South Korean Submarines, 3,000+ ton KSS-III, Nuclear Potential

See detail on possible South Korean nuclear submarine technology in redded KSS-N sub-heading below.

One of South Korea's (international convention of just "Korea" now used) nine Chang Bogo class (KSS-Is). Korea is completing a sale of three to Indonesia.

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One of Korea's four Son Won-Il class (KSS-IIs) in commision - five to go. Larger than the KSS-I and AIP equipped. Looks like a pre-launch ceremony. 

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With the KSS-III being described as a "3,000 tonne submarine" for a decade the above dimensions (very similar to the single hull Collins) may be accurate. The "3,000 t" would be surfaced displacement.

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A larger KSS-III? If its length is really 83.5 m and breadth/beam 7.7 m, then compared with the Collins (77.4 m, 7.8 m) the KSS-III's displacement appears to be around 3,400 tonnes (surfaced) and 3,800 tonnes (submerged). There are many other variables in estimating displacement of course! Other possibilities are that the above is a "4,000 t" nuclear KSS-N? or 83.5 is propaganda to equal the Soryu's 84 m length.

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Another model of what the KSS-III may turn out like. It appears to have 6 VLS hatches but a 6 missile Vertical Multi Purpose Lock (VMPL) is more likely.
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South Korea (international convention of just "Korea" now used) has a long and competitive ship-building tradition. Korea has the world's largest ship-building industry - with 41% of world market share (in first quarter 2015). This has put Korea in a good position to build German TKMS-HDW designed submarines (from kits?) since 1990. Korea has also has submarine export success and is perhaps well prepared to develop a 3,000-4,000 tonne conventional submarine. It faces threats even greater than Japan does - having a land border with North Korea and in much closer proximity to China. The Korean Navy has publicised its creation of a Submarine Command for reasons difficult to discern but perhaps to suggest an eventual capability of a pre-emptive or second strike nuclear deterrent.

South Korea's KSS-I, KSS-II and KSS-III building program suggest a goal of having a rolling average of at least 18 submarines operational and perhaps 22 to match Japan's medium term goal. The so-called "indigenous" submarine (KSS-III) project may still draw heavily on TKMS-HDW technology but "indigenous" also provides ambiguity if Korea needs to develop KSS-III into a nuclear propelled submarine "KSS-N" possibly nuclear armed. 

South Korea's strategy includes the creation of a pre-emptive strike "kill chain" (of threat detection, decision making-authorisation and (mainly missile) pre-emptive strike) against North Korea. Submarines would be a (or the) principal pre-emptive strike and counter-strike platform. Subsonic cruise missiles are generally too slow for these roles - making supersonic+ cruise and ballistic missiles the logical solution.

Used South Korean has two Dolgorae class mini submarines (above) launched 1990 and 1991, 175 tons, with two small 410mm torpedo tubes. They have crews of 14 and may be used for surveillance and perhaps special forces. They were acquired by South Korea to obtain initial experience with the basics of operating a submarine force and to train surface ASW ships in the detection of subs.

In 2011 South Korea indicated it would be building new mini-subs, known as KSS-500As, weighing 510 tons. They may operate only on Lithium-ion Batteries and diesel engines. 

KSS-Is and KSS-IIs

Korea's navy operates:

- 9 Chang Bogo class (KSS-I), a variant of the TKMS-HDW type 209/1200. In 2011 Daewoo Shipbuilding & Marine Engineering (DSME) won a contract to supply Indonesia with two pre-assembled Chang Bogos (to be delivered probably in 2016-2017) with a third Chang Bogo to be assembled in Indonesia (perhaps the beginning of an indigenous Indonesian production line!). The 9 KSS-Is have been regularly upgraded which may extend their service life past the usual 30 years. A major future upgrade may be Lithium-ion batteries fully or partly replacing lead-acid batteries - although such a retrofit may be very difficult. See NTI document for names of specific, commissioned KSS-Is and KSS-IIs up to 2011.

-  4 Son Won-Il class (KSS-II) as at April 2015. Five more are due to be commissioned by 2020. These are variants of the TKMS-HDW Type 214 submarines. Hyundai Heavy Industries (HHI) built the first three (commissioned 2007-2009). DSME, HHI and STX Offshore & Shipbuilding are alternately building the second batch of six with one of the six commissioned in December 2014 and the final one due to be commissioned in 2018. Like the KSS-Is the KSS-IIs carry some US built Harpoon missiles for anti-ship and possibly land attack. Like the KSS-Is the KSS-IIs are orientated to a surveillance, anti-shipping, anti-submarine and (a short range) land attack capability. 

KSS-III, 3,000-4,000 tonne Design - Conventional and Potentially Nuclear  

There will be eventually 9 (KSS-III) 3,000-4,000 tonne submarines.  See the 3rd and 4th pictues above that contain varying dimentions attributed to the KSS-III (also called "DSX-3000") which indicate its surfaced displacement may be anywhere between 3,000 and 3,400 tonnes. DSME will be the main designer. The lead KSS-III boat began development in November 2014 at DSME's submarine yard at Okpo. It my be a major step forward in utilising Lithium-ion Batteries (LIBs). The second batch of KSS-IIIs (especially if they use new technology LIBs) may take 8 years to build and launch (2024) and then 3 years to commission (about 2027). 

The larger size of the KSS-III will permit it to include some of the latest submarine technologies, including:

- large diameter unmanned underwater vehicles (LDUUVs)
- Seal/diver delivery vehicles (SDVs)
- dry-wet cells for special forces in dinghies/divers/Seals
- VLS or more probably the major advance of Vertical Multi Purpose Lock (VMPL) capable of launching 1,500+ km cruise and Harpoon missiles,, VMPLs are also capable of launching LDUUVs and SDVs. 

As well as retaining fuel cell (or less likely Stirling) AIP, KSS-IIIs could also incorporate features from the TKMS-HDW Dolphin 2 including the large rudder system and reinforced hull bottom which allow such a large SSK to operate in shallow, littoral waters. Also Germany's TKMS-HDW could provide assistance using features from the so-far drawing board only HDW 216 (intended to be a 3,000+ tonne design). 

One additional reason Korea is going the indigenously developed submarine route is that international political pressure on Germany would probably prevent Germany from openly assisting South Korea to develop the KSS-III in the medium-long term into a nuclear propelled KSS-N submarine, possibly armed with nuclear weapons.

The capability to use Tomahawk or indigenous Hyunmoo-3 series cruise missiles of 1,500+ km (far longer than the 140 km range KSS-I/KSS-IIs UGM-84 Harpoons) potentially makes the KSS-III much more effective against such additional threats as China and Russia. The future KSS-IIIs may also be capable of firing ballastic missiles.

The US may have been politically unwilling to supply the Tomahawk to Korea. Instead Korea appears to have incorporated many of Tomahawk's features into the Hyunmoo-3 series. By building an indigenous missile, warhead ambiguity is introduced. Korea is one of those countries (like Japan) that could develop a nuclear weapon in less than a year. Miniaturisation may be a major hurdle but a Hyunmoo-3 (or other cruise missiles) could trade range to achieve a heavier warhead than 500 kg.

KSS-III could best be described as multi-purpose. For a medium sized navy like Korea's KSS-IIIs (or KSS-Ns) could combine some of the capabilities that larger navies cover more comprehensively with distinctly different types, such as SSKs, SSNs, SSGNs and SSBNs. 

KSS-N, a Nuclear Development of the KSS-III? 

Korea appears to have long maintained an option of a KSS-N (also called KSSX-N and SSX) a 4,000+ ton nuclear propelled development of the KSS-III. On past plans see Globalsecurity.com report. However to date any plan has not occurred due to pressure from all of Korea's neighbours, US opposition and the necessity of building an indigenous submarine rather than a submarine that heavily relies on a foreign country (Germany). Also a nuclear propelled Korean submarine would diminish any chance that North Korea would remove/destroy its nuclear weapons and ballistic missiles. Korea might develop the KSS-N submarine if threats against it sufficiently increase and/or US military support diminishes.

Korea has long and extensive experience building nuclear power reactors - mostly large but still useful in any future development of submarine reactors. Interestingly DSME (as at April 2015) appears to be designing a "nuclear propulsion [surface] ship". This would have the legitimate purpose of meeting market demand for nuclear propelled, very large, ice-breaking, oil and LNG tankers. This activity also provides dual-use potential for submerged nuclear propulsion. 

In terms of an actual reactor technology path the Korea Atomic Energy Research Institute (KAERI) is also operating and further developing a small 100 MW ("SMART") pressurised water reactor with a output (at least) that may suite a 4,000 ton KSS-N. The SMART reactor's main current weakness is that it uses 5% enriched Uranium (U) 235 providing a poor power to size/weight ratio. 5% means SMART presently needs three year (overly frequent) refueling. Korea probably could legitimately develop the SMART at a higher (ice breaker surface ship) U enrichment percentage to make it much more useful as a submarine reactor. Korea has been seeking IAEA-US permission to develop a greater U enrichment capability but has been blocked. Although at a small amount-laboratory level Korea has a proven Uranium enrichment ability.

So Korea's indigenous submarine (KSS-III) program is well worth watching for its potential.

I'll do an article on North Korea's submarine situation in the future.

More Sources

http://www.nti.org/analysis/articles/south-korea-submarine-capabilities/

http://www.defensenews.com/story/defense/show-daily/sea-air-space/2015/04/12/korea-south-north-navy-modernize-coastal-scandal-sub-helicopter-frigate/25512681/

http://www.globalsecurity.org/military/world/rok/kss-n.htm

Pete