November 15, 2018

France's Barracuda Delay - Awaiting Improved K15 Reactor

France's future SSN, the Barracuda (first laid down 2007) has been delayed for years due to French delays in developing a new reactor known as the "Improved K15". Of course large existing K15s power the French carrier Charles de Gaulle and France's Triomphant class SSBNs. Put succinctly as France's existing K15 reactor is 10m tall it is too large to fit in the Barracuda's 8.8m diameter hull.

The smaller developing "Improved K15" can be described as a new reactor that will differ not only in size (to fit in the smaller Barracuda hull), but requires other characteristics, including longer periods between refueling, improved natural circulation performance and quietness of operation, improved safety and lower life-cycle costs.

There are no water flow results from the so far not launched Barracuda SSN. So Australia cannot be sure that Australia's Future Submarine (which will have the Barracuda hull shape) will move efficiently and quietly in the water.


So this developing-a-smaller-reactor problem has caused an overall delay in the Barracuda Program. The first Barracuda, the Suffren, was laid down in late 2007 and still hasn't been launched in late 2018.

Delays in the Barracuda SSN Program will (or have) caused delays in Australia's Future Submarine Program. This is important because France's DCNS (now Naval Group) itself identified the Barracuda SSN as the reference design (pumpjet, hydroplanes and all) for Australia's Future Submarine. A crucial area is the hydrodynamic waterflow over the not yet launched submarine's hull and the associated noise the flow makes. There are no water flow results from the so far not launched Barracuda SSN. So Australia cannot be sure that Australia's Future Submarine (which will have the Barracuda hull shape) will move efficiently and quietly in the water.

The Asia-Pacific Defence Reporter's (APDR's) Editor, Kym Bergmann in SEA 1000 - The future submarine project in trouble – and the ‘Barracuda’ reference design, of October 29, 2018 raises the issue that as Australia’s Future Submarine was advertised by DCNS, now Naval Group, as the “Shortfin Barracuda Block 1A.” then:

“ would be helpful for Australian readers to have an update about what has been happening on the [Barracuda SSN] parent program. [When French representatives were asked about progress] The result was silence so complete as to be a metaphor for the supposed stealth characteristics of the submarine itself.”

Later in the article Kym commented:

“Speaking of which, when another small group of Australian journalists were on a French Government media tour a year ago, one of them asked about delays to the Barracuda program and received the answer from Naval Group that – improbably – it was all the fault of the reactor supplier, the majority Government-owned Orano (previously Areva).  French military reactors are unusual because they use commercial grade uranium, unlike enriched uranium favoured by all other navies. Having said that, Orano has a huge amount of experience and since the K15 50 MW reactor for the Barracuda is a derivative of the ones powering the aircraft carrier Charles de Gaulle – themselves a version of the nuclear reactors developed for the Triomphant class SSBNs – so it seems unlikely that this is the real cause of the delay.

Nuclear reactor on a French submarine. Note how the reactor, which is on the right, takes up the whole height/diameter of the submarine - so miniaturising the reactor is essential. (See diagram on page 200 of Peter Lobner's Marine Nuclear Power 1939 – 2018_Part 4_Europe & Canada (PDF 20 MB).)


Fortunately GhalibKabir has pointed me to a July 2018 body of work by submarine reactor expert Peter Lobner which reveals the K15 reactor issue is still valid. Basically the problem with the existing K15s in the French carrier Charles de Gaulle and in French Triomphant class SSBNs are that they are too large to fit in the smaller Barracuda SSN hulls. Put succinctly France's existing K15 reactor, at 10m tall, its too large to fit in the Barracudas' 8.8m diameter hulls.

Peter Lobner's Marine Nuclear Power: 1939 - 2018, at, runs to 1,000s of pages. But the relevent section on France's latest naval reactors is in Marine Nuclear Power 1939 – 2018_Part 4_Europe & Canada  (PDF 20 MB). Don't be downhearted when you see that Part 4 alone is 364 pages. The relevent pages I focus on concentrate on the Improved K15 on page 179 and then 189 to 208

As well as smaller size there are other improvements to the K15 which make it (or more correctly will make it) a new reactor. It is known for public relations, political and defence program cost saving reasons as the "Improved K15". Lobner explains that the prototype of the Improved K15 has not even gone critical as at mid-2018 in the French naval reactor prototype test center at CadaracheAs there is no operating Improved K15 actually in a Barracuda (these subs are still in a shed) we need to rely on land based prototype reactor reports .

Lobner Page 207 explains the existing K15 vessel is about 10m tall. So, yes, it does fit into the Triomphant class SSBN's 12.5m diameter hull and of course two K15s fit into the much larger French carrier Charles de Gaulle.

Page 208 states the need to "Reduce the physical size of the [Improved K15 reactor] so it can fit on a Barracuda-class SSNs which has an outer hull diameter of 8.8 m...


The detail, in context, in Marine Nuclear Power 1939 – 2018_Part 4_Europe & Canada  (PDF 20 MBis important.

Page 179 with table "Naval reactor [land] prototypes" when put fully into English the:
-  "RNG" the "K15" drives the Triomphant class SSBN and carrier Charles de Gaulle, and
-  "RES" land prototype for the "improved K15" "Originally intended to replace [the K15] in about 2009. Not yet operational in 2018." then

Page 189: "The RES test reactor is an upgraded version of the K15 [reactor] that currently is operating on four Le Triomphant-class SSBNs and the aircraft carrier Charles de Gaulle. The upgraded [ie Improved] K15 will be the [reactor] for the new Barracuda-class SSNs."

Page 190: "RES [land reactor] prototype...Key milestones...As of mid-2018: No report yet of initial criticality."

Page 197: "French naval nuclear reactors...Improved K15 integral PWR for the Barracuda-class SSNs, expected to use LEU fuel."

Page 207: "K15 integral PWR...The complete K15 vessel is about 10 m (32.8 ft.) tall and 4 m (13.1 ft.) in diameter. Le Triomphant-class SSBN hull outer diameter is 12.5 m (41 ft.)."

Page 208: "Improved K15 integral PWR...The design is based on the K15 integral PWR [reactor]. This reactor was expected to be tested in the RES prototype facility at Cadarache. However, significant delays have been encountered in the completion of RES, and, as of mid-2018, initial criticality of the reactor prototype has not yet occurred."

Page 208 continues
Objectives for the improved K15 include:
Reduce the physical size of the [improved K15 reactor] so it can fit on a Barracuda-class
   SSNs, which has an outer hull diameter of 8.8 m (28.9 ft). The complete K15 vessel is
   about 10m (32.8 ft.) tall.
-  Improve the [reactor's] natural circulation performance and quietness of operation.
-  Operate with LEU fuel and deliver thermal power comparable to the K15.
-  Achieve 10 years of operational activity between refueling.
-  Reduced the time needed for refueling (target 3 months vs. 5 months currently).
-  Improve the human-machine interfaces with the instrumentation, control and protection systems.
-  Reduce life-cycle costs (construction + operation).
-  Improve safety.
-  Improve availability.

The first Barracuda-class SSN is expected be launched in the 2018 –2019 timeframe."


Note that even if the Improved K15 prototype at Cadarache goes critical in late 2018 that does not make an Improved K15 instantly ready to be placed in a Barracuda hull and then go critical. It may take years longer to propel this first Barracuda with subsequent design, building and testing delays for Australia's Future Submarine Program. 



Anonymous said...

Mr. Lobner wrote that the RES reactor is the prototype of the improved K15. I am unsure as to how correct is that statement. RES in French is a test reactor, reacteur d'essai.

The following French text:
"Le réacteur d'essai (RES) est représentatif des chaufferies nucléaires compactes qui propulsent les sous-marins français et le porte-avions Charles de Gaulle. Il permet de reproduire le fonctionnement des chaufferies embarquées, en éprouvant les matériels dans des conditions d'endurance encore plus contraignantes. Il contribue ainsi à accroître leur disponibilité opérationnelle et à démontrer leur sûreté. Les prédécesseurs du RES étaient des prototypes destinés à mettre au point les concepts successifs de chaufferies. Le RES est un outil expérimental de recherche & développement, doté d'une importante instrumentation spécifique au cœur du réacteur. Les données acquises permettront d'améliorer les simulations pour adapter les chaufferies aux besoins futurs des bateaux, tout en rendant encore plus robuste la démonstration de sûreté. Le RES contribue également au maintien des compétences des équipes en charge de la propulsion nucléaire."

clearly states that the RES is only an experimental research reactor. I do not disagree that the K15 will need to be shrunk to fit within the Suffren's narrower beam. I speculate the engineers likely move the steam generator which is normally on top while keeping the core the same to shrink the height? On various French blogs, I only read about K15 150MW being used in the Suffren, I have not found any mention about an improved K15. At the same time, Naval Group has shown a photo in dry dock of the completed Suffren, that more or less says the design and installation of the K15 inside the Suffren is finished?

I also read on French blogs, unsure how correct things are, that below ~16knots, the prop shaft is driven by electric motors while above that speed, the turbine is coupled to the prop shaft via a gearbox. This implies the Suffren is much quieter below 16kts. You still have the noise from the reactor.

GhalibKabir said...

I wish I could force all the major media houses in India esp. the likes of ndtv, to read this article twice over before they spout retarded nonsense. They do so all the time and incessantly display their illiteracy on every major weapons platform on prime time.

Common Sense and Critical Thinking are probably the rarest commodities on planet earth. if both were foodstuff, then media houses would rank somewhere between extreme undernourishment and outright starvation on the deprivation scale.

Lobner's Magnum Opus is a brilliant comparison tool that shows in remarkable detail how the struggles by the six navies operating nuclear boats were very similar in many respects.

The K15 saga is no different as the balance between longer refueling cycles while being based on a LEU core against the constraints in beam size is considerable.

Petra for Pete's SMI Network said...

Thanks GhalibKabir

Yes it is critical to be able to squeeze the whole height of the Improved K15 Reactor into the Barracuda/Suffren class.

The entire nuclear reactor pressure vessel (into which are the nuclear reactor coolant pipes on top + the reactor core on bottom) needs to be accommodated.

With the diagram in the article here taken from page 200 from Lobner.

The French Navy (quoted in ) is hoping to do a refuel in "3 months vs. 5 months currently".
But if that means the second group of Australian Future Submarines (assuming they're SSNs) have to travel to and from France to refuel this is still a major operational problem.



GhalibKabir said...

The refueling of the Aussie SSNs has to happen in Australia else it is sort of pointless to keep a fleet of SSNs, if they are routinely not available due to core refueling.

Considering the core will be a LEU based one, NPT provisions and common sense based oversight rules should allow for responsible senior western allies like Australia to be treated like adults and allow them to refuel their own boats in their own harbours.

sending the SSNs from Sydney or Perth to Cherbourg is a terrible waste of money and time. The one thing I do hope they can do is modularize the Barracuda just like the Scorpene so that just like Scorpene AIP modules can be plugged in and out, they should be able to fuel the reactor say within 10 weeks using readily pluggable modules.

PS: I had a great time in Sydney last week. was visiting for business.

Petra for Pete's SMI Network said...

Hi GhalibKabir [at 20/11/18 7:39 PM]

Yes, refueling in Australia would also be necessary to avoid bilateral scheduling clashes if a French Barracuda also required LEU refueling in France at the same time.

Also the ability for Australia to refuel would be an essential part of the independence or autonomy of what would be Australia's most sensitive and expensive weapons system.

Far easier, indeed, for Australia to justify "proliferation" of an LEU reactor rather than a US/UK HEU 90+% "bomb grade" reactor.

Refueling in/near Fleet Base West, Rockingham, whould be much easier PR wise than refueling in Adelaide or Sydney Harbour. Even better if refueling was in the form of plugged/sealed modules rather than "loose" LEU.

PS. Glad you enjoyed Sydney. Sorry I live too far away to meet.



GhalibKabir said...

agree with you said... but,proliferation, me thinks lost whatever credibility it had in 2004 when China was admitted to the NSG despite serial proliferation since 1979. Akin to the village arsonist being elected fire chief.

(by 1981 within days of inauguration Reagan had KH satellite pictures of Lop Nor test site in Northern extremes of China, where a pakistan air force C-130 was being loaded with arguably first few dozen kilos of weapons grade chinese HEU. He chose to reward pakistan with F-16s instead).

So, Australia with its exemplary record needs no justification to get LEU based SSNs on outright purchase or on lease..the least any busybody could do is take a hike up Mt. Everest. Considering the second island chain defense plan of the PLAN, SSNs or ideally SSGNs are a practical need (the US can give 1000+ km range LACMs under MTCR). Also if proper oversight and EUMA can be signed, I cannot see why transfer of modular plug HEU reactor is not possible. Australia could get ready made nuclear reactor modules and return when done.

China will under some pretext lease SSNs to pakistan in a few years anyways. Might as usual being 'Right'. This geopolitical hypocrisy is on expected but regrettable lines of thought.

Petra for Pete's SMI Network said...

Hi GhalibKabir [at 22/11/18 12:55 AM]

On the LEU vs HEU Australia choices are not only dictated by international public and UN/IAEA opinion but the opinion of the very sensitive Australian public, who are very timid about all things nuclear.

So what the heck it would be as hard to "sell" propulsion by LEU to the Oz public. So, yes, may as well go the whole way and choose HEU.

The following is a 2009 Australian article indicates that Tomahawks for Australia has long been officially floated, but little public progress made. on July 1, 2009 reports:

"Now, however, the [Australian Government of Prime Minister Rudd, in the 2009 Defence White Paper] has announced its intention to deploy land attack cruise missiles not only on the Future Submarine that will replace the Collins class but also on the eight Future Frigates that will eventually supercede the Anzac class, and, of more immediate interest, on the [VLS of the] RAN's three air warfare destroyers (AWDs)."

China leasing SSNs to Pak would at least spur India to build those SSNs and spur Australia to buy SSNs (or better still SSGN "Baby Boomers").