Project 20120 Sarov Experimental Submarine
(Auxiliary submarine (SSA(N))

The first ship of Project 20120 is the B-90 Sarov. It has been identified as a test platform for new reactor technologies and also a spy submarine. Sarov is named for the closed town in Nizhny Novgorod Oblast, Russia that is the center for Russian nuclear weaponry. The Project 20120 submarine contains propulsion technology radically different from any other submarine in service. On the sides of the hull in front of the sail are "floating blocks" - podes that may contain additional compensating ballast system tests of the prototypes and torpedoes, or possibly accoustic sensors or autonomous underwater vehicles.

Development of this vessel commenced in 1988 as an Opytovaya Bolshaya Dizel'naya Elektricheskia Podvodnaya Lodka [Test Large Diesel-Electric Submarine. A decision on the boat "Garfish" started in 1988 the CDB MT Rubin, Chief Designer ALEXANDER Belov (completed in March, 1988). In March 1989, approved by the technical design and development of working drawings. There is an assumption that the design was inspired by the project PL 877B, a Single experimental Kilo boat with pumpjet in place of propeller.

There are few details about the boat's auxiliary nuclear reactor, reportedly designated VAU-6, evidently designed to allow the diesel boat to remain submerged for greater periods of time. The VAU-6, designed by NIKIET in the late 1960s, was a boiling water reactor according to the NIKIET website (some other sources state that it is a pressurized water reactor).

In the mid-1960s at the NIKIET an unusual NPS draft single-circuit-6 boiling reactor was an original sealed [hermetic] type with water lubricated bearings. For installing, operating and placed in a capsule, outside the main hull of the submarine. This ensured the radiation safety of the crew, both during normal operation, and in case of emergency or war damage. The Reactor VAU-6 c-WOW for diesel-electric submarine were produced pilot production NIKIÈT. A one-loop prototype 600 kW VAU-6 was constructed in 1971, and a second reactor in 1986. The latter was reportedly fitted on a Project 651E [NATO Name: 'Juliett'].

The submarine [PL Podvodnaya Lodka] project "Garfish" (factory No. 137) was laid down at Krasnoye Sormovo Shipyard (Nizhniy Novgorod) 18 September 1988 and unfinished road (completition NAVY plan-1993). Construction halted in 1998 when it was 40% complete due to funding problems.

A decision on the construction at the "Sevmash" was made in October 2001. In 2003 construction continued in Severodvinsk, after revision of the project. The "Garfish" design came to completion on a finalized design in June 2003 under Chief Designer A. Praselin. Project 20120 began work at "Sevmash" in Severodvinsk in August 2003.

The reinstallation of mortgage boards [Fitting boards] came on 19 March 2006. The mortgage boards are silver, chrome-plated steel or brass plate with text, usually containing the name of the ship, the date of its foundation, and other information, which is traditionally placed in a metal pocket on the mortgage section (installed on the stocks first) during the solemn ceremony of laying the ship. The tradition comes from ancient times. It was customary to place in the hull or mast of a coin or other mascots who were believed to have helped Mariners propitiate the supernatural seas.

On 26 May 2007 by order No. 025 the Commander Navy named the boat "Sarov". On 14 December 2007, the submarine sssembly shop of "Sevmash" and 24 December 2007 lowered into the water at Severodvinsk. Fitting started 01 January 2008, and in July 2008 the boat passed factory sliding and State testing. It was accepted by the Navy on August 7, 2008, and based in the northern fleet (2009 at Severodvinsk).

As of 2009 the Russian Navy had at least seven "special purpose" submarines designed for testing of new technologies and weaponry.

In February 2007 an issue of Nizhegorodoskaya delovaya gazeta (Nizhny Novgorod Business Newspaper) was dedicated to the anniversary of the Afrikantov Experimental Heavy Equipment Design Bureau, the leading developer of nuclear reactors for submarines. One article reported that in 2006 the bureau "developed a project for the new atomic submarine Kalitka, on which a principally new steam generating system, the Phoenix KTP-7I, is being installed."

Municipal authorities in Sarov, Nizhny Novgorod Region, accidentally revealed the design for the latest Russian submarine when it posted an account of a meeting with its commander on its website. The high level of secrecy surrounding the submarine suggested that it is a unique experiment on the part of scientists and the military. On 06 September 2007, the official site of the city of Sarov reported on a visit to the city by the commander of the submarine Sarov Capt. 1st Rank Sergey Kroshkin. It stated that the Sarov was still in the stocks at the Severodvinsk but "the chief commander of the Navy has set the task of finishing work by the end of the year." The number of the submarine project was given: 20120 and its technical and tactical characteristics as well. Those data indicate that the new submarine is very similar to the Project 877 Paltus (Halibut) diesel submarine, but its water displacement is greater (3950 vs. 3050 tons).

On 11 September 2007, that information disappeared from the site, but it had already been reprinted by the local media. Russian Navy representative Alexander Smirnov told Kommersant, that he "knows nothing" about the Project 20120. A Zvezdochka shipbuilding enterprise spokesman stated that no new submarines are being built there. Northern Machine Building Enterprise (Sevmash) in Severodvinsk declined to answer questions. There were no diesel submarine hulls at Sevmash. That plant has specialized in atomic submarines for the last 45 years, except for two Project 636M diesel submarines delivered to the Chinese Navy in 2005. The Rubin central design bureau, a leading developer of submarines, also declined to confirm or deny its involvement with the Project 20120. The Krasnoe Sormovo plant, which made the first, Soviet diesel-atomic submarine, said it had no information about the Project 20120.

The Krasnoe Sormovo plant technical director Alexander Tsepilov stated that the unfinished hull of the experimental submarine Sargan, begun in the late 1980s, was sent to Northern Machine Building Enterprise in 2006. It is possible that the Project 20120 was made from the base of the Sargan. The completion of the Sargan was confirmed in the annual report of Krasnoe Sormovo for 2005, in which, among other work, the "production of a masted lifting apparatus for the Sargan order" for delivery in 2006 was mentioned.

The secrecy of the new project caused surprise. In recent years, everything connected with shipbuilding has been widely covered by the media. Not only have the launches of new ship turned into big events, such purely technical operations as the transfer of the submarine Yury Dolgoruky from the workshop to the dock have as well. Officials freely divulge project numbers, names and other details to journalists.

Several countries are working on modernizing diesel submarines to create an inexpensive submarine with the autonomy of an expensive atomic model. Germany has had the most success so far, building Project 212A subs with anaerobic engines (that do not require atmospheric air) since 2000. Those submarines can remain underwater for 20 days without surfacing. Typically diesel submarines cannot remain underwater longer than four or five days.

One theory was advanced that experimental Project 20120 is to test unique technology - possibly the installation of an atomic reactor on a diesel submarine as a backup energy source. Similar experiments were conducted in the USSR. In 1985, a B-68 diesel submarine was equipped with a supplemental VAU-6 atomic reactor with a capacity of 600 kW, which gave it the ability to spend longer periods under water. It is possible that Russian scientists decided to renew the program to install a mini-reactor in a diesel sub in response.

A second theory is that the submarine would test a new nuclear reactor. That possibility was first mentioned in February of this year in an issue of Nizhegorodoskaya delovaya gazeta (Nizhny Novgorod Business Newspaper) dedicated to the anniversary of the Afrikantov Experimental Heavy Equipment Design Bureau, the leading developer of nuclear reactors for submarines. It says in an article that the bureau last year "developed a project for the new atomic submarine Kalitka, on which a principally new steam generating system, the Phoenix KTP-7I, is being installed." It is possible that the mysterious Project 20120 is connected with the equally mysterious Kalitka project.

Russia's Sevmash shipyard at the Arctic city of Severodvinsk completed a hybrid submarine powered by a diesel-electric plant and a small nuclear reactor. Designated B-90 and named Sarov, the submarine was completed on 17 December 2007. The B-90 was designed by the Rubin design bureau in St. Petersburg. Construction was begun at the Krasnoe Sormovo shipyard in Nizhnii Novgorod (formerly Gor'kiy), and the submarine was then transported through the inland waterways to the Sevmash yard for completion.

One of the first misinformations on the internet is her size. Because she was based on a KILO Class submarine hull her length is generally quoted as 72m (236ft) long and 9.9m (32ft) wide. In fact she is nearer to 98m (322ft) long. This is immediately apparent from satellite imagery and from photographs of her tied up alongside a KILO Class boat. The extra length fits with the addition of the nuclear reactor section immediately aft of the sail. The sail itself is also much larger than on the KILO and now contains an escape capsule section like on recent Russian nuclear submarines.

The other curiosity is the forward section, which has a pronounced overbite just below the waterline. The receding chin seems to follow the same profile as the KILO class, with the upper section being an extension. There is no provision for torpedo tubes but the protruding nose features a large square cut hanger door where the torpedo tubes would ordinarily be. Below and this on the starboard side of the bow is a small square-cut hatch with an externally opened handle suggesting a diver access. More noticeable, behind this along the waterline are large sponsons which may contain either lateral sonar arrays or some form of ballast tanks for the hanger section. It would be easy to speculate of course, but it does all add up to a very unique boat.

The submarine is said by some to operate in northern waters as a spy-vessel belonging to Russia's Northern fleet. The nuclear reactor is designed to charge the batteries, so the submarine can stay much longer underwater. Unlike normal diesel-electric submarines the Sarov can stay submerged for up to 20 days, totally silent. It is the most important feature for intelligence collection submarine, not to be detected by seabed systems, foreign warships and submarines.

The only thing is known that Sarov is powered with Kristall-27 powerplant with electrochemical generator. The Russian navy describes the Kristall-27 AIP system as an "electrochemical generator". No other details are forthcoming about Kristall-27, and it's unclear if this system is carried along with the microreactor, or if it has since replaced it. According to the rusnavy.com website, Sarov has a maximum endurance of 90 days. Other sources have given an endurance of 45 days; it is possible that the latter figure refers to submerged endurance (unlike a true SSN, an AIP or micro reactor submarine must still occasionally surface).

As of 2019, in addition to the "Belgorod" under the veil of secrecy will have to work another submarine, this time diesel-electric. B-90 "Sarov" is the only representative of the project 20120 and is also intended for testing new systems. There is very little information about this boat. Sometimes it comes to rumors and legends. For example, it is often mentioned that Sarov has an all-titanium housing and can even be equipped, if necessary, with a special small-sized nuclear reactor that can replace an existing diesel-electric power plant.