PWRs, but also used lead-bismuth cooled LMFRs of three types in eight submarines: K-27
Soviet submarine K-27
The K-27 was the only submarine of Projekt 645 in the Soviet Navy. Project 645 did not have or need its own NATO reporting name. That project produced just one test model nuclear submarine, one which incorporated a pair of experimental VT-1 nuclear reactors that used a liquid-metal coolant ,...
and the seven-member .
Experience with the USS Nautilus led to the parallel development of further submarines, powered by single reactors, and an aircraft carrier, , powered by eight A2W reactor units in 1960. A cruiser, , followed in 1961 and was powered by two C1W reactor units. Remarkably, USS Enterprise remains in service, although scheduled for retirement in 2013.
Full-scale land-based prototype plants in Idaho, New York, and Connecticut preceded development of several types (generations) of US Naval nuclear reactors, although not all of them. After initial construction, some engineering testing was done and the prototypes were used to train nuclear-qualified sailors for many years afterwards. For example, the A1W prototype at Naval Reactors Facility led to development of A2W reactors used in USS Enterprise. By 1962, the US Navy had 26 nuclear submarines operational and 30 under construction. Nuclear power had revolutionized the Navy.
The technology was shared with the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, while technological development in France
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
and the Soviet Union
Soviet Union
The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....
proceeded separately.
After the Skate-class vessels, reactor development proceeded and in the USA a single series of standardized designs was built by both Westinghouse and General Electric
General Electric
General Electric Company , or GE, is an American multinational conglomerate corporation incorporated in Schenectady, New York and headquartered in Fairfield, Connecticut, United States...
, with one reactor powering each vessel. Rolls Royce
Rolls-Royce plc
Rolls-Royce Group plc is a global power systems company headquartered in the City of Westminster, London, United Kingdom. It is the world’s second-largest maker of aircraft engines , and also has major businesses in the marine propulsion and energy sectors. Through its defence-related activities...
built similar units for Royal Navy
Royal Navy
The Royal Navy is the naval warfare service branch of the British Armed Forces. Founded in the 16th century, it is the oldest service branch and is known as the Senior Service...
submarines and then developed the design further to the PWR-2. Numerous submarines with an S5W reactor plant were built.
At the end of the Cold War
Cold War
The Cold War was the continuing state from roughly 1946 to 1991 of political conflict, military tension, proxy wars, and economic competition between the Communist World—primarily the Soviet Union and its satellite states and allies—and the powers of the Western world, primarily the United States...
in 1989, there were over 400 nuclear-powered submarines operational or being built. Some 250 of these submarines have now been scrapped and some on order canceled, due to weapons reduction programs. The Russian Navy and United States Navy had over one hundred each, with the United Kingdom and France less than twenty each and China six. The total today is about 160.
The United States is the main navy with nuclear-powered aircraft carriers (10), while Russia has nuclear-powered cruisers. Russia has eight nuclear icebreakers
Nuclear powered icebreaker
A nuclear powered icebreaker is a purpose-built ship for use in waters continuously covered with ice. Icebreakers are ships capable of cruising on ice-covered water by breaking through the ice with their strong, heavy, steel bows...
in service or building. Since its inception in 1948, the U.S. Navy nuclear program has developed 27 different plant designs, installed them in 210 nuclear powered ships, taken 500 reactor cores into operation, and accumulated over 5,400 reactor years of operation and 128,000,000 miles safely steamed. Additionally, 98 nuclear submarines and six nuclear cruisers have been recycled. The U.S. Navy has never experienced a reactor accident.
Note that all nine of the US Navy nuclear-powered cruisers (CGN) have now been stricken from the Naval Vessel Register
Naval Vessel Register
The Naval Vessel Register is the official inventory of ships and service craft in custody of or titled by the United States Navy. It contains information on ships and service craft that make up the official inventory of the Navy from the time a vessel is authorized through its life cycle and...
, and those not already scrapped by recycling are scheduled to be recycled. While reactor accidents have not sunk any US Navy ships or submarines, two nuclear-powered submarines, and were lost at sea. The condition of these reactors has not been publicly released, although both wrecks have been investigated by Dr. Robert Ballard
Robert Ballard
Robert Duane Ballard is a former United States Navy officer and a professor of oceanography at the University of Rhode Island who is most noted for his work in underwater archaeology. He is most famous for the discoveries of the wrecks of the RMS Titanic in 1985, the battleship Bismarck in 1989,...
on behalf of the Navy using remotely operated vehicles (ROVs).
Congress has mandated that the U.S. Navy consider nuclear power as an option on all large surface combatants (cruisers, destroyers) and amphibious assault ships. If proven cost-effective in a life cycle cost analysis during the Analysis of Alternatives
Analysis of Alternatives
This article refers to the Analysis of Alternatives military process, not the general business practice. The AoA is a cornerstone of Military Acquisition, and deliberately embodies the fair and competitive character of the United States business atmosphere...
(AoA) phase of preliminary ship design, new ship classes (e.g. CG(X)) could proceed with nuclear propulsion.
Power plants
U.S. Naval reactors are pressurized water reactorPressurized water reactor
Pressurized water reactors constitute a large majority of all western nuclear power plants and are one of three types of light water reactor , the other types being boiling water reactors and supercritical water reactors...
s, which differ from commercial reactors producing electricity in that:
- they have a high power density in a small volume and run either on low-enriched uranium (as do some French and Chinese submarines) or on highly enriched uraniumEnriched uraniumEnriched uranium is a kind of uranium in which the percent composition of uranium-235 has been increased through the process of isotope separation. Natural uranium is 99.284% 238U isotope, with 235U only constituting about 0.711% of its weight...
(>20% U-235, current U.S. submarines use fuel enriched to at least 93%, compared to between 21–45% in current Russian models, although Russian nuclear-powered icebreaker reactors are enriched up to 90%), - the fuel is not UO2 but a metal-zirconiumZirconiumZirconium is a chemical element with the symbol Zr and atomic number 40. The name of zirconium is taken from the mineral zircon. Its atomic mass is 91.224. It is a lustrous, grey-white, strong transition metal that resembles titanium...
alloy (c.15% U with 93% enrichment, or more U with lower enrichment), - they have long core lives, so that refueling is needed only after 10 or more years, and new cores are designed to last 50 years in carriers and 30–40 years in submarines,
- the design enables a compact pressure vessel while maintaining safety.
Long core life is enabled by high uranium enrichment and by incorporating a "burnable neutron poison
Nuclear poison
A neutron poison is a substance with a large neutron absorption cross-section in applications, such as nuclear reactors. In such applications, absorbing neutrons is normally an undesirable effect...
", which is progressively depleted as non-burnable poison
Nuclear poison
A neutron poison is a substance with a large neutron absorption cross-section in applications, such as nuclear reactors. In such applications, absorbing neutrons is normally an undesirable effect...
s like fission product
Fission product
Nuclear fission products are the atomic fragments left after a large atomic nucleus fissions. Typically, a large nucleus like that of uranium fissions by splitting into two smaller nuclei, along with a few neutrons and a large release of energy in the form of heat , gamma rays and neutrinos. The...
s and actinide
Actinide
The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.The actinide series derives its name from the group 3 element actinium...
s accumulate. The loss of burnable poison counterbalances the creation of non-burnable poisons and result in stable long term fuel efficiency
Fuel efficiency
Fuel efficiency is a form of thermal efficiency, meaning the efficiency of a process that converts chemical potential energy contained in a carrier fuel into kinetic energy or work. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is...
.
Long-term integrity of the compact reactor pressure vessel is maintained by providing an internal neutron shield. (This is in contrast to early Soviet civil PWR designs where embrittlement occurs due to neutron bombardment of a very narrow pressure vessel.)
Reactor sizes range up to ~500 MWt (about 165 MWe) in the larger submarines and surface ships. The French s have a 48 MW reactor that needs no refueling for 30 years.
The Russian, US and British navies rely on steam turbine propulsion, the French and Chinese use the turbine to generate electricity for propulsion. Most Russian submarines as well as all US surface ships since Enterprise are powered by two or more reactors. US, British, French and Chinese submarines are powered by one.
Decommissioning nuclear-powered submarines has become a major task for US and Russian navies. After defuelling, US practice is to cut the reactor section from the vessel for disposal in shallow land burial as low-level waste (see the Ship-Submarine recycling program
Ship-Submarine recycling program
The Ship/Submarine Recycling Program is the process the United States Navy uses to dispose of decommissioned nuclear vessels. SRP takes place only at the Puget Sound Naval Shipyard in Bremerton, Washington, but the preparations can begin elsewhere....
). In Russia the whole vessels, or the sealed reactor sections, remain stored afloat indefinitely.
Other small, easily field-deployed reactor designs have been developed but have no connection to the U.S. Naval Reactor program. A small reactor was used to supply power (1.5 MWe
MWE
MWE may refer to:*Manufacturer's Weight Empty*McDermott Will & Emery*Midwest Express, an airline*Merowe Airport - IATA code*Multiword expressionMWe may refer to:*Megawatt electrical...
) and heating to McMurdo Station
McMurdo Station
McMurdo Station is a U.S. Antarctic research center located on the southern tip of Ross Island, which is in the New Zealand-claimed Ross Dependency on the shore of McMurdo Sound in Antarctica. It is operated by the United States through the United States Antarctic Program, a branch of the National...
, a US Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...
base, for ten years to 1972, testing the feasibility of such air-portable units for remote locations. Two others were installed in Arctic locations, all constructed as part of the US Army Nuclear Power Program
Army Nuclear Power Program
The Army Nuclear Power Program was a program of the United States Army to develop small pressurized water and boiling water nuclear power reactors to generate electrical and space-heating energy primarily at remote, relatively inaccessible sites. The ANPP had several notable accomplishments, but...
. A fourth mounted on a barge provided power and fresh water in the Panama Canal Zone
Panama Canal Zone
The Panama Canal Zone was a unorganized U.S. territory located within the Republic of Panama, consisting of the Panama Canal and an area generally extending 5 miles on each side of the centerline, but excluding Panama City and Colón, which otherwise would have been partly within the limits of...
. Russia is well advanced with plans to build a floating power plant for their far eastern territories. The design has two 35 MWe units based on the KLT-40 reactor
KLT-40 reactor
The KLT-40 and KLT-40M reactors are nuclear fission reactors used to power the Taymyr-class icebreakers and the LASH carrier Sevmorput...
used in icebreakers (with refueling every 4 years).
See also
- List of United States Naval reactors
- Naval ReactorsNaval ReactorsNaval Reactors is an umbrella term for the U.S. government office that has comprehensive responsibility for the continued safe and reliable operation of the United States Navy's nuclear propulsion program and thus for United States Naval reactors...
- Nuclear marine propulsionNuclear marine propulsionNuclear marine propulsion is propulsion of a ship by a nuclear reactor. Naval nuclear propulsion is propulsion that specifically refers to naval warships...
- Naval Nuclear Power School
- Radioisotope thermoelectric generatorRadioisotope thermoelectric generatorA radioisotope thermoelectric generator is an electrical generator that obtains its power from radioactive decay. In such a device, the heat released by the decay of a suitable radioactive material is converted into electricity by the Seebeck effect using an array of thermocouples.RTGs can be...
External links
- The Uranium Information Centre provided some of the original material in this article.