Tolgorae-class submarine
| File:Tolgorae-class.png Tolgorae-class
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| Class overview | |
|---|---|
| Builders: | KSME |
| Operators: |
list error: <br /> list (help) Anikatian People's Navy Anikatian Navy |
| Preceded by: | Tarango III-class |
| Succeeded by: | Korae-class |
| Built: | 1968–1975 |
| In service: | 1969-Present |
| Planned: | 16 |
| Completed: | 6 |
| Cancelled: | 10 |
| Active: | 0 |
| Laid up: | 2 |
| Lost: | 1 |
| Retired: | 3 |
| General characteristics | |
| Type: | Submarine |
| Displacement: |
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| Length: | 109 m |
| Beam: | 11.6 m |
| Draft: | 8 m |
| Propulsion: |
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| Speed: |
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| Range: | Unlimited, except by food supplies |
| Endurance: | 70 days endurance |
| Test depth: | 320-400 m (1,049-1,312 ft) |
| Complement: | 80 crew (32 officers, 34 warrant officers, 15 enlisted) |
| Armament: |
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The Tolgorae-class submarine was the first pupose built Anikatian class of nuclear-powered cruise missiles submarines that were built by the DSRA. The official designation by the Anikatian People's Navy was the Tolgorae-class, but the manufacturer designation of this class was Project 471; Tolgorae (돌고래) means dolphin in the Anikatian language.
History and development
Even before the first Tarango-class submarines had to be completed work on an all new larger nuclear-powered vessel as research and develop along with assistance from Estovnia sped up the nuclear program. The new class of submarine was to have a displacement of greater than 4,000 tonnes and diving depth of at least 300 m. Skills and knowledge learnt from the Tarango program fed into the new nuclear submarine development and designs were set for a shift to a single highly efficiency propeller setup over the older three shaft design to help reduce noise and improve hull streamlining. Further development was achieved in the shaping of the hull with a far more teardrop shaped hull as a result of improved metal production and welding techniques. The overall design was far larger to accommodate a newly developed steam turbine nuclear propulsion system. This would be the Songŏryu-class but design work was would feed into work on a new generation of high-speed submarine with an advanced nuclear power plant and with the possibility of launching cruise missiles from a submerged position was recommended using experience from the Tarango-class submarines. Because of differing requirements the hull shape was different and the Tolgorae-class would fit a two shaft design to increase high-speed performance. The hull was completely different to fit nuclear cruise missiles although many subcomponents and propulsion subsystems were shared.
One experimental vessels was built with a liquid sodium, epithermal, superheated, reactor and steam power plant. Which was more powerful than standard light water reactor used in most Anikatian vessels. The saturated steam plant, reduced the size of the machinery in the engineering spaces nearly 40%. The liquid-sodium cooled epithermal reactor was more thermally efficient than a light-water-cooled system, quieter, which greatly interested the DSRA but posed several possible safety hazards for the ship and crew. These concerns were proved as the vessel suffered welding cracks in the superheaters tube sheet which allowed high-pressure steam to leak into the low-pressure primary system and react with the sodium to form sodium hydroxide and H2. While conducting a trial patrol, this problem continued and then the reactor suffered a major coolant leak which caused a serious accident.
Intense vibration caused a thermowell inside a pipe carrying sodium coolant to break, possibly at a defective weld point, allowing several hundred kilograms of sodium to leak out onto the floor below the pipe. Upon contact with air, the liquid sodium reacted with oxygen and moisture in the air, filling the engine room and hill with caustic fumes and producing temperatures of several hundred degrees Celsius. The heat was so intense that it warped several steel structures in the room.
Fifteen sailors were killed outright in the initial leak, and two more died soon afterward from toxic gas poisoning. An alarm sounded switching the system over to manual operations, but a full operational shutdown was not ordered until after the fumes were detected. The vessel then surfaced on emergency battery power alone and then the Captain requested to have the ship towed by an Anikatian freighter back to her home port. Although a towline was attached, the towing attempts were unsuccessful, and after another critical explosion as one of the sodium leaks came into contact with the water the vessel sank.
Variants
- Tolgorae I (Project 471): The baseline configuration, these were nuclear-powered submarines that first saw service in 1969; 4 were built. They had 6 torpedo tubes and carried 16 torpedoes, mines.
- Tolgorae II (Project 471A): An experimental vessel converted from a Tolgorae I, these were built with a experimental sodium liquid metal cooled nuclear reactor and it first service in 1971; 1 was built. They had 6 torpedo tubes and carried 16 torpedoes, mines.
Units
Following is a list of all 6 Tolgorae-class submarines built for the DSRA.
| Number | Shipyard | Project | Laid down | Launched | Decommissioned | Status |
|---|---|---|---|---|---|---|
 S-162 |
Kyoungcho Shipbuilding & Marine Engineering Eunchuol Shipyard | 471 | 1968 | 1969 | 2001 | Decommissioned for scrapping |
| S-163 |
Kyoungcho Shipbuilding & Marine Engineering Eunchuol Shipyard | 471 | 1969 | 1970 | 2001 | Decommissioned for scrapping |
| S-164 |
Kyoungcho Shipbuilding & Marine Engineering Namsong Shipyard | 471A | 1969 | 1971 | 1987 | Rebuilt with experimential sodium liquid metal cooled nuclear reactor. Sunk by explosion caused by sodium leak in the reactor system. |
| S-165 |
Kyoungcho Shipbuilding & Marine Engineering Eunchuol Shipyard | 471 | 1970 | 1973 | 2001 | Decommissioned for scrapping |
| S-166 |
Kyoungcho Shipbuilding & Marine Engineering Namsong Shipyard | 471 | 1971 | 1974 | 2001 | Decommissioned for scrapping |
| S-167 |
Kyoungcho Shipbuilding & Marine Engineering Eunchuol Shipyard | 471 | 1973 | 1975 | 2001 | Decommissioned for scrapping |
Operators
Most saw service in the Anikatian People's Navy.
- Anikatian Navy All retired and or scrapped.
- Anikatian People's Navy (passed on to successor states)