Rumoured "mini-nuke/diesel" Submarine SSK-N(?) thread

[tphuang]

SSKN will always be quieter than a full SSN because there is no gearbox, which is a huge source of noise and also a headache for Chinese industry, which has always been weaker on precision mechanical assemblies than electronics. Imperfections in the gears can cause noise, and as the gears rotate, the noise is periodic. This creates a detectable signal for the specific gearbox. bad.

SSKN mechanically decouples the engine from the drive shaft. This means no large, hull coupled gearbox needed, and no source of noise other than the reactor itself.

yes, not having reduction gear simplifies what you need to install inside the submarine and removes a source of noise. Not havng coolant pump would do so too.

From what I was read before, main engines, turbine generators & hydraulic pumps are all major source of noise & maybe louder than coolant pump. It's not clear to me for a small reactor, what else you can simplify or eliminate. Clearly, I'm not a nuclear engineer, but even a small reactor that generates 1MW of energy still needs a steam turbine.

The concern is that you are fitting this in a much smaller hull & how much noise that generates (more or less than a stirling engine?) and how well you can isolate it? Again, they may well have done the calculation already and found that it is possible with current tech and that they can completely isolate it inside its compartment. I don't have the background to guess more than this.

 

[tacoburger]

Any idea of how many the PLAN is planning to build? And their cost compared to a traditional SSN/SSKN?

 

[Hitomi]

yes, not having reduction gear simplifies what you need to install inside the submarine and removes a source of noise. Not havng coolant pump would do so too.

From what I was read before, main engines, turbine generators & hydraulic pumps are all major source of noise & maybe louder than coolant pump. It's not clear to me for a small reactor, what else you can simplify or eliminate. Clearly, I'm not a nuclear engineer, but even a small reactor that generates 1MW of energy still needs a steam turbine.

The concern is that you are fitting this in a much smaller hull & how much noise that generates (more or less than a stirling engine?) and how well you can isolate it? Again, they may well have done the calculation already and found that it is possible with current tech and that they can completely isolate it inside its compartment. I don't have the background to guess more than this.

They might use a elongated hull design of the current 039C to accommodate the nuclear reactor and whatever noise reduction tech needed, assuming they need any in the first place.

Actually on a side note, would it be noticeable if the 039 outer hull shape was retained but internally it is converted to a single hull and how feasible would that be?

 

[Stealthflanker]

I suppose by "unibody" it means it doesn't need a separate containment vessel, possibly due to its lower pressure and temperature?

This should means the steam generator and the reactor vessel is unified. Similar approach as French naval reactors and recent Russian Yasen class.

Previously, particularly for American boat, the reactor and steam generator are in separate compartment, the reason being so that it can be easily inspected. This however adds bulks to the reactor, something which could be undesired for a small submarine. Soviet and French opted for integrated steam generator for their small boats namely Rubis and P.705 "Alfa" class.

Actually on a side note, would it be noticeable if the 039 outer hull shape was retained but internally it is converted to a single hull and how feasible would that be?

You need a new Submarine for this. The "outer hull" or "Light hull" for a double hulled submarine is not empty, it contains the frames to support the structures and various tanks, especially the MBT (Main Ballast Tank). You cannot change the layout of the internal hull without also changing those which amounted to building a new submarine.

-------

This Chinese program, really reminds me of the US's SSN-597 "Tulibee"

 

[Hitomi]

This Chinese program, really reminds me of the US's SSN-597 "Tulibee"

IIRC the Tulibee wasn't actually hybrid powered submarine like this Chinese proposal but was purely nuclear powered with a turbo-electric drive for noise reduction and that the SSKN designation at the time to the USN meant a smaller and cheaper nuclear powered attack submarine which is now obsolete and not an SSKN in current military discourse we are talking about here. The closest would actually be the Canadian attempt to upgrade their Oberon class diesel electric submarines with the SLOWPOKE reactor.

 

[Stealthflanker]

IRC the Tulibee wasn't actually hybrid powered submarine like this Chinese proposal but was purely nuclear powered with a turbo-electric drive for noise reduction and that the SSKN designation at the time to the USN meant a smaller and cheaper nuclear powered attack submarine which is now obsolete and not an SSKN in current military discourse we are talking about here. The closest would actually be the Canadian attempt to upgrade their Oberon class diesel electric submarines with the SLOWPOKE reactor.

Does it tho.. ? the description i see from this thread so far is the sub will be fully nuclear powered instead of "hybrid" scheme.

If that Oberon upgrade there is the closest then, the nuclear reactor essentially become AIP.

 

[Dante80]

This is a pretty interesting concept (replacing AIP technologies in a SSK with a -possibly subcritical- small reactor), let's see how it unfolds.

 

[snake65]

Soviet Union had a Juliet class Diesel SSG augmented by a small reactor but it remained rather experimental. Pr.705 is by no means the smallest Soviet nuclear sub, there are several special purpose deep diving subs ranging from several hundred to 1500 tons.

 

[tphuang]

Soviet Union had a Juliet class Diesel SSG augmented by a small reactor but it remained rather experimental. Pr.705 is by no means the smallest Soviet nuclear sub, there are several special purpose deep diving subs ranging from several hundred to 1500 tons.

from what I heard, that SSG had reactor in separate pressure hull to drive the shaft. That reactor generates 600kW of power

This SSK-N will be different, it should just be generating electricity and the boat itself runs of battery still. And in this case, I think reactor will be in same hull as everything else. My guess is that they will want more than 600kW power (I've been saying 1 MWe from a 3 to 4 MWt reactor).

This is a pretty interesting concept (replacing AIP technologies in a SSK with a -possibly subcritical- small reactor), let's see how it unfolds.

Stirling only generates 320kW of power and you run out of liquid nitrogen after 2 weeks even if it doesn't go that fast. In this case, I'm guessing that nuclear reactor will actually be the primary source of charging battery & diesel engine will be the backup

 

[Chavez]

This small submarine will make it at par with the french rubis class small ssn.