South Korean Nuclear Powered Subs by the 2030s: Predicted 2015-2021

Pete's earliest detailed comments on South Korea and its SSN ambitions were April 16, 2015's "South Korean Submarines, 3,000+ ton KSS-III, Nuclear Potential" at https://gentleseas.blogspot.com/2015/04/south-korean-submarines-3000-ton-kss.html in 2015 15 comments, 10,155 Page Views.

Pete wrote "S Korean nuke sub Reactor likely to be French K15 Variant" on December 16 2021 at https://gentleseas.blogspot.com/2021/12/s-korean-built-nuke-sub-reactor-likely.html 4 comments, 2,220 Page Views.
Please see text below: 

"India's Bharat Express News December 14, 2021 carries the New York Times (NYT) December 13, 2021 article "South Korea has long wanted nuclear submarines. A new reactor could open a door." without readers having to subscribe to NYT. NYT's article is reproduced by Bharat Express here https://www.thebharatexpressnews.com/south-korea-has-long-wanted-nuclear-submarines-a-new-reactor-could-open-a-door/

SUBMARINE MATTERS BACKGROUND AND COMMENT [written in 2021]

South Korea is leaning toward a [Low Enriched Uranium (LEU)] reactor solution perhaps initially on a South Korea SSBN - which will be based around the ballistic missile submarine KSS-III SSB. It is not surprising South Korea has long been in talks with France (since 2017 if not earlier) about South Korea building a variant of France's K15 LEU reactor. The K15 is on France's Triomphant class SSBNs and, in slightly smaller form, on the France's Barracuda-Suffren class SSNs. 

In Submarine Matters’ “South Korea seeks Submarine Reactors from US and RUSSIA” of October 22, 2019 South Korea may have concluded it is better to buy an existing submarine reactor or at least a ship reactor than totally reinvent a submarine reactor. 

Since 2017 (if not earlier) South Korea has been considering France’s new Barracuda SSN with its K15 (aka K 15 aka K-15) reactor. With North Korea's buildup of nuclear weapon and missile capabilities South Korea, in October 2019, has been testing any increased US willingness for South Korea to explore nuclear propulsion options. 

The Triomphant-class's 2(?) x K15s and Barracuda's single K15 reactor stands for 150 MWt  power which translates to a total of 30 MWe electrical power (for the French Barracuda’s non-propulsive electrical services hotel load + propulsion).

"In October 2017, the [South Korean] Navy commissioned the Seoul-based Korea Defense Network to conduct a five month study on the feasibility of developing an indigenous nuclear-powered attack submarine. The think tank reported in March 2018 the results to the Navy, suggesting the service build a nuclear attack submarine along the lines of the French 5,300-ton Barracuda-class sub. The French sub is fuelled by low-enriched uranium."

Now that the US and UK have given the green light to supplying Australia with a reactor under the AUKUS deal it is conceivable that France may want [to] supply just the Barracuda’s K15 reactor or transfer technology (including a reactor design) for South Korea to incorporate in its 4,000+ tonne KSS III Batch III building program. 

The Barracuda’s K15 reactor has the:

-  political/regulatory advantage of using LEU ie. less than 20% U-235 which South Korea sees as not being restricted by the NPT or nuclear Safeguards Agreements. This is compared to the political sensitivities and anti-proliferation regulatory restrictions (up until September 2021's AUKUS deal) placed on exporting/importing US and UK HEU submarine reactors. The UK/US reactors use weapons’ grade HEU of 93-97 percent (see p. 20). 

-  technical advantage of being built for a submarine of just over 5,000 tons, ie. in South Korea's KSS III Bach III weight bracket. While the KSS III Batch II with 10 x VLS silos  has diesel-electric (also AIP) propulsion the proposed KSS III Batch III may eventuall have 12 to 16 VLS silos requiring an unusually large propulsion solution. Nuclear has been the solution for SSBNs built by the US, Russia, UK, France, China and India. 

-  Also Naval Group's assistance to Brazil to create a SSN, known as Alvaro Alberto [~5,900 tonnes submerged?], is highly relevant to the South Korean SSN (aka KSS-N) project, Alvaro Alberto's projected launch year (2029) and commissioning (2032-2034) may occur in the same timeframe as the South Korean SSN project.  At Submarine Matter’s 2015 article see the subheading "Brazilian Nuclear Submarine (SN-BR)” “There currently appears to be expectations that SN-BR will be around 100m long and 9m wide. This coincides with France's Barracuda SSN dimensions of: 99.5m long and beam: 8.8m.” 

-  So a A K15 variant first mounted on a South Korean SSBN by the early 2030s may be followed by mounting a K15 reactor variant on a South Korean SSN by the mid 2030s. In terms of vertically launched cruise or ballistic missiles the KSS Batch I features 6 VLS tubes, each with one missile. The KSS III Batch II [now features 10] and the KSS III Batch III perhaps 12 to 16. 

South Korea's neighbour Japan (a part strategic competitor of South Korea) is observing South Korea's interest in nuclear propulsion and ever larger submarines.

India, already having SSBNs, is interested in building 6 x Project 75 Alpha class SSNs with specialised SSN reactors. India is naturally talking to France's Naval Group. Naval Group is already  helping India build the 6 Kalvari-class Scorpenes, and bidding for India's 6 x AIP diesel-electric Project-75I SSK competition. Naval Group produces all of France's SSNs and SSBNs. So India can have far ranging discussions, on many topics, with Naval Group."

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Very recently, in July 2026, Bill Seney and I have been discussing the above topic:

"Bill Seney [said]

I have seen news reports:
https://www.japantimes.co.jp/news/2026/05/26/asia-pacific/south-korea-nuclear-submarine-2030s/

that South Korea [SK] is looking at a nuclear powered variant of the KSS-III. Given that US nuclear subs seem to be getting further and further away and that UK subs are at least 2 decades away is it worth Australia's while to look at a SK option?

Given that [SK] has yet to build a nuclear submarine I could see the project slipping or even facing cancelation, so it is high risk. On the other hand, we know SK can build diesel boats. Perhaps a mixed fleet, with initial deliveries of conventional KSS-III followed by a nuclear variant when available? If the nuclear option is cancelled Australia would still end up with a powerful fleet of conventional submarines.

7/15/2026 10:41 AM
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Pete2 [said]

Thanks Bill [I agree with your 7/15/2026 10:41 AM comment]]

I'll develop your idea as an article probably tomorrow.

I've long theorised here at SubMatts that SK would look to France's K15 LEU reactor for technology transfer. Also that the last KSS-III Batch 2 or Batch 3s would be nuclear powered.

Cheers Pete

7/15/2026 10:53 AM

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Bill Seney [said]

Thanks Pete

Something I forgot to mention in my earlier comment is that the KSS-III is about the same size as the American Skipjack class SSN, so a nuclear KSS-III variant should be technically feasible.
[Pete comment - Yes the Skipjack-class SSN (1956-1990) was indeed KSS-III sized, at ~ 3,075t (surfaced) & ~3,513t (submerged) and the Frenc K15 using, Suffren/Barracuda SSN is ~4,765t-5,300t] 

Also, if Australia wanted to partner with South Korea on SSNs we can provide not just uranium [Australia has the 2nd largest Uranium reserves worldwide] but enrichment technology [Australian invented SILEX] as well, something the Koreans may be interested in.

7/15/2026 10:53 PM
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Pete Comment

Whether the US and its changeable Trump card can play a useful part in SK's (at least 11 year old) nuclear powered submarine program follows in a week. 

Certainly the US has an international law "123 Agreement" hold over SK that transactional Trump will maintain unless SK pays the US the price Trump seeks, that may vary from week to week. 

Despite KNOWING UK's Current SSN Reactors Leaked Radiation UK Chose to rely on Cheaper Computer Testing

I'd like to feature a comment of July 15, 2026, from a possibly new Anonymous:

"I'm not a nuclear engineer but I think the problems with the PWR2 reactor started with cost cutting back in the early 1990s. Previously (PWR1) the UK had built a prototype reactor at Dounreay to check performance and safety. 

For PWR2 this was replaced by using computer simulations instead. See https://www.bbc.com/news/uk-scotland-highlands-islands-51927359

This failed to detect problems with potential cracking on the coolant pipes, which could create a critical failure. This can be combatted with a lot of maintenance effort and full replacement of the pipes during full cycle maintenance. But that is a lot of work - years - each time.
https://www.rusi.org/explore-our-research/publications/commentary/uks-naval-nuclear-reactors-ageing-ungracefully
It seems to be taking all the RN's technical resources to do that for the Vanguard SSBNs. There is not enough left to do Astutes as well, since Vanguard SSBNs appear to have been prioritised.

In my view PWR2 has turned out to be a faulty reactor design."

Pete Comment

Supporting Anonymous' comment above - there was reliance on subsequent computer simulations even though Rolls Royce and the UK Ministry of Defence were aware of nuclear leaks from physical onshore testing.

[An onshore test version of PWR2, was] housed in the [Dounreay's] Shore Test Facility (STF), commissioned in 1987, and went critical with the PWR2's Core G the same year...In January 2012, radiation was detected in the reactor's coolant water, caused by a microscopic breach in fuel cladding. This discovery led to HMS Vanguard being scheduled to be refuelled and contingency measures being applied to other Vanguard and Astute-class submarines, at a cost of £270 million, before similar problems might arise on the submarines. This was not revealed to the public until 2014.^[2][7]

Even though physical testing at Dounreay had revealed serious radiation leaks the UK decided to end further onshore physical testing and instead decided to rely on cheaper computer simulations. 

The Australian Government has committed over A$5 billion in direct investments to expand the UK's Rolls-Royce industrial base and procure critical components for the PWR3 reactors that will power Australia’s future fleet of SSN-AUKUS submarines.

Australia should seriously consider whether it should spend additional $Billions paying for the UK's faulty submarine reactor "SAFETY" regime.

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For further related details see my:

"No UK Astutes Available Again! Safety Fears Demand Lengthy Repairs" of June 8, 2026 at https://gentleseas.blogspot.com/2026/06/no-uk-astutes-available-again-safety.html 

and my "AUKUS Failing TWO - UK cannot deliver on the SSN-AUKUS project" of June 23, 2026 at https://gentleseas.blogspot.com/2026/06/aukus-failing-two-uk-cannot-afford-ssn.html 

Also see a semi-paywalled 2011 UK Guardian article  at https://www.theguardian.com/world/2011/mar/10/royal-navy-nuclear-submarine-reactor-flaws and

a 2014 BBC article at https://www.bbc.com/news/uk-politics-26463923  

Baseless Criticism of China's Missile Test: 1,000s of Ballistic Missiles Tested by the US & UK: Some in Australia

On July 6, 2026, a likely Chinese navy Type 094 SSBN test-launched an SLBM, likely a JL-2 or JL-3, into international waters in the South Pacific.^[7] This was China's second ballistic missile launch into international waters since 1980, following a DF-31 test in 2024. 

Australia's Foreign Minister, Penny Wong, on July 6, 2026, roundly criticised this JL-2 or JL-3 test as "destabilising". 

[Please click HERE] during that time the US has conducted thousands of long and short-range ballistic missile tests, while the UK has conducted roughly 200+ total tests since the Cold War. [1] Australia has been silent when its "friends" test these missiles, all designed to carry nuclear weapons to places like China. 

UK missiles, designed to carry nuclear warheads have been tested in South Australia (see above and here), This included the Blue Streak long range missiles  tested at Woomera, South Australia in 1964 (please scroll down to the Wikipedia table for Woomera launches). Woomera is again open for business for nuclear capable hypersonic missile testing under AUKUS.
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The US, UK and Australia coordinate their testing of nuclear capable missiles of various types, through ongoing programs - like AUKUS Pillar 2 (hypersonic):

• United States: The US has launched thousands of ballistic missiles. For example, just for Intercontinental Ballistic Missiles (ICBMs) and Submarine-Launched Ballistic Missiles (SLBMs)—such as the Minuteman III and Trident II—the US Department of Defense conducts multiple test flights and intercept tests every year. Since the inception of the US ballistic missile program, the number of developmental and reliability test flights ranges well into the thousands. 
  
  
• 
  

  
  
  The US military regularly conducts mainly LGM-30G Minuteman III ICBM tests including one (above) on March 3, 2026 from Vandenberg Space Force Base, California 6,700 km across the Pacific Ocean to the Ronald Reagan Ballistic Missile Defense Test Site on Kwajalein Atoll and the Marshall Islands. (see above and here). 
• Naturally the Australian Government remains silent about these regular US missile tests right into the central Pacific.

• United Kingdom: The UK does not possess land-based ballistic missiles and relies entirely on submarine-launched missiles (SLBMs). Under the 1958 US-UK Mutual Defence Agreement, the UK leases Trident II SLBMs (enough for 8 silos per sub) from the US. Since the introduction of the Polaris and subsequent Trident programs, the UK has conducted approximately 200 to 250 missile flight tests. Some recent UK tests have failed. [1, 2, 3]

Because ballistic missile tests are frequently part of ongoing developmental, operational, and missile-defense evaluations, exact cumulative counts continually grow.

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The largest missile test range in the world is:

-  the Ronald Reagan Ballistic Missile Defense Test Site. Now located primarily in the Marshall Islands (Pacific Ocean), this massive U.S. military facility covers approximately 750,000 square miles (about 1.9 million square kilometers) of ocean and airspace. 

For comparison, the largest land-based missile test range is:

-  the still operational RAAF Woomera Range Complex in South Australia, which encompasses over 122,000 square kilometres (47,000 square miles) of the state. 

Fair seas and following wind, Sam Neill.

Monday brings sad news that New Zealand actor Sam Neill has passed away at the age of 78.

Neill is better known for his role as palaeontologist Alan Grant in the Jurassic Park movie franchise, but for military aficionados, Sam will always be remembered for his portrayal as the Montana-loving Vasily Borodin, second officer to Sean Connery’s Captain Marko Ramius, in the classic 1990 movie adaptation of Tom Clancy’s Hunt for Red October. "Borodin" longed to own a recreation vehicle (RV) once the sub took him to America. On an intelligence bent Neill also played Sidney Reilly in Reilly, Ace of Spies (1983).

Rest in Peace, Sam Neill! 

Pete Comment

OH NO!! Neill was born a New Zealander. But he crossed the ditch (Tasman Sea) to "the Big Smoke" for New Zealanders, known as Australia. As his fame grew he was dubbed Australian. He also owned the Two Paddocks winery near Queenstown NZ. I never did visit that winery :(

Sub Propulsion Systems: LIBs, AIP, DRDO, FC2G, TKMS, IFEP

Over the last week, with the excitement of Canada choosing the TKMS Type 212CD and SubMatts reaching 10 million page views Shawn and Gessler made some very interesting comments that deserve revisiting, 

Because the comments are aimed at a dedicated submarine audience, with considerable assumed knowledge, the comments are frequently without explanation or expansion of all acronyms.

Two of the comments below articles were:

An interesting comment by Gessler of July 7, 2026

"Thanks for the great article [Indonesia starts Scorpene Evo production] Shawn!

It appears the Indonesians may have adopted the Japanese philosophy of Lithium-Ion Batteries (LIBs) being used to replace the AIP system, instead of supplementing it as on the German [TKMS] (and Indian) concepts of operation.

LIBs are particularly useful for high-speed bursts or any such relatively quick discharge of energy, which is something most traditional AIPs (including fuel-cell type) may not be capable of, to the same extent. Where the AIP excels however is in 'drip charging' the system, extending underwater endurance for increased on-station time and so on.

Using the two systems in conjunction (like on Type-212CD or India's upcoming P-75I) would create a lot of operational flexibility for diesel-electric submarines, but of course that comes at additional cost, weight (displacement) & complexity as compared to a LIB-only configuration. So there are several merits for going the LIB-only way unless the operating Navy has very specific requirements that call for a LIB + AIP setup.

In case Indonesia decides to 'upgrade' their Scorpene Evos during one of their scheduled refits a decade or so down the line, I wonder if they'd be interested in DRDO's Fuel-Cell AIP that India has developed for their own Scorpenes, provided the system is finally proven on an actual refitted Kalvari-class (Indian Scorpene) boat by that point. France's Fuel Cell 2nd Generation (FC2G) AIP system is also an option, though it too remains unproven on an actual submarine.

But I guess if Indonesia really wanted AIP, they'd have gone for it from the start. Oh well, who knows what the future holds.

Cheers Gessler"
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Shawn C replied July 8, 2026. "Hi Gessler! Apologies for the late response.

I took [Indonesian shipbuilder] PT PAL's president's claims as brand marketing and the usual "my next boat is better than your current boat" one-upmanship. Note that Singapore already has more submarines than Indonesia (4 in service, 1 working up, 1 fitting out).

I know TKMS has been conducting R&D on LIB batteries since 2014, and refitted a Type-212A in 2024 as a demonstrator - https://thedefensepost.com/2024/10/17/thyssenkrupp-battery-german-sub/

TKMS seems a few years behind the South Koreans and Japanese with LIB technology, but these batteries are supposed to be swappable "without design change" on the Type-209NG - https://www.tkmsgroup.com/submarines/submarine-classes/hdw-class-209

This implies that the Singaporean Invincible-class (Type-218SG) can switch to LIB when they come in for maintenance.

I have been curious of LIB use in military warship power generation for some years, especially as large cruise ships now use such systems to keep the lights on, example: https://corvusenergy.com/products/corvus-dolphin-nxtgen-ess-energy

Singapore's upcoming Victory-class MRCV will use IFEP with diesel power generation, but the use of LIB is not mentioned. LIB will act as a critical backup in damage control, for its ability to smooth out surges and keep high-energy critical systems, like AESA radar, powered."

What Canada's 212CD Sub Choice Means for Germany & Norway

Baltic Defence Review, a highly respectable all weapon types, multinational website, provides July 9, 2026 commentary on Canada's choice of the TKMS Type 212CD. Here are the rough construction timings between the German, Norwegian and Canadian 212CD allies,
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