French Anonymous made interesting commentson March 20, 2023. Pete has done some editing and Pete's additional comments are in [...] brackets.
These are rumours from the Indian pressbut without any info from the French side..
In any case I am not sure what it means.
The design and the deployment/military uses philosophies of the French SSN are quite different from the Russian or US views. The Chineseare using an approach to LEU that sounds similar to the French one apparently, without much public data.
- The LEU/HEU debate has been well documented. The French system is really an extension of their civilian PWR reducing hugely the cost, using the same critical civilian safety regulation and relying on the civilian fuel cycle assets and economics. The legal need to inspect an empty reactor every 10 years (using robots) allows the French Navy to have very compact designs with the steam generator within the reactor (a critical interface changed every 10 years, including in HEU system, anyway[??] )
[ Peter Lobner page 206 (of a large .PDF) reports regarding France’s K15 reactor used in the Barracuda SSN:
“Fuel: Much higher uranium enrichment than in the [outgoing Rubis-class SSNs] CAS-48 reactor (which is 7% enrichment). Some sources claim K15 uses HEU fuel at > 90% enrichment.”]
and to develop robots, facilities (as in Civilian PWR, changed every 2/3 years) to change the fuel quickly (2/3 weeks) and to allow easy dismantling
The USN on the contrary puts a huge premium on "sealed for life core" because they have a long positive learning curve/experience, they have still a large inventory of HEU (Nuclear weapons converted, the US stopped the production of HEU [but the US is reported to be restarting HEU enrichment at a new SILEX trial plant in Kentucky] and because most important this limits the number of USN facilities needed (equipment, people, political local sensitivities) worldwide to support the fleet as the USN cannot piggy back on the civilian (See US senate studies).
This leads to much larger US SSNs (due to the need to deploy vertical rods to slow down or stop reactor fission, the heat exchanger is outside, there is limited U235 volumetric density/loading for obvious safety reasons, making reactors typically twice the size, much higher cost and larger nuclear engineer/technician/damage control crew needed. Once you have large assets you try to use them beyond a traditional sub mission and you incorporate more and more cruise missile for instance (leading to VLS in large numbers).
- The French deployment has the objective of having SSNs to protect French SSBNs, protect the French surface fleet and to intercept enemy naval assets.
- This means emphasis on very silent French SSNs with the best sonars and torpedoes. They operate tactically in an electric mode with very large permanent magnet motors (4 to 10 MWe range) and the associated converter/drives. This is more difficult for larger US and UK SSNs, driven by steam turbines. The steam drives turbogenerators while the steam turbine is used essentially for quick strategic moves (deep and at 25+knots) in the Barracuda class SSNs.
By the way the French reactors can remain critical using natural cooling in the silent mode as reported (critical means that the neutrons level is constant, at any, very low or very high, power.). The French do not have the resources including human of having large boats
[Australia, with the smallest population and GDP in the nuclear sub world has even less human resources than France. Yet Australia is buying Virginia SSNsthat require more than twice the crew (135 men) than French Barracuda SSNs (60 men).]
Barracudas don’t have redundant cruise missile systems for land attack ([which may be just 6] MdCN missiles on a Barracuda, fired via the torpedo tubes. [Just 6] is a marginal amount compared numbers of land attack missiles on French surface ships or airforce platforms. France can’t afford US style inter-services rivalries [where the US Submarine Service (using its SSNs and SSGNs) competes bureaucratically to be permitted to launch more Tomahawk land attack missiles than US destroyers or cruisers, or more than US aircraft dropping missiles/bombs. For example, in the 2003 invasion of Iraq and 2011 invasion of Libya (for Libya see US "Forces Committed")].
In the case of Brazil, Brazil has developed an intermediate reactor solution of its own, using the highest level LEU (just under 20% U235) to contain costs while refueling its future SSN after 20/25 years. It is the electric drive mode that Brazil is buying from Naval Group to use an enlarged Scorpene hull for its future SSN (no pump-jet as far as I know).
Is the Indian Navy interested in the electric propulsion that the Russian or the US have not explored as much? in the pump-jet? Does India want to move to a civilian compatible solution? Is this linked to an Indian civilian Nuclear strategy discussed with the French at the same time? [India and France propose to construct6 French designed European Pressurised Reactors (EPRs) reactors at Jaitapur, India), where India would need to have a complete control of its fuel cycle if India is serious about civilian nuclear.
It is not clear at all [about India's submarine and civilian power reactor sector integration plans] but these are interconnected to a large extent.
Is India to build or buy SSNs in the 10,000 tonne [Russian Akula SSN tradition] or in the [French Rubis SSN or large Scorpene hull style] 3,000/4,000 tonne ranges? [or some size in between?]
PETE COMMENTS
On Chinese use of LEU reactors and any Australian compatibility to France's SSN setup will be sent to Donors next week.