April 16, 2015

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

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.
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. 
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.

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.
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.

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. 

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. 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.

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 tonnesDSME 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) - perhaps Hanwha Lithium Iron Phosphate (LFP) batteries. The first KSS-III (especially if it uses 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:

- 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. 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) 4,000+ ton nuclear propelled development of the KSS-III. On past plans see Globalsecurity.com reportHowever 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



Anonymous said...

Dear Pete,

the South Korean KSS-III is according to size just a "short" Type 216. I think DSME and TKMS will still work together.

A nuclear submarine won't make any sense for South Korea. According to range and endurance even KSS-II / Type 214 is sufficient. South Korea doesn't need to track SSBNs because China is very close. Therefore high enduring speed is unnecessary.

According to German law it is legal to develop a nuclear propelled vehicle. There would be no legal obstacle for TKMS to help South Korea to develop a KSS-IVN. Just proliferation of nuclear weapons is banned by international treaties.

My guess is a Type 216 with a huge South Korean content.

Only ROKS Chang Bogo was built at HDW, Kiel. All following submarines were and are built in South Korea. The South Korean workers and engineers were trained in Kiel on the first submarine and then supported back in South Korea.

Quite the same for Turkey. The first three submarines were built in Germany and the following 11 submarines were built in Turkey just like the Type 214 replacing the most ancient Type 209s (1975+). TKMS will just deliver sets for the propulsion system and other systems Turkey wants. The rest will be done by Turkey.

Isn't South Korea also a friendly nation to Australia or the US just like Japan?


C.c.: Type 210mod would better suit Australia's needs and capacity.

Biswajit Pattanaik said...

Hi Pete,
Once again a nice aritcle.Your analysis is to the point,hats off to u.Indeed RoK have a very efficient shipbulding industry & accompanied ecosystem with them.
1)So what do you think of RoK's KSS-II Subs as an overall platform?
2)Does Australia (Govt. Agencies+Military) treat RoK as an ally or as a perceived threat?
3)IF (& that's a big"IF" ) in the future RoK decides that the KSS-III would indeed be an SSN,then what type of implications can it have on RAN;if any?
4)What could be RAN's strategy to counter all the upcoming SSNs,SSGNs,SSBNs & Aircraft Carriers(Nuclear+Conventional) in the Asia-Pacific & plus close to the Australian Waters as well?
Thanks In Advance.

Anonymous said...

Reality is the South Koreans wants to become a major global weapons seller, see K2 main battle tank, T50 or the THAAD like SAM system ROK is working on. US DOD has run into quite a few IP issues with ROK.
I wonder if ROK has thought thru how are they going to dispose of an SSN when its reactor expires? Dump them into the artic sea like the Russians did? Even Uncle Sam had to spend billions to transfer disposal technologies to Russia. The US only has 1 such facility.

Peter Coates said...

Hi MHalblaub

Yes it would make sense for South Korea (SK) DSME to continue to draw on TKMS design information (for a "short" Type 216).

Yes high SK content in a KSS-III is likely. This would especially be for missile launch and combat system for indigenous cruise or future SLBMs.

Given SK's strategic opposition includes Russian and Chinese SSNs this may be one reason for SK to at least have contingency plans for a KSS-N. Also if Japan built nuclear subs.

A KSS-N would also be a fitting platform if SK wants a nuclear second strike deterrent particularly agains North Korea.

Yes I accept German law would not ban German assistance to SK for a KSS-N. It would mainly be political opposition (from Russia, China, NK, Japan and the US) against such German help. Russia also would oppose Germany developing nuclear propulsion given Russia's traditional fear that the Germany military may become too powerful.

Interesting Germany allowed SK to bid and win the contract for 3 Chang Bogos/209s to Indonesia. Was it because Germany had stopped its own 209 assembly line?

Yes Australia has close strategic bilateral relations with SK and Japan. These relations also have a multilateral nature, being coordinated by the US as a regional alliance.


cc. a short 216 maybe, with LIBs, no AIP :)

Peter Coates said...

Thanks Biswajit Pattanaik

1) RoK's (I will call it SK's) KSS-II is a TKMS-HDW 214. It looks like a well balanced submarine with good range. I think it would serve Australia needs if the AIP were removed and Lithium-ion batteries (LIBs) used. Australia's Navy, if buying from TKMS, almost definitely wants a larger 216.

2) Australia considers SK an ally - this is mainly in the US regulated alliance structure. All 3 countries see China and Russia as potential strategic opponents.

3) If SK built a KSS-N then Japan would almost definitely respond by building a nuclear propelled "Soryu". (Japan and SK are not enemies but they are not friends either.) Australia would probably respond by asking the US to sell (about 6) Virginia SSNs/SSGNs to Australia.

4) Australia's current strategy is to support the US in order to persuade the US to keep on defending Australia against nuclear powers. This is called extended nuclear deterrence.

If the US didn't help or wouldn't at least sell us SSNs/SSGNs then Australia might need to develop its own nuclear weapons for "armed neutrality".



Peter Coates said...

Hi Anonymous

I agree South Korea (SK) would want to sell more weapons (like Sweden) if US IP/export/political controls allowed it. SK certainly is efficient.

Another reason is if Japan started selling arms, especially in the region, then SK would like to economically and politically counter it by also selling to the region.

If SK needed to build nuclear subs then I think disposing of them in 30 to 40 years time would not be a current concern. In any case with SK's nuclear and shipping sectors it is one of the most equipped countries to dispose of nuclear subs.

Complicating factors on nuclear disposal may well include SK public opinion and Japanese public opinion.



Anonymous said...

Hi Peter,
why would you want the AIP removed from TKMS Type 214 for Australia?

Peter Coates said...

Hi Anonymous (of April 21, 5:56 PM)

On AIP - "Why would you want the AIP removed from TKMS Type 214 for Australia?"

Several reasons:
- practical/modern AIP technologies have only been a 2 to 3 week submerged-slow or zero speed solution for around 2 decades. Ultimate, mauch better, AIP is nuclear for those nations that can afford it.

- fuel cell AIP is a bundled inclusion for buying 214s that several countries don't need.

- AIP is ideal for only a restricted range of mission profiles particularly moving slowly, short-range and sitting on the bottom. This is particularly in the Baltic Sea (or for Singapore - right next to the Malacca Straight) for 2 or 3 weeks.

- AIP has such downsides as being:
- very $ expensive
- non-replenisable during a mission
- very unsafe, flammable even
- weight expensive, displacing fuel-
oil or other features
- can break down (especially if it has
moving parts like the Stirling AIP)
- may be more efficient in cold water
rather than Australia's mainly warm
operating areas

For all these were reasons AIP was never placed in the Collins sub - even though the Swedish-Kockums designers specialised in AIP subs.

Australia's mission profile is very long distances, warm water, fast transit, then perhaps mainly medium speed patrolling. This places more value on (privileges) efficient conventional diesel-electic operation which would not be at the expense of weighty AIP inclusion.

Also technological advances are trending toward the ever-present diesel-electric that uses Lithium-ion batteries (LIBs) covering more of any AIP advantages.

The newest batch of Soryus are believed not to have included Stirling AIP but instead have LIB to cover slow, 2 week+? submerged operation. It is also possible Japan has developed its own AIP-like technologies specifically for working with LIBs.

A small AIP-like unit for emergency (sneak away) operation might be a future possibility for subs.



Anonymous said...

Hi Pete

I agree about weak points of hydrogen fuel cell system for submarine. Submarines of this type are safe under the ordinary or non battle situation, but most important thing is safety under the battle situation with strong vibration or shock. Even if hull is not damaged, if slight hydrogen leakage is caused by tiny damages of piping system including valves, pressure gauges and joints, the submarine becomes perfectly dysfunctional. Because concentration of explosion limit for hydrogen is very low, you must avoid any kinds of stimuli as such heat or electrical ignition which cause explosion. And in the case of accident with hydrogen leakage, perhaps you can not rescue the submariners by hull cutting with ignition.


Peter Coates said...

Hi Anonymous (April 21, 5:56 PM) and also "S"

Thanks for raising AIP issues.

I'm just writing an AIP article so I'll include those issues in it.



Anonymous said...

Hi Pete

I estimated underwater performances of 28SS (diesel+LIBs Soryu) compared with 16SS (current, diesel+AIP Soryu) based on the various assumptions. I can not guarantee the estimation. And I am sorry that I can not reveal information sources.

1) Conclusion: 28SS’s submerged speed, duration and range may be 7.5 knot/h, 30days and 5400nm, respectively.

2) Data and assumption
2a) LIBs performace
More than ten years ago, JMSDF (Japan Maritime Self-Defense Force) proved the LIBs showed 2 twice and 1.5 times bigger capacity and power than lead acid batteries, repectively.

2b) AIP space and batteries
16SS equips 50modules (500batteries), and 28SS can equip additional 200 modules in AIP space (=total 5times), I think.

3) Calculation and assumption
3a) Submerged speed
I assumed that submerged speed for 16SS is 6 knot/h and that submerged speed is proportional to square root of power.
Submerged speed for 28SS = 6knot/h x 1.25(square root of 1.5) = 7.5knot/h

3b) Submerged duration and range
I assumed that submerged duration for 16SS is 3days.
Submerge duration for 28SS = 3days x 2 (capacity ratio of 28SS/16SS) x 5 ( batteries ratio of 28SS/16SS) = 30days

Submerged range for 28SS = 30days x 7.5knot/h x 24h = 5400nm

Wether this calculation or asumption is right or not, 28SS will show excellent underwater performances. Although I oppose Soryu sub selling, I admit that option J-28SS is one of the best choices for Australia.


Peter Coates said...

Hi S (April 22 at 10:30 PM comment)

I have to admit that my level of knowledge, on AIP and battery capacity, is such that I've never heard of "SS" :)

I'll transfer your comments to my new AIP article (about to be published).



Anonymous said...

I think most Japanese know nuclear submarine is useless around east chinese sea.
it is not deep in the sea. it is easy to find the nuclear submarine.
more stealth is important. that is why south korea is an armature
submarine is a Coffin if it is found.

Peter Coates said...

Hi Anonymous just above - on East China Sea depths you are mainly right but there are major deep places. See http://www.britannica.com/place/East-China-Sea

"The East China Sea has an area of about 290,000 square miles (750,000 square km) and is largely shallow; almost three-fourths of the sea is less than 650 feet (200 metres), and its average depth is only 1,145 feet (350 metres). Extending alongside the Ryukyu Islands is the deeper part, the Okinawa Trough, with a large section more than 3,300 feet (1,000 metres) deep and a maximum depth of 8,912 feet (2,716 metres)."



Peter Coates said...

See "South Korea eyes French design for indigenous nuclear sub, sources say"

in DefenseNews, March 28-29, 2018: https://www.defensenews.com/industry/techwatch/2018/03/28/south-korea-eyes-french-design-for-indigenous-nuclear-sub-sources-say/

That DefenseNews article makes the important point that France's Barracuda (Suffren-class) SSN is an attractive design, to South Korea, from a nuclear proliferation viewpoint. In part because the Barracudas' K15+ reactor uses Low Enriched Uranium (LEU) (ie. less than 20% Uranium-235).

South Korea makes the assumption the US is less likely to block South Korean naval reactor plans if the reactor only uses LEU.