The Sarov-class submarine is Russia's one-off B-90 / Project 20120 special-purpose submarine, a hybrid diesel-electric and nuclear test boat begun at Krasnoye Sormovo and completed by Sevmash under Rubin design authority. Open sources place it with the Northern Fleet as a secretive trials platform for reactor technology, unusual payload arrangements, and Poseidon-related undersea weapon work rather than as a standard attack submarine.
Open sources describe B-90 Sarov / Project 20120 as a Russian special-purpose submarine used for reactor, payload, and Poseidon-related undersea weapon testing. They do not connect the boat to a specific combat conflict, so this page keeps the holding conflict context narrow.
The boat's unusual value is its experimental layout: open sources connect Sarov to reactor trials, extended-submerged endurance concepts, and large undersea payload testing.
| Feature | Importance | Limit |
|---|---|---|
| Hybrid propulsion context | GlobalSecurity describes the submarine as combining diesel-electric machinery with a small nuclear reactor concept intended to extend submerged operations. | Public accounts differ on the exact auxiliary reactor or electrochemical-generator arrangement. |
| Bow payload bay | Covert Shores describes a prominent bow hangar area and no normal torpedo-tube arrangement, supporting the interpretation of a test-payload submarine. | The exact internal arrangement remains inferred from imagery and specialist analysis. |
| Poseidon association | RussianShips.info and Covert Shores both connect B-90 Sarov with 2M39 Poseidon / Kanyon test work. | This supports development and testing context, not operational combat use by Sarov. |
Sources: Project 20120 Sarov; Project 20120 Sarov Experimental Submarine; Sarov Class submarine demystified.
Sarov is better treated as a single experimental boat with several names and project labels, not as a class with multiple known variants.
| Label | Meaning | Note |
|---|---|---|
| B-90 Sarov | Boat name and hull identity | The completed submarine was accepted by the Russian Navy in August 2008 as the single completed Project 20120 boat. |
| Project 20120 Sargan | Project/design label | RussianShips.info lists Project 20120 as Sargan and identifies one completed unit, with work started at Krasnoye Sormovo and continued at Sevmash. |
| Sarov class | Western/NATO-style class label | The label describes the one-off submarine for catalog and reference use; it should not imply a multi-boat production class. |
Sources: Project 20120 Sarov; Project 20120 Sarov Experimental Submarine.
The unfinished Project 20120 hull was laid down at Krasnoye Sormovo before the program was halted in the post-Soviet funding collapse.
Sources: Project 20120 Sarov Experimental Submarine
Open-source accounts say Russian authorities decided in 2001 to continue the experimental submarine at Sevmash, followed by revised project work and resumed construction in Severodvinsk.
Sources: Project 20120 Sarov Experimental Submarine
RussianShips.info lists B-90 as becoming Sarov in May 2007, with the same entry describing the boat as a universal test platform tied to 2M39 Poseidon development.
Sources: Project 20120 Sarov
After work resumed at Sevmash, the submarine was launched and moved closer to completion under the new Sarov name.
Sources: Project 20120 Sarov, Sarov Class submarine demystified
The Russian Navy accepted the submarine into service, making B-90 Sarov the only completed Project 20120 boat.
Sources: Project 20120 Sarov, Sarov Class submarine demystified
Covert Shores identified Russian Ministry of Defense Poseidon test footage released in February 2019 as seemingly taken aboard Sarov, while noting visible differences and the limits of the identification.
Sources: Sarov Class submarine demystified
