The scope of nuclear civil vessels includes the following three types of vessels:

  1.  Nuclear Merchant Ships;
  2.  Nuclear Icebreakers; and
  3.  Nuclear Cruise Ships.

This chapter is dedicated to Nuclear Icebreakers.


An icebreaker ship requires the following three main faculties that most normal ships lack:

  1. A strengthened hull;
  2. An ice-clearing shape; and
  3. The power to push through ice-covered waters.

Icebreakers ships designed to cruise on ice-covered water by breaking through the ice with their strong, heavy, steel bows. The main objective for constructing icebreakers was to keep routes open for commerce where either seasonal or permanent ice conditions exit.


An icebreaker ship powered by nuclear to break floating ice is known as nuclear icebreaker and nuclear icebreakers are far more powerful than their diesel powered counterparts. Icebreakers were constructed by Russia primarily to aid shipping in the frozen Arctic waterways in the north of Siberia.

Just to appreciate the severity of the conditions, during the winter, the ice along the northern seaways varies in thickness from 1.2 to 2.0 metres (3.9 to 6.5 feet). The ice in central parts of the Arctic Ocean is on average 2.5 metres (8.2 ft) thick. Nuclear-powered icebreakers can force through this ice at speeds up to 10 knots (19 km/h 12 mph). In ice-free- waters the maximum speed of the nuclear-powered icebreakers is as much as 21 knots (35 km/h, 24 mph).

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 refueling difficulties for other types of vessels, are significant factors. The nuclear fleet has increased Arctic navigation from 2 to 10 months per year, and in the Western Arctic, to year-round. Greater use of the icebreaker fleet is expected with developments on the Yamal Peninsula and further east.

The icebreaker reactors are bigger than the reactors in nuclear submarines. The fuel used in OK-900A reactors is enriched to 45-75 percent uranium-235, and each reactor core holds 241 fuel assemblies, including 200 kg of uranium-235. The fuel in KLT-40 reactors is enriched up to 90 percent; it too contains 241 fuel assemblies, with a total of approximately 150kg of uranium-235. Fuel is replaced every three to four years, and it takes approximately 45 days to refuel a nuclear-powered icebreaker. Generally, one reactor acts as the primary propulsion, and the second operates at low power. Water in the pressurized closed water circuit is heated to 300 to 400 degrees Celsius to produce steam. The steam enters a system of four steam generators per reactor core. These generators run the turbines, which run the propellers. Because it is a closed water circuit, this water is recirculated to the steam generators. The cooling system of the icebreaker reactors is specially designed to use cold Arctic seawater.

Russia has the most powerful icebreaker fleet in the world, as well as unique experience in the design, construction and operation of such ships. Russian experience with nuclear powered Arctic ships totals about 300 reactor-years in 2009. The Murmansk Shipping Company (MSC) for the Ministry of Transport previously operated Russia’s fleet of nuclear icebreakers. However, in August 2008 responsibility was transferred to Rosatom by presidential decree and the agency is now tasked with both making the fleet profitable and addressing legacy issues such as radioactive waste and the decommissioning of old ships.

2.1      NS Icebreaker Lenin:

The nuclear icebreaking fleet was developing nearly in parallel with domestic nuclear power. The decision to build the first nuclear icebreaker was taken on November 20, 1953, and the ship’s keel laying took place at Admiralteyskiy Zavod (shipyard) in Leningrad on August 24, 1956. The icebreaker Lenin was undergone sea trials in the Gulf of Finland in September 1959 and was officially accepted for service on December 3, 1959. It was launched on December 05, 1959. The 510 manufacturing plants and organizations all over the country were involved in its building. Vessel particulars include:

  • Length: 134 metres;
  • Beam: 27.6 metres;
  • Height: 16.1 metres;
  • Max speed: 18 knots,
  • Displacement: 16,000 metric tons without ballast; and
  • Propulsion by three DC motors driving three screw propellers.


NS Lenin was both the world’s first nuclear powered surface ship and the first nuclear powered civilian vessel. The first nuclear propulsion unit (OK-150) on Lenin had three identical pressurized water reactors (PWR) with a maximum heat output of 90 MWt. The shaft power was 44, 000 horsepower. Enriched uranium was used as fuel (the content of U-235 was equivalent 85 kg), and distillate water was used as a moderator and for heat transfer. The reactor core was 1.6 meters high and measured one meter in diameter. The core consisted of 7,704 fuel pins in 219 fuel assemblies.

There have been two accidents, the first took place in February 1965, when Lenin was undergoing repairs and refueling. The vessel sustained severe mechanical damages to the fuel assemblies, some of which were broken in two pieces, and were detected during the unloading of fuel from reactor number two. About 95 spent nuclear fuel assemblies were transferred to the nuclear service ship Lepse and unloading was halted. After investigations as to why the spent nuclear fuel assemblies were deformed, it was established that the nuclear reactor operators had made an error that left the reactor core without cooling water.  The partial deformation of the fuel assemblies had occurred due to overheating of the reactor core. About 60 percent of the assemblies were damaged.

The second accident aboard the Lenin took place in 1967, when the pipe system of the third circuit sprung a leak following the loading of fresh nuclear fuel. The second accident resulted in one of the three OK-150 reactors being damaged beyond repair. All three reactors were removed, and replaced by two OK-900 reactors; the ship returned to service in 1970. The Lenin was taken out of operation in November 1989 and laid up at Atomflot, the base for nuclear powered icebreakers in the Murmansk Fiord before it was converted to a museum ship.

The vessel was initially fitted with three OK-150 pressurized water reactors producing 90 MW each. Due to operational problems including a partial core melt in 1965, two OK-900 units producing 171 MW each replaced the units. Remained in service for 30 years in the Northern Sea Route, breaking ice for container ships to navigate. During this period, escorted 3,741 transport ships. Voyage covered 654,400 nautical miles, including 560,600 nautical miles in ice.


2.2      Arktika-Class Nuclear Icebreakers:

The nuclear icebreakers of the Arktika class are used to force through the ice for the benefit of cargo ships and other vessels along the northern seaway. The northern seaway comprises the eastern part of the Barents Sea, the Petchora Sea, the Kara Sea, the Laptev Sea and the Eastern Siberian Sea to the Bering Strait. Important ports on the northern seaway are, among others, Dikson, Tiksi, and Pevek.

In addition to cruising on ice-covered water, the icebreakers have also been used for a number of scientific expeditions in the Arctic. On August 17, 1977, the NS Arktika was the first surface vessel in the world to reach the North Pole.  Since 1989, some icebreakers have been used for Arctic tourism cruises.


There are six icebreakers classified as Arktika class icebreakers that represent the bulk of the Russian nuclear icebreaker fleet:

  • NS Arktika launched in 1959;
  • NS Sibir launched in 1977;
  • NS Rossiya launched in 1985;
  • NS Sovetskiy Soyuz launched in 1990;
  • NS Yamal launched in 1993; and
  • NS 50 Let Probedy launched in 1993.


Since these icebreakers have been built over a period of thirty years, there is a fair bit of variation between ships of the class; thus, specifications are listed as a range of values. In general, the newer ships are larger, faster, and require smaller crews.


  • Length: 148 m to 159 m (approximately 136 m at the waterline);
  • Beam: 30 m (28 m at the waterline);
  • Draft: approximately 11.08 m.;
  • Height (keel to masthead): approximately 55 m;
  • Displacement: 23,000 to 25,000 tons;
  • Maximum speed: 18 to 22 knots;
  • Cruising speed: approximately 18 to 20 knots;
  • Crew: 138 to over 200;
  • Passengers: approximately 100;
  • Reactors: 2 OK-900A, 171 megawatt each;
  • Propulsion: 3 propellers totaling approximately 75,000 hp;
  • Maximum Ice Thickness: 2 to 2.8 m; and
  • Endurance: 7.5 months at sea, 4 years between refuelings.


Arktika-class icebreakers have a double hull, with the outer hull being approximately 48 mm thick at the ice-breaking areas and 25 mm thick elsewhere. There is water ballast between the inner and outer hulls that can be shifted to aid icebreaking. Icebreaking is also assisted by an air bubbling system, which can deliver 24 m of air from jets 9 m below the surface. Some ships have polymer-coated hulls to reduce friction.  Arktika-class ships can break ice while making way either forwards or backwards. These ships must cruise in cold water, in order to cool their reactors. As a result, they cannot pass through the tropics to undertake voyages in the Southern Hemisphere.  Although they have two reactors, normally only one is used to provide power, with the other being maintained in a standby mode.


Some ships carry one or two helicopters and several Zodiac boats.  Radio and satellite systems can include navigation, telephone, fax, and email capabilities.

Most nuclear powered icebreakers in the Russian service today have a swimming pool, a sauna, a cinema, and a gymnasium.  In the restaurants aboard there is a bar and facilities for live music performances. Some also have a library and at least one has a volleyball court.

The Arktika was retired for several years, but was repaired in the late 1990s.

On April 9, 2007, a fire broke out on the Arktika. The fire caused minor damage to three cabins and knocked out an electricity-distribution panel. The nuclear reactor was not damaged. There were no injuries. The icebreaker was in the Kara Sea when the blaze erupted, and was sent to Murmansk.  The ship was officially taken out of service in October 2008.

The vessel served shipping routes in the Arctic Ocean and the seas north of Russia from April 1975, powered by two 171 MWt pressurized water reactors which provided 54 MW at its propellers. In 2000, it was the first civilian ship to operate for a whole year without docking.

Most of the Arktika-class vessels have had operating life extensions based on engineering knowledge built up from experience with Arktika itself. Nuclear.Ru reported that the ship 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, it covered more than 1 million nautical miles.

Apart from that, it will not sail again, the future for Arktika is uncertain. Docked at an AtomFlot facility, it will initially provide an engineering base to study further life extension options for its sister vessels. It will ultimately be dismantled under a schedule to be determined by the Rosatom agency, which sets the strategy for all Russian nuclear programs.

The NS Sibir is presently not in operation and stationed at Atomflot for extensive repair. Among other things, the nuclear reactors and turbine generators are to be upgraded, as these do not satisfy the safety standards established for newer nuclear powered icebreakers. The NS Sibir might not ever come into operation again due to the operational economics. Unless there is a significant increase of transport in the Arctic, it will not be profitable to operate all six Arktika-class icebreakers. It is to be expected that the oldest icebreakers would be the first ones to be taken out of operation.

The NS Rossiya carries two helicopters. Rossiya was used to transport an expedition of around 40 West Germans to the North Pole in the summer of 1990; this may have been the first non-communist charter of a nuclear icebreaker. Rossiya was in refit as of December 2004.

The NS Sovetskiy Soyuz was trapped in ice for three days in 1998. In 2004, it was one of three icebreakers used for an Arctic ice core expedition intended to research climate change and global warming.  One tourism operator lists it as being possibly used for North Pole cruises.

The NS Yamal is mostly used for tourism and scientific expeditions. It has 50 passenger cabins and suites, and carries one helicopter. The crew is 150, including 50 officers and engineers. Yamal was the 12th surface ship ever to reach the North Pole.

The NS 50 Lyet Pobyedi is the final Arktika class ship. It was launched from the shipyard at Saint Petersburg on December 29, 1993 as the NS Ural, and delivered to Murmansk in 1994.  It was later renamed and not actually completed and commissioned until 2006 due to funding delays. The crew is expected to normally number 138 persons. It has an environmental waste processing module added to the hull, which accounts for 9 m of the ship’s 159 m length; this makes it the largest of the Arktika class and the largest nuclear powered icebreaker in the world. It carries two Ka-32 helicopters. It entered service on April 2, 2007.

2.3                  Taymyr-Class Nuclear Icebreakers:

The Finnish shipbuilder Wartsila built many icebreakers for the Soviet Union and provided many advances in design during the years of development of conventionally powered icebreakers. Recently, these two technologies merged to develop Taymyr-class, shallow-draft polar icebreakers built in Helsinki New Shipyard in Finland and the nuclear reactors were installed at Leningrad Baltic Shipyard in the Soviet Union after delivering from Finland.


The Russian nuclear-powered icebreaker fleet includes two third-generation Taymyr-class river icebreakers – Taymyr (Also known as Taimyr) and Vayguch (Also known as Vaigach). Taimyr class specifications:

  • Length: 150.2 m (Taimyr), 151.8 m (Vaiguch)
  • Beam: 29.2 m
  • Draft: 8.0 m
  • Height: 15.2 m keel to main deck, 8 stories from main deck to bridge
  • Displacement: 20,000 tons
  • Speed: 18.5 knots
  • Crew: 120 to 138
  • Reactors: One KLT-40M reactor producing 135 MW
  • Propulsion: 3 propellers totaling 52,000 hp

The bow hull plating is approximately 32 mm thick. As of December 2004, both vessels were undergoing refitting.

Like NS Lenin and NS Arktika, icebreaker Taymyr is a turbo-electric nuclear ship with a three-shaft propulsion plant. However, main power plant incorporates one reactor instead of two that generates steam for two steam turbines being a drive for two main ac generators. A principle of single electric power system is realized on the icebreaker. The 32.5-MWe single reactor ships use a single modified KLT-40M reactor each. The icebreakers Taymyr and Vayguch have special devices to control the exact running of the turbines within the plant receiving the steam from the nuclear reactor. The main activity is continuous monitoring of the turbine shaft frequency.  A personal computer based system gives an alarm if there is a significant deviation.

Taymyr and Vayguch are to be withdrawn from service in 2015 and 2016, according to estimates made in 2000. In 2008, one source estimated that the Taymyr could remain in operation until 2013 and the Vayguch until 2014. Reactor and ship designers were investigating the feasibility of extending reactor service life from 100,000 hours to 150,000 hours, corresponding roughly to 10 additional years of icebreaker operation. Most of the Arktika-class vessels have had operating life extensions based on engineering knowledge built up from experience with Arktika itself.

2.4      Future Plans for Nuclear Icebreakers:

Russian planners foresee a need for six to ten new nuclear-powered icebreakers in the next 20 years.

Russia is planning to start building new icebreakers after 2010. In June 2008 the head of the state nuclear corporation Rosatom, Sergei Kiriyenko, said “It is important to not only use the existing fleet of icebreakers, but also to build new ships, and the first nuclear icebreaker of a new generation will be built by 2015. This should be an icebreaker capable of moving in rivers and seas,” he said.


  1. Wikipedia:      Nuclear-Powered Icebreakers;
  2. Bellona: Nuclear Icebreaker      Lenin;
  3. State Atomic Energy      Corporation “Rosatom”;
  4. World Nuclear      Association: Nuclear Power in Russia;
  5. Russian Arktika Class      Nuclear Powered Icebreakers;
  6. Nuclear Powered Icebreaker;
  7. Russia: Nuclear-Powered Icebreakers;  and
  8. Global Security.
  • This chapter was published on “Inuitech – Intuitech Technologies for Sustainability”
    on October 23, 2011; and
  • This chapter was updated on 14 June 2020

Chapter 12