Classes of nuclear reactors used by the United States Navy
46°33′54.8″N
119°31′09.7″W
/
46.565222°N 119.519361°W
/
46.565222; -119.519361
United States naval reactors
are
nuclear reactors
used by the
United States Navy
aboard certain ships to generate the
steam
used to produce
power
for
propulsion
,
electric power
, catapulting airplanes in
aircraft carriers
, and a few more minor uses. Such naval nuclear reactors have a complete
power plant
associated with them. All commissioned U.S. Navy
submarines
and
supercarriers
built since 1975 are
nuclear powered
, with the last conventional carrier,
USS
Kitty Hawk
, being decommissioned in May 2009. The U.S. Navy also had nine nuclear-powered
cruisers
with such reactors, but they have since been decommissioned as well.
Reactors are designed by a variety of contractors,
[
who?
]
then developed and tested at one of several
Department of Energy
-owned and prime contractor-operated facilities:
Bettis Atomic Power Laboratory
in
West Mifflin, Pennsylvania
and its associated
Naval Reactors Facility
in
Idaho
, and
Knolls Atomic Power Laboratory
in
Niskayuna, New York
and its associated Kesselring site in
West Milton, New York
, 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 (in
Connecticut
) to test the nuclear plants, which were operated for years to train nuclear-qualified sailors.
Reactor designations
[
edit
]
Each reactor design is given a three-character designation consisting of:
For example, a
S9G reactor
represents a submarine (
S
), ninth-generation (
9
), General Electric designed reactor (
G
).
History
[
edit
]
Conceptual analysis of
nuclear marine propulsion
started in the 1940s. Research on developing nuclear reactors for the Navy was done at
Bettis Atomic Power Laboratory
in
West Mifflin, Pennsylvania
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 U.S. 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
USS
Nautilus
, 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
(37?46 km/h; 23?29 mph) submerged for weeks on end.
Much of the early development work on naval reactors was done at the Naval Reactors 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
USS
Seawolf
, 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
pressurized water reactor
(PWR) as the standard U.S. 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 U.S. naval reactors have been PWRs, while the
Soviet Navy
used mainly PWRs, but also used lead-bismuth cooled
liquid metal cooled reactors
(LMFR) of three types in eight submarines:
K-27
and the seven-member
Alfa class
.
Experience with USS
Nautilus
led to the parallel development of further (
Skate
-class
) submarines, powered by single reactors, and an
aircraft carrier
,
USS
Enterprise
, powered by eight
A2W
reactor units in 1960. A cruiser,
USS
Long Beach
, followed in 1961 and was powered by two
C1W
reactor units. USS
Enterprise
remained in service for over 50 years, and was inactivated in 2012.
Full-scale land-based prototype plants in Idaho, New York, and Connecticut preceded development of several types (generations) of U.S. 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 U.S. 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 U.S. 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 as the
PWR1
for
Royal Navy
submarines and then developed the design further to the PWR2. 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 disclosed a reactor accident,
[1]
[2]
but has suffered at least one coolant loss accident, on the
USS Guardfish
.
[3]
All nine of the U.S. 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 U.S. Navy ships or submarines, two nuclear-powered submarines,
USS
Thresher
and
USS
Scorpion
were lost at sea. The condition of these reactors has not been publicly released, although both wrecks have been investigated by
Robert Ballard
on behalf of the Navy using
remotely operated vehicles
(ROVs).
[
citation needed
]
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.
Power plants
[
edit
]
Current U.S. naval reactors are all pressurized water reactors,
[4]
which are identical to PWR commercial reactors producing electricity, except 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 uranium
(>20% U-235, current U.S. submarines use fuel enriched to at least 93%)
[5]
- They have long core lives, so that refueling is needed only after 10 or more years, and new cores are designed to last 25 years in carriers and 10?33 years in submarines,
- The design enables a compact pressure vessel while maintaining safety.
[
clarification needed
]
Long core life is enabled by high uranium enrichment and by incorporating a "
burnable neutron poison
", which is progressively depleted as
non-burnable poisons
like
fission products
and
actinides
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
Rubis
-class
submarines have a 48 MW reactor that needs no refueling for 30 years.
The nuclear navies of the United States, the United Kingdom, and the Russian Federation rely on steam turbine propulsion. Those of the French and Chinese use the turbine to generate electricity for propulsion. Most Russian submarines as well as all U.S. surface ships since
Enterprise
are powered by two or more reactors. U.S., British, French, Chinese and Indian submarines are powered by one.
Decommissioning nuclear-powered submarines has become a major task for American and Russian navies.
[6]
After defuelling, U.S. 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
).
See also
[
edit
]
References
[
edit
]
External links
[
edit
]
|
---|
Aircraft carrier
| |
---|
Cruiser
| |
---|
Destroyer
| |
---|
Submarine
| |
---|
|