Nuclear-Powered Ships
http://www.world-nuclear.org/info/Non-Power-Nuclear-Applications/Transport/Nuclear-Powered-Ships/#.UhbjGn-N6So
(Updated August 2013)
- Nuclear power is particularly suitable for vessels which need to be at sea for long periods without refuelling, or for powerful submarine propulsion.
- Some 140 ships are powered by more than 180 small nuclear reactors and more than 12,000 reactor years of marine operation has been accumulated.
- Most are submarines, but they range from icebreakers to aircraft carriers.
- In future, constraints on fossil fuel use in transport may bring marine nuclear propulsion into more widespread use. So far, exaggerated fears about safety have caused political restriction on port access.
Work on nuclear marine propulsion started in the 1940s, and the first
test reactor started up in USA in 1953. The first nuclear-powered
submarine, USS Nautilus, put to sea in 1955.
This marked the transition of submarines from slow underwater vessels
to warships capable of sustaining 20-25 knots submerged for weeks on
end. The submarine had come into its own.
Nautilus led to the parallel development of further (Skate-class) submarines, powered by single pressurised water reactors, and an aircraft carrier, USS Enterprise, powered by eight reactor units in 1960. A cruiser, USS Long Beach, followed in 1961 and was powered by two of these early units. Remarkably, the Enterprise remained in service to the end of 2012.
By 1962 the US Navy had 26 nuclear submarines operational and 30 under construction. Nuclear power had revolutionised the Navy.
The technology was shared with Britain, while French, Russian and Chinese developments proceeded separately.
After the Skate-class vessels, reactor development proceeded and in
the USA a single series of standardised designs was built by both
Westinghouse and GE, one reactor powering each vessel. Rolls Royce built
similar units for Royal Navy submarines and then developed the design
further to the PWR-2.
Russia developed both PWR and lead-bismuth cooled reactor designs,
the latter not persisting. Eventually four generations* of submarine
PWRs were utilised, the last entering service in 1995 in the Severodvinsk class.
* 1955-66, 1963-92, 1976-2003, 1995 on, according to Bellona.
The largest submarines are the 26,500 tonne (34,000 t submerged) Russian Typhoon-class, powered by twin 190 MWt PWR reactors, though these were superseded by the 24,000 t Oscar-II class (eg Kursk) with the same power plant.
The safety record of the US nuclear navy is excellent, this being
attributed to a high level of standardisation in naval power plants and
their maintenance, and the high quality of the Navy's training program.
However, early Soviet endeavours resulted in a number of serious
accidents - five where the reactor was irreparably damaged, and more
resulting in radiation leaks. There were more than 20 radiation
fatalities. However, by Russia’s third generation of marine PWRs in the
late 1970s safety and reliability had become a high priority. (Apart
from reactor accidents, fires and accidents have resulted in the loss of
two US and about 4 Soviet submarines, another four of which had fires
resulting in loss of life.)
Lloyd's Register shows about 200 nuclear reactors at sea, and that some 700 have been used at sea since the 1950s.
Nuclear Naval Fleets
Russia built 248 nuclear submarines and five naval surface vessels
(plus 9 icebreakers) powered by 468 reactors between 1950 and 2003, and
was then operating about 60 nuclear naval vessels. (Bellona gives 247
subs with 456 reactors 1958-95.) For operational vessels in 1997,
Bellona lists 109 Russian submarines (plus 4 naval surface ships) and
108 attack submarines (SSN) and 25 ballistic missile ones apart from
Russia.
At the end of the Cold War, in 1989, there were over 400
nuclear-powered submarines operational or being built. At least 300 of
these submarines have now been scrapped and some on order cancelled, due
to weapons reduction programs*. Russia and USA had over one hundred
each in service, with UK and France less than twenty each and China six.
The total today is understood to be about 120, including new ones
commissioned. Most or all are fuelled by high-enriched uranium (HEU).
* In 2007 Russia had about 40 retired subs from its
Pacific fleet alone awaiting scrapping. In November 2008 it was
reported that Russia intended to scrap all decommissioned nuclear
submarines by 2012, the total being more than 200 of the 250 built to
date. Most Northern Fleet submarines had been dismantled at
Severodvinsk, and most remaining to be scrapped were with the Pacific
Fleet.
India launched its first submarine in 2009, the 6000 dwt Arihant
SSBN, with a single 85 MW PWR fuelled by HEU driving a 70 MW steam
turbine. It is reported to have cost US$ 2.9 billion, and several more
are planned. India is also leasing an almost-new 7900 dwt (12,770 tonne
submerged) Russian Akula-II class nuclear attack submarine for ten years from 2010, at a cost of US$ 650 million: the Chakra, formerly Nerpa. It has a single 190 MWt VM-5/ OK-659B PWR driving a 32 MW steam turbine and two 2 MWe turbogenerators.
The USA has the main navy with nuclear-powered aircraft carriers,
while both it and Russia have had nuclear-powered cruisers (USA: 9,
Russia 4). The USA had built 219 nuclear-powered vessels to mid 2010,
and then had five submarines and an aircraft carrier under construction.
All US aircraft carriers and submarines are nuclear-powered.
The US Navy has accumulated over 6200 reactor-years of accident-free
experience involving 526 nuclear reactor cores over the course of 240
million kilometres, without a single radiological incident, over a
period of more than 50 years. It operated 82 nuclear-powered ships (11
aircraft carriers, 71 submarines - 18 SSBN/SSGN, 53 SSN) with 103
reactors as of March 2010.
The Russian Navy has logged over 6000 nautical reactor-years. It
appears to have eight strategic submarines (SSBN/SSGN) in operation and
13 nuclear-powered attack submarines (SSN), plus some diesel subs.
Russia has announced that it will build eight new nuclear SSBN
submarines in its plan to 2015. Its only nuclear-powered carrier project
was cancelled in 1992. It has one nuclear-powered cruiser in operation
and three others being overhauled. In 2012 it announced that its
third-generation strategic subs would have extended service lives, from
25 to 35 years.
In 2012 construction of a nuclear-powered deep-sea submersible was
announced. This is based on the Oscar-class naval submarine and is
apparently designed for research and rescue missions. It will be built
by the Sevmash shipyard at Severodvinsk, which builds Russian naval
submarines.
China has several nuclear-powered submarines, and in February 2013 China Shipbuilding Industry Corp received state approval and funding to begin research on core technologies and safety for nuclear-powered ships, with polar vessels being mentioned but aircraft carriers being considered a more likely purpose for the new development.
China has several nuclear-powered submarines, and in February 2013 China Shipbuilding Industry Corp received state approval and funding to begin research on core technologies and safety for nuclear-powered ships, with polar vessels being mentioned but aircraft carriers being considered a more likely purpose for the new development.
France has a nuclear-powered aircraft carrier and ten nuclear
submarines (4 SSBN, 6 Rubis class SSN). The UK has 12 submarines, all
nuclear powered (4 SSBN, 8 SSN). China is understood to have about ten
nuclear submarines (possibly 3 SSBN, 7 SSN).
Civil Vessels
Nuclear propulsion has proven technically and economically essential
in the Russian Arctic where operating conditions are beyond the
capability of conventional icebreakers. The power levels required for
breaking ice up to 3 metres thick, coupled with refuelling difficulties
for other types of vessels, are significant factors. The nuclear fleet,
with six nuclear icebreakers and a nuclear freighter, has increased
Arctic navigation from 2 to 10 months per year, and in the Western
Arctic, to year-round.
The icebreaker Lenin was the world's first nuclear-powered
surface vessel (20,000 dwt), commissioned in 1959. It remained in
service for 30 years to 1989, being retired due to the hull being worn
thin from ice abrasion. It initially had three 90 MWt OK-150 reactors,
but these were badly damaged during refueling in 1965 and 1967. In 1970
they were replaced by two 171 MWt OK-900 reactors providing steam for
turbines which generated electricity to deliver 34 MW at the propellers.
It led to a series of larger icebreakers, the six 23,500 dwt Arktika-class,
launched from 1975. These powerful vessels have two 171 MWt OK-900
reactors delivering 54 MW at the propellers and are used in deep Arctic
waters. The Arktika was the first surface vessel to reach the North Pole, in 1977. Rossija, Sovetskiy Soyuz and Yamal were in service towards the end of 2008, with Sibir decommissioned and Arktika retired in October 2008.
The seventh and largest Arktika class icebreaker - 50 Years of Victory (50 Let Pobedy)
- was built by the Baltic shipyard at St Petersburg and after delays
during construction it entered service in 2007 (twelve years later than
the 50-year anniversary of 1945 it was to commemorate). It is 25,800
dwt, 160 m long and 20m wide, and is designed to break through ice up to
2.8 metres thick. Its performance in service has been impressive.
For use in shallow waters such as estuaries and rivers, two shallow-draft Taymyr-class
icebreakers of 18,260 dwt with one reactor delivering 35 MW were built
in Finland and then fitted with their nuclear steam supply system in
Russia. They - Taymyr and Vaygach - are built to conform with
international safety standards for nuclear vessels and were launched
from 1989.
Tenders were called for building the first of a new LK-60 series series
of Russian icebreakers in mid 2012, and the contract was awarded to
Baltijskyi Zavod in St Petersburg. This is to be dual-draught (10.5m
with full ballast tanks, minimum 8.55m at 25,540 t), displacing up to
33,530 t, 173 m long, 34 m wide, and designed to break through 3 m thick
ice at up to 2 knots. The wider 33 m beam at waterline is to match the
70,000 tonne ships it is designed to clear a path for, though a few of
these with reinforced hulls are already using the Northern passage.
There is scope for more use: in 2011, 19,000 ships used the Suez Canal
and only about 40 traversed the northern route.
The LK-60 will be powered by two RITM-200 reactors of 175 MWt each
using low-enriched fuel (<20%), which together deliver 60 MW at the
three propellers via twin turbine-generators and three motors. At 65%
capacity factor refuelling is every 7 years, overhaul at 20 years,
service life 40 years. It is designed to operate in the Western Arctic
– in the Barents, Pechora and Kara Seas, as well as in shallow water of
the Yenissei River and Ob Bay, for year-round pilotage (also as tug) of
tankers, dry-cargo ships and vessels with special equipment to mineral
resource development sites on the Arctic shelf. With keel laying
expected in 2013, the vessel is to be delivered to Atomflot by the end
of 2017 at a cost of RUR 37 billion.
In January 2013 Rosatom called for bids to build two more of these universal icebreaker vessels, for delivery in 2019 and 2020.
A more powerful Russian LK-110 icebreaker of 110 MW net and 55,600 dwt is planned.
Development of nuclear merchant ships began in the 1950s but on the
whole has not been commercially successful. The 22,000 tonne US-built NS Savannah,
was commissioned in 1962 and decommissioned eight years later. It was a
technical success, but not economically viable. It had a 74 MWt reactor
delivering 16.4 MW to the propeller. The German-built 15,000 tonne Otto Hahn
cargo ship and research facility sailed some 650,000 nautical miles on
126 voyages in 10 years without any technical problems. It had a 36 MWt
reactor delivering 8 MW to the propeller. However, it proved too
expensive to operate and in 1982 it was converted to diesel.
The 8000 tonne Japanese Mutsu was the third civil vessel,
put into service in 1970. It had a 36 MWt reactor delivering 8 MW to the
propeller. It was dogged by technical and political problems and was an
embarrassing failure. These three vessels used reactors with
low-enriched uranium fuel (3.7 - 4.4% U-235).
In 1988 the NS Sevmorput was commissioned in Russia, mainly
to serve northern Siberian ports. It is a 61,900 tonne 260 m long
LASH-carrier (taking lighters to ports with shallow water) and container
ship with ice-breaking bow. It is powered by the same KLT-40 reactor as
used in larger icebreakers, delivering 32.5 propeller MW from the 135
MWt reactor, and it needed refuelling only once to 2003.
Russian experience with nuclear powered Arctic ships totals about 300
reactor-years in 2009. In 2008 the Arctic fleet was transferred from
the Murmansk Shipping Company under the Ministry of Transport to
Atomflot, under Rosatom. This is progressively becoming a commercial
enterprise, with the 40% state subsidy of RUR 1262 million in 2011 due
to phase out in 2014.
In August 2010 two Arktika-class icebreakers escorted the 100,000 dwt tanker Baltika,
carrying 70,000 tonnes of gas condensate, from Murmansk to China via
the Arctic route, saving some 8000 km compared with the Suez Canal
route. In November 2012 the Ob River LNG tanker with 150,000 cubic
metres of gas as LNG, chartered by Russia's Gazprom, traversed the
northern sea route from Norway to Japan accompanied by nuclear-powered
icebreakers, the route cutting 20 days off the normal journey and
resulting in less loss of cargo. It has a strengthened hull to cope with
the Arctic ice. There are plans to ship iron ore and base metals on the
northern sea route also.
Nuclear propulsion systems
Naval reactors (with the exception of the ill-fated Russian Alfa class described below) have been pressurised water types, which differ from commercial reactors producing electricity in that:
- they deliver a lot of power from a very small volume and therefore run on highly-enriched uranium (>20% U-235, originally c 97% but apparently now 93% in latest US submarines, c 20-25% in some western vessels, 20% in the first and second generation Russian reactors (1957-81)*, then 21% to 45% in 3rd generation Russian units, 40% in India's Arihant).
- the fuel is not UO2 but a uranium-zirconium or uranium-aluminium alloy (c15%U with 93% enrichment, or more U with less - eg 20% - U-235) or a metal-ceramic (Kursk: U-Al zoned 20-45% enriched, clad in zircaloy, with c 200kg U-235 in each 200 MW core),
- they have long core lives, so that refuelling is needed only after 10 or more years, and new cores are designed to last 50 years in carriers and 30-40 years (over 1.5 million kilometres) in most submarines,
- the design enables a compact pressure vessel while maintaining safety. The Sevmorput pressure vessel for a relatively large marine reactor is 4.6 m high and 1.8 m diameter, enclosing a core 1 m high and 1.2 m diameter.
- thermal efficiency is less than in civil nuclear power plants due to the need for flexible power output, and space constraints for the steam system,
- there is no soluble boron used in naval reactors (at least US ones).
* An IAEA Tecdoc reports discharge assay of early submarine used fuel reprocessed at Mayak being 17% U-235.
The long core life is enabled by the relatively high enrichment of
the uranium and by incorporating a "burnable poison" such as gadolinium -
which is progressively depleted as fission products and actinides
accumulate. These accumulating poisons would normally cause reduced
fuel efficiency, but the two effects cancel one another out.
However, the enrichment level for newer French naval fuel has been
dropped to 7.5% U-235, the fuel being known as 'caramel', which needs to
be changed every ten years or so. This avoids the need for a specific
military enrichment line, and some reactors will be smaller versions of
those on the Charles de Gaulle. In 2006 the Defence Ministry announced that Barracuda
class subs would use fuel with "civilian enrichment, identical to that
of EdF power plants," which may be an exaggeration but certainly marks a
major change there.
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.)
The Russian, US, and British navies rely on steam turbine propulsion,
the French and Chinese in submarines use the turbine to generate
electricity for propulsion.
Russian ballistic missile submarines as well as all surface ships since the Enterprise
are powered by two reactors. Other submarines (except some Russian
attack subs) are powered by one. A new Russian test-bed submarine is
diesel-powered but has a very small nuclear reactor for auxiliary power.
The Russian Alfa-class submarines had a single liquid metal
cooled reactor (LMR) of 155 MWt and using very highly enriched uranium -
90% enriched U-Be fuel. These were very fast, but had operational
problems in ensuring that the lead-bismuth coolant did not freeze when
the reactor was shut down. The design was unsuccessful and used in only
eight trouble-plagued vessels.
The US Navy's second nuclear submarine had a sodium-cooled power plant (S2G). The USS Seawolf, SSN-575,
operated for nearly two years 1957-58 with this. The
intermediate-spectrum reactor raised its incoming coolant temperature
over ten times as much as the Nautilus' water-cooled plant,
providing superheated steam, and it offered an outlet temperature of
454°C, compared with the Nautilus’ 305°C. It was highly efficient, but
offsetting this, the plant had serious operational disadvantages. Large
electric heaters were required to keep the plant warm when the reactor
was down to avoid the sodium freezing. The biggest problem was that the
sodium became highly radioactive, with a half-life of 15 hours, so that
the whole reactor system had to be more heavily shielded than a
water-cooled plant, and the reactor compartment couldn’t be entered for
many days after shutdown. The reactor was replaced with a PWR type
(S2Wa) similar to Nautilus.
For many years the Los Angeles class submarines formed the backbone
of the US SSN (attack) fleet, and 62 were built. They are 6900 dwt
submerged, and have a 165 MW GE S6G reactor driving two 26 MW steam
turbines. Refueling interval is 30 years. The US Virginia class SSN
submarine has pump-jet propulsion built by BAE Systems and is powered by
a PWR reactor (GE S9G) which does not need refueling for 33 years.
They are about 7900 dwt, and ten were in operation as of late 2013, with
more on order.
Unlike PWRs, boiling water reactors (BWRs) circulate water which is
radioactive* outside the reactor compartment, and are also considered
too noisy for submarine use.
* Radioactivity in the cooling water
flowing through the core is mainly the activation product nitrogen-16,
formed by neutron capture from oxygen. N-16 has a half-life on only 7
seconds but produces high-energy gamma radiation during decay.
Reactor power ranges from 10 MWt (in a prototype) up to 200 MWt in
the larger submarines and 300 MWt in surface ships such as the Kirov-class battle cruisers.
The smallest nuclear submarines are the French Rubis-class
attack subs (2600 dwt) in service since 1983, and these have a 48 MW
integrated PWR reactor from Technicatome which is variously reported as
needing no refuelling for 30 years, or requiring refuelling every seven
years. The French aircraft carrier Charles de Gaulle (38,000
dwt), commissioned in 2000, has two K15 integrated PWR units driving 61
MW Alstom turbines and the system can provide 5 years running at 25
knots before refuelling. The Le Triomphant class of ballistic
missile submarines (14,335 dwt submerged - the last launched in 2008)
uses these K15 naval PWRs of 150 MWt and 32 shaft MW with pump-jet
propulsion. The Barracuda class (4765 dwt) attack submarines,
will have hybrid propulsion: electric for normal use and pump-jet for
higher speeds. Areva TA (formerly Technicatome) will provide six
reactors apparently of only 50 MWt and based on the K15 for the Barracuda submarines, the first to be commissioned in 2017. As noted above, they will use low-enriched fuel.
French integrated PWR system for submarine
(steam generator within reactor pressure vessel)
(steam generator within reactor pressure vessel)
British Vanguard class ballistic missile submarines (SSBN)
of 15,900 dwt submerged have a single PWR2 reactor with two steam
turbines driving a single pump jet of 20.5 MW. New versions of this with
"Core H" will require no refuelling over the life of the vessel*. UK Astute
class attack subs of 7400 dwt submerged have a modified (smaller) PWR2
reactor driving two steam turbines and a single pump jet reported as
11.5 MW, and are being commissioned from 2010. In March 2011 a safety
assessment of the PWR2 design was released showing the need for safety
improvement, though they have capacity for passive cooling to effect
decay heat removal. The PWR3 for the Vanguard replacement will be
largely a US design.
* Rolls Royce claims that the Core H PWR2 has six
times the (undisclosed) power of its original PWR1 and runs four times
as long. The Core H is Rolls Royce's sixth-generation submarine reactor
core.
Russia's main submarine power plant is the OK-650 PWR. It uses
20-45% enriched fuel to produce 190 MW. The19,400 tonne Oscar-II class
and 34,000 tonne Typhoon class (NATO name, Akula-class in Russia)
ballistic missile subs (SSBN) have two of these reactors with steam
turbines together delivering 74 MW, and its new 24,000 t Borei-class
ballistic missile sub along with Akula-(Russia: Shchuka-class), Mike-
and Sierra-class attack subs (SSN) have a single OK-650 unit powering a
32 MW steam turbine. The Borei-class is the first Russian design to use
pump-jet propulsion. (displacements: submerged). A 5th generation naval
reactor is reported to be a super-critical type (SCWR) with single steam
circuit and expected to run 30 years without refuelling. A full-scale
prototype was being tested early in 2013.
Russia's large Arktika class icebreakers use two OK-900A
(essentially KLT-40) nuclear reactors of 171 MW each with 241 or 274
fuel assemblies of 45-75% enriched fuel and 3-4 year refuelling
interval. They drive steam turbines and each produces up to 33 MW at the
propellers, though overall power is 54 MW. The two Tamyr class icebreakers have a single 171 MW KLT-40 reactor giving 35 MW propulsive power. Sevmorput
uses one 135 MW KLT-40 unit producing 32.5 MW propulsive, and all those
use 90% enriched fuel. (The now-retired Lenin's first OK-150 reactors
used 5% enriched fuel but were replaced by OK-900 units with 45-75%
enriched fuel.) Most of the Arktika-class vessels have had operating
life extensions based on engineering knowledge built up from experience
with Arktika itself. It was originally designed for 100,000 hours of
reactor life, but this was extended first to 150,000 hours, then to
175,000 hours. In practice this equated to a lifespan of eight extra
years of operation on top of the design period of 25. In that time,
Arkitka covered more than 1 million nautical miles.
For the next LK-60 generation of Russian icebreakers, OKBM Afrikantov
is developing a new reactor – RITM-200 – to replace the current KLT
design. Under Project 22220 this is an integral 175 MWt PWR with
inherent safety features and using low-enriched uranium fuel. Refueling
is every seven years, over a 40-year lifespan. Two reactors drive two
turbine generators and then three electric motors powering the
propellers, producing 60 MW propulsive power. The first icebreaker to be
equipped with these is due to start construction in 2013. For floating
nuclear power plants (FNPP, see below) a single RITM-200 would replace
twin KLT-40S (but yield less power).
The KLT-40S is a 4-loop version of the icebreaker reactor for
floating nuclear power plants which runs on low-enriched uranium
(<20%) and has a bigger core (1.3 m high instead of 1.0 m) and
shorter refueling interval: 3 to 4.5 years. A variant of this is the
KLT-20, specifically designed for FNPP. It is a 2-loop version with same
enrichment but 10-year refueling interval.
OKBM has supplied 460 nuclear reactors for the Russian navy, and these have operated more than 6500 reactor-years.
India's Arihant (6000 dwt) has an 85 MWe PWR using 40%
enriched uranium driving one or two 35 MW steam turbines. It has 13
fuel assemblies each with 348 fuel rods, and was built indigenously.
The reactor went critical in August 2013. A 20 MW prototype unit had
operated for several years from 2003.
Brazil's navy is proposing to build an 11 MW prototype reactor by
2014 to operate for about eight years, with a view to a full-sized
version using low-enriched uranium being in a submarine to be launched
in 2021.
Dismantling decommissioned nuclear-powered submarines has become a
major task for US and Russian navies. After defuelling, normal practice
is to cut the reactor section from the vessel for disposal in shallow
land burial as low-level waste (the rest being recycled normally). In
Russia the whole vessels, or the sealed reactor sections, sometimes
remain stored afloat indefinitely, though western-funded programs are
addressing this and all decommissioned submarines are due to be
dismantled by 2012. In 2009 Rosatom said that by late 2010, 191 out of
198 decommissioned Russian submarines would be dismantled.
Marine reactors used for power supply, Floating Nuclear Power Plants
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.
Between 1967 and 1976 an ex-army US Liberty ship of about 12,000 tonnes built in 1945, the Sturgis (but renamed SS Green Port)
functioned as a Floating Nuclear Power Plant, designation MH-1A,
moored on Gatun Lake, Panama Canal Zone. It had a 45 MWt/ 10 MWe (net)
PWR which provided power to the Canal Zone. The propulsion unit of the
original ship was removed and the entire midsection replaced with a 350
t steel containment vessel and concrete collision barriers. The
containment vessel contained not only the reactor unit itself but the
primary and secondary coolant circuits and electrical systems for the
reactor.
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, but the
order was cancelled in 1978. By the time NRC approval was granted about
1981 for building up to 8 plants, there were no customers and
Westinghouse closed down its OPS division. Westinghouse and Babcock
& Wilcox are reported to be revisiting the concept.
Russia has under construction at St Petersburg the first of a series
of floating power plants for their northern and far eastern territories.
Two OKBM KLT-40S reactors derived from those in icebreakers, but with
low-enriched fuel (less than 20% U-235), are mounted on a 21,500 tonne,
144 m long barge. Refuelling interval is 3-4 years on site, and at the
end of a 12-year operating cycle the whole plant is returned to a
shipyard for a 2-year overhaul and storage of used fuel, before being
returned to service. See also Russia NP paper.
Future prospects
With increasing attention being given to greenhouse gas emissions
arising from burning fossil fuels for international air and marine
transport and the excellent safety record of nuclear powered ships, it
is quite conceivable that renewed attention will be given to marine
nuclear powered ships, it is likely that there will be renewed interest
in marine nuclear propulsion. The world's merchant shipping is reported
to have a total power capacity of 410 GWt, about one third that of world
nuclear power plants.
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 2010 Babcock International's marine division completed a study on
developing a nuclear-powered LNG tanker (which requires considerable
auxiliary power as well as propulsion). The study indicated that
particular routes and cargoes lent themselves well to the nuclear
propulsion option, and that technological advances in reactor design and
manufacture had made the option more appealing.
In November 2010 the British Maritime classification society Lloyd's
Register embarked upon a two-year study with US-based Hyperion Power
Generation, British vessel designer BMT Group, and Greek ship operator
Enterprises Shipping and Trading SA "to investigate the practical
maritime applications for small modular reactors. The research is
intended to produce a concept tanker-ship design," based on a 70 MWt
reactor such as Hyperion's. Hyperion has a three-year contract with the
other parties in the consortium, which plans to have the tanker design
certified in as many countries as possible. The project includes
research on a comprehensive regulatory framework led by the
International Maritime Organisation (IMO), and supported by the
International Atomic Energy Agency (IAEA) and regulators in countries
involved. In response to its members' interest in nuclear propulsion
Lloyd's Register has recently 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. Nuclear ships are currently the
responsibility of their own countries, but none are involved in
international trade. Lloyds expects to "see nuclear ships on specific
trade routes sooner than many people currently anticipate."
The UN's IMO adopted a code of safety for nuclear merchant ships,
Resolution A.491(XII), in 1981, which is still extant and could be
updated. Also Lloyd's Register has maintained a set of provisional rules
for nuclear-propelled merchant ships, which it has recently revised.
Nuclear power seems most immediately promising for the following:
- Large bulk carriers that go back and forth constantly on few routes between dedicated ports – eg China to South America and NW Australia. They could be powered by a reactor delivering 100 MW thrust.
- Cruise liners, which have demand curves like a small town. A 70 MWe unit could give base-load and charge batteries, with a smaller diesel unit supplying the peaks.
- Nuclear tugs, to take conventional ships across oceans
- Some kinds of bulk shipping, where speed is essential.
Sources:
Jane's Fighting Ships, 1999-2000 edition;
J Simpson 1995, Nuclear Power from Underseas to Outer Space, American Nuclear Society
The Safety of Nuclear Powered Ships, 1992 Report of NZ Special Committee on Nuclear Propulsion
Bellona 1996, The Russian Northern Fleet and Civil Nuclear Powered Vessels (on web)
Bellona: http://www.bellona.org/subjects/Russian_nuclear_naval_vessels
http://spb.org.ru/bellona/ehome/russia/nfl/nfl2-1.htm
http://spb.org.ru/bellona/ehome/russia/nfl/nfla.htm
Rawool-Sullivan et al 2002, Technical and proliferation-related aspects of the dismantlement of Russian Alfa-class submarines, Nonproliferation Review, Spring 2002.
Thompson, C 2003, Recovering the Kursk, Nuclear Engineering Int'l, Dec 2003.
Mitenkov F.M. et al 2003, Prospects for using nuclear power systems in commercial ships in Northern Russia, Atomic Energy 94, 4
Jane's Fighting Ships, 1999-2000 edition;
J Simpson 1995, Nuclear Power from Underseas to Outer Space, American Nuclear Society
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