Sarov

   The Project 20120 Sargan is the Russia's top-secret special purpose submarine. Only one submarine of this project, the Sarov, was built to date. It is named after a closed city, which played an important role in the Soviet nuclear weapons program. First details about this submarine were accidentally revealed in 2007. Development of this vessel commenced in 1988. Construction was started in Nizhniy Novgorod, however it was stopped in 1998 due to funding problems. In 2003 construction continued in Severodvinsk, after revision of the project. According to Russian news services, this submarine is a technology demonstrator, designed for testing of new technologies and weaponry. Other sources claim, that it is an intelligence collection boat. The Sarov was commissioned in 2008.

   It seems that this submarine uses a modified hull of the Kilo class. This vessel has a crew of 52. It is reportedly operating in northern waters. It is worth mentioning that during the Cold War, Soviets operated several spy submarines in the North.

   The Sarov is a diesel-electric submarine, however it has a small nuclear reactor as a supplementary power generator. It is a unique combination. 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. Such air independent propulsion system is a significant Russian development and might be used in the next generation patrol submarines.

   Some sources suggest that the Sarov might have two 650-mm torpedo tubes.