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

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.

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. 

KSS-Is and KSS-IIs

Korea's navy operates:

- 9 Chang Bogo class (KSS-1), 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. A major future upgrade may be Lithium-ion batteries fully or partly replacing lead-acid batteries - better to incorporate such batteries-electricals into the remaining new-build KSS-IIs rather than attempt a retrofitting.

- several mini-submarines exist but are probably too old, making them non-operational.

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.  If their length is 83.5 m and breadth/beam 7.7 m (see photo above) then they may displace 3,400 tonnes (surfaced) and 3,800 tonnes (submerged). DSME will be the main designer. The lead KSS-III boat began development in November 2014 at DSME's submarine yard at Okpo. The first KSS-III may take 4 years to build and launch (2018) then commissioning in about 2022. 

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

- Lithium-ion batteries, best for new build subs rather than retrofitted.
- 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.  

One additional reason Korea is going the indigenously developed submarine route is that Germany's  TKMS-HDW would be banned by German (and probably international) law from 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 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.

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Pete