Pressurized water reactor
Pressurized water reactors constitute the large majority of the world's nuclear power plants and are one of three types of light water reactor, the other types being boiling water reactors and supercritical water reactors. In a PWR, the primary coolant is pumped under high pressure to the reactor core where it is heated by the energy released by the fission of atoms; the heated water flows to a steam generator where it transfers its thermal energy to a secondary system where steam is generated and flows to turbines which, in turn, spin an electric generator. In contrast to a boiling water reactor, pressure in the primary coolant loop prevents the water from boiling within the reactor. All LWRs use ordinary water as both neutron moderator. PWRs were designed to serve as nuclear marine propulsion for nuclear submarines and were used in the original design of the second commercial power plant at Shippingport Atomic Power Station. PWRs operating in the United States are considered Generation II reactors.
Russia's VVER reactors are similar to U. S. PWRs. France operates many PWRs to generate the bulk of its electricity. Several hundred PWRs are used for marine propulsion in aircraft carriers, nuclear submarines and ice breakers. In the US, they were designed at the Oak Ridge National Laboratory for use as a nuclear submarine power plant with a operational submarine power plant located at the Idaho National Engineering Lab. Follow-on work was conducted by Westinghouse Bettis Atomic Power Laboratory; the first purely commercial nuclear power plant at Shippingport Atomic Power Station was designed as a pressurized water reactor, on insistence from Admiral Hyman G. Rickover that a viable commercial plant would include none of the "crazy thermodynamic cycles that everyone else wants to build."The United States Army Nuclear Power Program operated pressurized water reactors from 1954 to 1974. Three Mile Island Nuclear Generating Station operated two pressurized water reactor plants, TMI-1 and TMI-2; the partial meltdown of TMI-2 in 1979 ended the growth in new construction of nuclear power plants in the United States for two decades.
The pressurized water reactor has three new Generation III reactor evolutionary designs: the AP-1000, VVER-1200, ACPR1000+, APR1400. Nuclear fuel in the reactor pressure vessel is engaged in a fission chain reaction, which produces heat, heating the water in the primary coolant loop by thermal conduction through the fuel cladding; the hot primary coolant is pumped into a heat exchanger called the steam generator, where it flows through hundreds or thousands of small tubes. Heat is transferred through the walls of these tubes to the lower pressure secondary coolant located on the sheet side of the exchanger where the coolant evaporates to pressurized steam; the transfer of heat is accomplished without mixing the two fluids to prevent the secondary coolant from becoming radioactive. Some common steam generator arrangements are single pass heat exchangers. In a nuclear power station, the pressurized steam is fed through a steam turbine which drives an electrical generator connected to the electric grid for transmission.
After passing through the turbine the secondary coolant is cooled condensed in a condenser. The condenser converts the steam to a liquid so that it can be pumped back into the steam generator, maintains a vacuum at the turbine outlet so that the pressure drop across the turbine, hence the energy extracted from the steam, is maximized. Before being fed into the steam generator, the condensed steam is sometimes preheated in order to minimize thermal shock; the steam generated has other uses besides power generation. In nuclear ships and submarines, the steam is fed through a steam turbine connected to a set of speed reduction gears to a shaft used for propulsion. Direct mechanical action by expansion of the steam can be used for a steam-powered aircraft catapult or similar applications. District heating by the steam is used in some countries and direct heating is applied to internal plant applications. Two things are characteristic for the pressurized water reactor when compared with other reactor types: coolant loop separation from the steam system and pressure inside the primary coolant loop.
In a PWR, there are two separate coolant loops, which are both filled with demineralized/deionized water. A boiling water reactor, by contrast, has only one coolant loop, while more exotic designs such as breeder reactors use substances other than water for coolant and moderator; the pressure in the primary coolant loop is 15–16 megapascals, notably higher than in other nuclear reactors, nearly twice that of a boiling water reactor. As an effect of this, only localized boiling occurs and steam will recondense promptly in the bulk fluid. By contrast, in a boiling water reactor the primary coolant is designed to boil. Light water is used as the primary coolant in a PWR. Water enters through the bottom of the reactor's core at about 548 K and is heated as it flows upwards through the reactor core to a temperature of about 588 K; the water remains liquid despite the high temperature due to the high pressure in the primary coolant loop around 155 bar. In water, the critical point occurs at 22.064 MPa.
Pressure in the primary circuit is maintained by a pressurizer, a separate vessel, conne
The Soviet Navy was the naval arm of the Soviet Armed Forces. Referred to as the Red Fleet, the Soviet Navy was a large part of the Soviet Union's strategic plan in the event of a conflict with opposing super power, the United States, the North Atlantic Treaty Organization, or another conflict related to the Warsaw Pact of Eastern Europe; the influence of the Soviet Navy played a large role in the Cold War, as the majority of conflicts centered on naval forces. The Soviet Navy was divided into four major fleets: the Northern, Black Sea, Baltic Fleets; the Caspian Flotilla was a smaller force operating in the land-locked Caspian Sea. Main components of the Soviet Navy included Soviet Naval Aviation, Naval Infantry, Coastal Artillery. After the dissolution of the Soviet Union in 1991, Russia inherited the largest part of the Soviet Navy and reformed it into the Russian Navy, with smaller parts becoming the basis for navies of the newly independent post-Soviet states; the Soviet Navy was based on a republican naval force formed from the remnants of the Imperial Russian Navy, completely destroyed in the two Revolutions of 1917 during World War I, the following Russian Civil War, the Kronstadt rebellion in 1921.
During the revolutionary period, Russian sailors deserted their ships at will and neglected their duties. The officers were dispersed and most of the sailors walked off and left their ships. Work stopped in the shipyards; the Black Sea Fleet fared no better than the Baltic. The Bolshevik revolution disrupted its personnel, with mass murders of officers. At the end of April 1918, Imperial German troops moved along the Black Sea coast and entered Crimea and started to advance towards the Sevastopol naval base; the more effective ships were moved from Sevastopol to Novorossiysk where, after an ultimatum from Germany, they were scuttled by Vladimir Lenin's order. The ships remaining in Sevastopol were captured by the Germans and after the Armistice of 11 November 1918 on the Western Front which ended the War, additional Russian ships were confiscated by the British. On 1 April 1919, during the ensuing Russian Civil War when Red Army forces captured Crimea, the British Royal Navy squadron had to withdraw, but before leaving they damaged all the remaining battleships and sank thirteen new submarines.
When the opposing Czarist White Army captured Crimea in 1919, it rescued and reconditioned a few units. At the end of the civil war, Wrangel's fleet, a White flotilla, moved south through the Black Sea, Dardanelles straits and the Aegean Sea to the Mediterranean Sea to Bizerta in French Tunisia on the North Africa coast, where it was interned; the first ship of the revolutionary navy could be considered the rebellious Imperial Russian cruiser Aurora, built 1900, whose crew joined the communist Bolsheviks. Sailors of the Baltic fleet supplied the fighting force of the Bolsheviks led by Vladimir Lenin and Leon Trotsky during the October Revolution of November 1917 against the democratic provisional government of Alexander Kerensky established after the earlier first revolution of February against the Czar; some imperial vessels continued to serve after the revolution, albeit with different names. The Soviet Navy, established as the "Workers' and Peasants' Red Fleet" by a 1918 decree of the new Council of People's Commissars, installed as a temporary Russian revolutionary government, was less than service-ready during the interwar years of 1918 to 1941.
As the country's attentions were directed internally, the Navy did not have much funding or training. An indicator of its reputation was that the Soviets were not invited to participate in negotiations for the Washington Naval Treaty of 1921–1922, which limited the size and capabilities of the most powerful navies - British, Japanese, Italian; the greater part of the old fleet was sold by the Soviet government to post-war Germany for scrap. In the Baltic Sea there remained only three much-neglected battleships, two cruisers, some ten destroyers, a few submarines. Despite this state of affairs, the Baltic Fleet remained a significant naval formation, the Black Sea Fleet provided a basis for expansion. There existed some thirty minor-waterways combat flotillas. During the 1930s, as the industrialization of the Soviet Union proceeded, plans were made to expand the Soviet Navy into one of the most powerful in the world. Approved by the Labour and Defence Council in 1926, the Naval Shipbuilding Program included plans to construct twelve submarines.
Beginning 4 November 1926, Technical Bureau Nº 4, under the leadership of B. M. Malinin, managed the submarine construction works at the Baltic Shipyard. In subsequent years, 133 submarines were built to designs developed during Malinin's management. Additional developments included the formation of the Pacific Fleet in 1932 and the Northern Fleet in 1933; the forces were to be built around a core of powerful Sovetsky Soyuz-class battleships. This building program was only in its initial stages by the time the German invasion forced its suspension in 1941; the Soviet Navy had some minor action
Project 971 Щука-Б is a nuclear-powered attack submarine first deployed by the Soviet Navy in 1986. The class is known under the name Bars. There are four sub-classes or flights of Shchuka, consisting of the original seven Akula Is, commissioned between 1984 and 1990; the Russians call all of the submarines Shchuka-B, regardless of modifications. Some potential for confusion may exist, as the name Akula was used by the Soviets for a different submarine, the Projekt 941, known in the West as the Typhoon class. By contrast, the Projekt 971 was named Shchuka-B by the Soviets but designated as the "Akula class" by the West after the name of the lead ship, K-284; the launch of the first submarine in 1985, according to defense analyst Norman Polmar, "shook everyone up", as Western intelligence agencies had not expected the Soviet Union to produce such a boat for another ten years. The Akula incorporates a double hull system composed of an inner pressure hull and an outer "light" hull; this allows more freedom in the design of the exterior hull shape, resulting in a submarine with more reserve buoyancy than its western analogs.
This design requires more power than single-hull submarines because of the greater wetted surface area, which increases drag. The distinctive "bulb" or "can" seen on top of the Akula's rudder houses its towed sonar array, when retracted. Most Akulas have the SOCKS hydrodynamic sensors, which detect changes in salinity, they are located on the leading edge of the sail, on the outer hull casing in front of the sail and on the bottom of the hull forward of the sail. All Akulas have two T-shaped doors on the aft bottom of the hull, on either side; these are where the OK-300 auxiliary propulsion devices are located, which can propel the submarine at up to 5 knots. Akulas are armed with four 533 mm torpedo tubes which can use Type 53 torpedoes or the SS-N-15 Starfish missile, four 650 mm torpedo tubes which can use Type 65 torpedoes or the SS-N-16 Stallion missile; these torpedo tubes are arranged in two rows of four tubes each. Improved Akulas, Akula IIs have an additional six 533 mm torpedo tubes mounted externally, capable of launching up to 6 decoys each.
The external tubes are mounted outside the pressure hull in one row, above the torpedo tubes, can only be reloaded in port or with the assistance of a submarine tender. The 650 mm tubes can be fitted with liners to use the 533 mm weaponry; the submarine is able to use its torpedo tubes to deploy mines. As with many Soviet/Russian craft, information on the status of the Akula-class submarines is sparse, at best. Information provided by sources varies widely. Of the seven original Akulas, only three are known to still be in service; these boats are equipped with MGK-500 Skat sonar system. The lead boat of the class, K-284 Akula was decommissioned in 2001 to help save money in the cash-strapped Russian Navy. K-322 Kashalot and K-480 Bars are in reserve. K-480 Bars was put into reserve in 1998, is being dismantled in February 2010. Pantera returned to service in January 2008 after a comprehensive overhaul. All were retrofitted with the SOCKS hydrodynamic sensors. All submarines before K-391 Bratsk have reactor coolant scoops that are similar to the ones of the Typhoon-class SSBNs, long and tubular.
Bratsk and subsequent submarines have reactor coolant scoops similar to the short ones on the Oscar IIs. The six Akulas of this class are all thought to be in service, they are quieter than the original Akulas. The MGK-500 sonar is upgraded to MGK-501 Skat-MS. Sources disagree as to whether construction of this class has been suspended, or if there are a further two units planned. Improved Akula-I Hulls: K-328 Leopard, K-461 Volk, K-154 Tigr, K-419 Kuzbass, K-295 Samara and K-152 Nerpa; these submarines are much quieter than early Akula class submarines and all have the SOCKS hydrodynamic sensors except Leopard. The Akula-I Improved submarines have six 533 mm decoy launching tubes, they have a different arrangement of limber holes on the outer hull than Akula Is. Nerpa and Iribis have a different rescue chamber in the sail, which can be distinguished by the large dome on the top surface. K-157 Vepr is the only completed Akula II; the Akula II is 3 metres longer and displaces about 700 tons more than the Akula I.
The added space was used for additional quieting measures. The MGK-501 Skat sonar system on Akula-I is replaced to a new MGK-540 Skat-3 sonar system. K-157 Vepr became the first Soviet submarine, quieter than the latest U. S. attack submarines of that time, the improved Los Angeles class. Two of these submarines were used to build the Borei-class SSBNs; the K-335 Gepard is the 14th submarine of the class and the only completed Akula III built for the Russian Navy. It was the first submarine commissioned in the Russian Navy since the Kursk disaster, as a result, its commissioning ceremony was an important morale boost for the Russian Navy with President Vladimir Putin in attendance. There is no NATO classification for the Akula III, it is longer and has a larger displacement compared to the Akula II it has an enlarged sail and a different towed-array dispenser on the vertical fin. Again, more noise reduction methods were employed; the Gep
The Soviet Navy's Project 611 were one of the first Soviet post-war attack submarines. They were as capable as the American GUPPY fleet-boat conversions, they shared a similar sonar arrangement. Like most conventional submarines designed 1946-1960, their design was influenced by the German Type XXI U-boat of the World War II era; the first few boats of the class were equipped with twin 57mm and twin 25mm anti-aircraft guns and no snorkels, although the guns were removed and snorkels added soon after the boats entered service. Six were converted in 1956 to become the world's first ballistic missile submarines, one armed with a single R-11FM Scud missile and five others with two Scuds each, they were designated as Project AV 611 and received the NATO reporting name of Zulu V. The missiles were too long to be contained in the boat's hull, extended into the enlarged sail. To be fired, the submarine had to raise the missile out of the sail. Soviet submarine B-67 launched a missile on 16 September 1955.
The Zulus were the basis for the successful Foxtrot-class submarine, which lent their hull to the Golf class of ballistic missile submarine. Twenty-six boats were built overall, entering service from 1952 to 1957, 8 of them in Leningrad and 18 in Severodvinsk, their names were B-61 through B-82 and B-88 through B-91, with most renamed in the 1970s or 1980s. The class received the NATO reporting names Zulu I through Zulu V, the last referring to the five converted missile-firing submarines, it is unclear from references. Most were converted to non-combat uses and scrapped. Gardiner and Chumbley, Conway's all the world's fighting ships 1947-1995, Naval Institute Press, 1996. ISBN 1-55750-132-7. Globalsecurity.org article Deep storm article Zulu Class submarines - Complete Ship List
The Yankee class was a class of Soviet nuclear ballistic missile submarines, constructed from 1967 onward. 34 units were produced under Project 667AU Nalim. 24 were built at Severodvinsk for the Northern Fleet while the remaining 10 built in Komsomolsk-na-Amurye for the Pacific Fleet. Two Northern Fleet units were transferred to the Pacific; the lead unit K-137 Leninets, receiving its honorific name 11 April 1970, two and one half years after being commissioned. The Yankee-class nuclear submarines were the first class of Soviet ballistic missile submarines to have thermonuclear firepower comparable with that of their American and British Polaris submarine counterparts; the Yankee class were quieter in the ocean than were their Hotel-class predecessors, had better streamlining that improved their underwater performance. The Yankee class were quite similar to the Polaris submarines of the U. S. Navy and the Royal Navy; these boats were all armed with 16 submarine-launched ballistic missiles with multiple nuclear warheads as nuclear deterrents during the Cold War, their ballistic missiles had ranges from 1,500–2,500 nautical miles.
The Yankee-class SSBNs served in the Soviet Navy in three oceans: the Atlantic Ocean, the Pacific Ocean, the Arctic Ocean beginning in the 1960s. During the 1970s about three Yankee-class were continually on patrol in a so-called "patrol box" in the Atlantic Ocean just east of Bermuda and off the US Pacific coast; this forward deployment of the SSBNs was seen to balance the presence of American and French nuclear weapons kept in Western Europe and on warships in the surrounding Atlantic Ocean, including the Mediterranean Sea and the Eastern Atlantic. One Yankee-class submarine, K-219, was lost on 6 October 1986 after an fire on board; this boat had been at sea near Bermuda, she sank from loss of buoyancy because of flooding. Four of her sailors died. At least one other boat in this class was involved in a collision with a U. S. Navy nuclear submarine; because of their increasing age, as negotiated in the SALT I treaty, the START I treaty, the START II treaty, that reduced the nuclear armaments of the United States and the Soviet Union, all of the boats of the Yankee class, all Polaris missile and Poseidon missile submarines were disarmed and sent to the nuclear ship scrapyards.
There were eight different versions of the Yankee subs: Yankee I: The baseline configuration, these were ballistic missile submarines that first saw service in 1968. The subs carried 16 SS-N-6 missiles, had 6 torpedo tubes, carried 18 Type 53 torpedoes, they were the first Soviet SSBNs to carry their ballistic missiles within the hull. Yankee II: A single-ship class, this was a Yankee I submarine converted to carry 12 SS-N-17 missiles, the Soviet Navy's first solid-fuelled SLBM; the existence of this individual prototype led to several theories about the Yankee II having a unique role in the Soviet arsenal that justified maintaining a single ship with such a unique weapon. One theory suggested. Subsequently, it was proposed that the SS-N-17 may have had a retargeting capability to allow strikes on aircraft carrier battle groups. Yankee Notch: These converted subs were attack submarines and first appeared in 1983, they incorporated a "notch waisted" center section, which replaced the old ballistic missile compartment, featuring eight 533-millimetre torpedo tubes for up to 40 SS-N-21 missiles or additional torpedoes.
The forward torpedo tubes were retained as well, with some reports suggesting that the vessels may have been able to fire 650 mm Type 65 torpedoes. The emphasis on additional SS-N-21 missile carriage suggested a tactical role for these submarines, or as second-strike nuclear submarines, their configuration was a combination of SALT treaty limitations and a typical Soviet unwillingness to discard any military hardware that might still have some use. The conversion increased the overall length by 12 metres to 141.5 m, with a displacement of up to 11,500 tons submerged. While classed as SSNs, these boats might be considered SSGNs by virtue of their heavy missile armament. Yankee Sidecar Also known as Yankee SSGN, this was another single-ship class converted into an SSGN, it appeared in 1983, carrying 12 SS-NX-24 nuclear-tipped cruise missiles instead of the original ballistic missiles. The SS-NX-24 was an experimental cruise missile, with a supersonic flight regime and twin nuclear warheads, it was meant as a tri-service strategic weapon, thus would have filled a rather different role than the tactically-oriented Oscar-class SSGNs of the same era.
In the end, the missile was not adopted, K-420 became a weapon system without a weapon. It was 13,650 tons displacement, was longer than the Yankee Notch to accommodate the massive cruise missiles. Yankee SSN 16 of this type were converted from the basic Yankee I specification; some were not converted, although they cannot carry ballistic missiles, so they were called Yankee SSNX. They retained only their forward torpedo tubes, with the central missile sections having been removed; some are being scrapped. Yankee Pod The Yankee Pod (also known a
A nuclear submarine is a submarine powered by a nuclear reactor. The performance advantages of nuclear submarines over "conventional" submarines are considerable. Nuclear propulsion, being independent of air, frees the submarine from the need to surface as is necessary for conventional submarines; the large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods of time. Current generations of nuclear submarines never need to be refueled throughout their 25-year lifespans. Conversely, the limited power stored in electric batteries means that the most advanced conventional submarine can only remain submerged for a few days at slow speed, only a few hours at top speed, though recent advances in air-independent propulsion have somewhat ameliorated this disadvantage; the high cost of nuclear technology means that few states have fielded nuclear submarines. Some of the most serious nuclear and radiation accidents to occur have involved Soviet nuclear submarine mishaps.
The idea for a nuclear-powered submarine was first proposed in the United States Navy by the Naval Research Laboratory's Ross Gunn in 1939. Construction of the world's first nuclear powered submarine was made possible by the successful development of a nuclear propulsion plant by a group of scientists and engineers at the Naval Reactors Branch of the Bureau of Ships and the Atomic Energy Commission. In July 1951 the U. S. Congress authorized construction of the first nuclear-powered submarine, under the leadership of Captain Hyman G. Rickover, USN; the Westinghouse Corporation was assigned to build its reactor. After the submarine was completed at the Electric Boat Company, First Lady Mamie Eisenhower broke the traditional bottle of champagne on Nautilus' bow, she was commissioned USS Nautilus, on 30 September 1954. On 17 January 1955, she departed Connecticut to begin sea trials; the submarine was 320 feet long, cost about $55 million. The Soviet Union soon followed the United States in developing nuclear-powered submarines in the 1950s.
Stimulated by the U. S. development of Nautilus, Soviet work on nuclear propulsion reactors began in the early 1950s at the Institute of Physics and Power Engineering, in Obninsk, under Anatoliy P. Alexandrov to become head of the Kurchatov Institute. In 1956, the first Soviet propulsion reactor designed by his team began operational testing. Meanwhile, a design team under Vladimir N. Peregudov worked on the vessel that would house the reactor. After overcoming many obstacles, including steam generation problems, radiation leaks, other difficulties, the first nuclear submarine based on these combined efforts, K-3 Leninskiy Komsomol of the Project 627 Kit class, called a November-class submarine by NATO, entered service in the Soviet Navy in 1958. Nuclear power proved ideal for the propulsion of strategic ballistic missile submarines improving their ability to remain submerged and undetected; the world's first operational nuclear-powered ballistic missile submarine was USS George Washington with 16 Polaris A-1 missiles, which conducted the first SSBN deterrent patrol November 1960 – January 1961.
The Soviets had several SSBs of the Project 629, were only a year behind the US with their first SSBN, ill-fated K-19 of Project 658, commissioned in November 1960. However, this class carried the same three-missile armament as the Golfs; the first Soviet SSBN with 16 missiles was the Project 667A, the first of which entered service in 1967, by which time the US had commissioned 41 SSBNs, nicknamed the "41 for Freedom". At the height of the Cold War five to ten nuclear submarines were being commissioned from each of the four Soviet submarine yards. From the late 1950s through the end of 1997, the Soviet Union, Russia, built a total of 245 nuclear submarines, more than all other nations combined. Today, six countries deploy some form of nuclear-powered strategic submarines: the United States, France, the United Kingdom and India. Several other countries, including Argentina and Brazil, have ongoing projects in different phases to build nuclear-powered submarines. In the United Kingdom, all former and current nuclear submarines of the British Royal Navy have been constructed in Barrow-in-Furness where construction of nuclear submarines continues.
Conqueror is the only nuclear-powered submarine to have engaged an enemy ship with torpedoes, sinking the cruiser ARA General Belgrano with two Mark 8 torpedoes during the 1982 Falklands War. The main difference between conventional submarines and nuclear submarines is the power generation system. Nuclear submarines employ nuclear reactors for this task, they either generate electricity that powers electric motors connected to the propeller shaft or rely on the reactor heat to produce steam that drives steam turbines. Reactors used in submarines use enriched fuel to enable them to deliver a large amount of power from a smal
Project 955 or Borei alternate transliteration Borey is a class of nuclear-powered ballistic missile submarine produced by Russia and operated by the Russian Navy. The class is intended to replace the Delta III, Delta IV and Typhoon classes in Russian Navy service; the class is named after the North wind. Despite being a functional replacement for many types of submarines, the Borei-class submarines are much smaller than those of the Typhoon class in both volume and crew, are in terms of class more a follow-on to a replacement for the Delta IV-class SSBNs; the first design work started in the mid-1980s, the construction of the first unit of the Borei class started in 1996. A new submarine-launched ballistic missile was developed in parallel, called the R-39UTTH "Bark". However, the work on this missile was abandoned, a new missile called the Bulava was designed; the submarine needed to be redesigned to accommodate the new missile, the design name was changed to Project 955. The vessels are being built at the Northern Machinebuilding Enterprise in Severodvinsk, were designed by the Rubin Marine Equipment Design Bureau.
Because of the repeated failures during Bulava test launches, some experts suggested that the Borei submarine could instead be armed with R-29RMU Sineva missiles. The Sineva is in active duty on the Delta IV-class submarine. Advances include a compact and integrated hydrodynamically efficient hull for reduced broadband noise and the first use of pump-jet propulsion on a Russian nuclear submarine; the noise level is to be five times lower when compared to the third-generation nuclear-powered Akula-class submarines and two times lower than that of the U. S. Virginia-class submarines; the Borei submarines are 170 metres long, 13 metres in diameter, have a maximum submerged speed of at least 46 kilometres per hour. They are equipped with a floating rescue chamber designed to fit in the whole crew. Smaller than the Typhoon class, the Boreis were initially slated to carry 12 missiles but are able to carry four more due to the decrease in mass of the 36-ton Bulava SLBM over the proposed R-39UTTH Bark.
Cost is some ₽23 billion, in comparison the cost of an Ohio-class SSBN was around USD$2 billion per boat. A fifth generation successor/supplement is in development; the launch of the first submarine of the class, Yury Dolgorukiy, was scheduled for 2002 but was delayed because of budget constraints. The vessel was rolled out of its construction hall on 15 April 2007 in a ceremony attended by many senior military and industrial personnel. Yuriy Dolgorukiy was the first Russian strategic missile submarine to be launched in seventeen years since the end of the Soviet era. There are three more Borei-class submarines under construction, named Alexander Nevsky, Vladimir Monomakh and Knyaz Vladimir; the planned contingent of eight strategic submarines is expected to be commissioned within the next decade. Although Yuriy Dolgorukiy was rolled out of its construction hall on 15 April 2007 the submarine was not put into the water until February 2008. By July 2009 it had yet to be armed with Bulava missiles and was therefore not operational, although ready for sea trials on 24 October 2008.
On 21 November 2008 the reactor on Yuriy Dolgorukiy was activated and on 19 June 2009 began its sea trials in the White Sea. In August 2009 it was reported that the submarine would undergo up to six trials before being commissioned but the problem with the Bulava missile could delay it more. On 28 September 2010 Yuriy Dolgorukiy completed company sea trials. By late October the Russian Pacific Fleet was prepared to host Russia's new Borei-class strategic nuclear-powered submarines, it is expected that four subs will be deployed in the Northern fleet and four subs in the Pacific fleet. On 9 November 2010 Yuriy Dolgorukiy passed; the plan was to conduct the first torpedo launches during the ongoing state trials in December 2010 and in the same month conduct the first launch of the main weapon system, R-30 Bulava missile. The plan was postponed to mid-summer 2011 due to ice conditions in the White Sea. On 2 December 2010 the second Borei-class submarine, Alexander Nevskiy, was moved to a floating dock in Sevmash shipyard.
There the final preparations took place. The submarine was launched on 6 December 2010 and began sea trials on 24 October 2011. On 28 June 2011 a Bulava missile was launched for the first time from the Borei-class submarine Yuriy Dolgorukiy; the test was announced as a success. After long delays the lead vessel, Yuriy Dolgorukiy, joined the Russian Navy on 10 January 2013; the official ceremony raising the Russian Navy colors on the submarine was led by Russian Defense Minister Sergey Shoygu. It was deployed in 2014 after a series of exercises. On 17 November 2017, the fourth Borei-class submarine and the first of the improved Project 955A, the Knyaz Vladimir was moved out of the construction hall at the SEVMASH shipyard; the submarine was launched a year and subsequently started its factory trials. It has been reported that the a