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

[plawolf]

Would Wuchang be capable of producing nuclear powered submarines even though they are of similar size to the SSK they are already building? Since there don't seem to be any facilities for fueling the reactors right now or are there any plans for expansion that we can tell

Unless they are trying to be silly, they would be building the nuclear element as a self-contained unit that would not need any specialist equipment to install. The whole point of an SSK-N is to keep as much of the SSK as possible, otherwise you might as well just go full SSN.

 

[tphuang]

Unless they are trying to be silly, they would be building the nuclear element as a self-contained unit that would not need any specialist equipment to install. The whole point of an SSK-N is to keep as much of the SSK as possible, otherwise you might as well just go full SSN.

And how would you do that exactly?

Try to Be specific when it comes to what is needed for a nuclear reactor here and what other machineries are needed?

"The concern for mini nuke once you get past 1IC is not frigates, but SSNs"

just the opposite

mini nuke is the silent hunter once he is in his patrol zone

you think Chinese submarines are more concerned about frigates than SSNs?

 

[ACuriousPLAFan]

China already have the full SSK production and operational infrastructure in place. More importantly, its SSK production base is distinct from its SSN production, so simultaneous production has almost no direct opportunity cost as one more SSK-N doesn’t have to mean one less SSN.

Yes, it’s wasteful, but in war, overkill is infinitely preferable to defeat.

The PLAN can rapidly replace its existing SSKs with SSK-Ns and be able to spin those up into combat capable units far faster than it can spin up additional SSN boats. That’s not just in terms of production timescale, but also crew training and experience.

I view the SSK-N as similar to the leap from a J11 to J16. It’s a quantum leap in capabilities, but you can still use a lot of existing legacy support facilities and pilots don’t need to learn a totally new way of fighting. Whereas SSNs are more like 5th gens that gives you an entirely different class of capabilities. And just like how the PLAAF is dual procuring legacy and 5th gens, there is every chance the PLAN will do the same with SSK-Ns and SSNs.

Unless they are trying to be silly, they would be building the nuclear element as a self-contained unit that would not need any specialist equipment to install. The whole point of an SSK-N is to keep as much of the SSK as possible, otherwise you might as well just go full SSN.

Now that you mentioned it:

At the present state (and for the foreseeable future) - Huludao is capable of launching 3-4x SSNs per year.

Besides, assuming that both Wuchang and (to a more certain degree) Jiangnan are capable of building SSK-Ns, I'd put the capability of 1-3x SSK-Ns per year for both shipyards (that is, 1x for Jiangnan and/or 1-2x for Wuchang), depending on how urgent the PLAN needs SSK-Ns to supplement (before replacing) their SSK fleet.

Tallying all three shipyards, this means a combined total SSN + SSK-N launch capability of at least 4x boats per year (3x SSNs + 1x SSK-N) and at most 7x boats per year (4x SSNs + 3x SSK-Ns). With sustained production rates for all the involved shipyards, this translates into the potential of 40x - 70x boats being launched in a decade.

(Technically speaking, without constructing any new SSBN, Huludao could potentially add another 1x SSN to the tabulation, meaning a theoretical maximum of 8x boats per year. However, let's keep that additional SSN out for the sake of this discussion.)

In contrast, the US aims to raise the production rate of the Virginias to 2x boats per year by 2028, 2.3x boats per year in the early-2030s and potentially 2.5-3x boats per year later on.

The last time the US had comparable build rates of nuclear submarines (of all types) was in the 1960s, followed by the 1980s and 1970s.


(From the latest Binkov Battleground's Virginia vs 093B video)

UUVs and AUVs aside, it's only going to be extremely hard for the US to attempt such stunts again like what they did during the heat of the 1st Cold War. But even so - Nowadays, China is a major player in the UUV and AUV domain, too.

That is to say - Even if/when the 093B is incomparable to the early-Virginias, the mere potential number (and thus, subsurface firepower delivery capabilities) of the PLAN SSNs + SSK-Ns that is concentrated in the Western Pacific and Eastern Indian Oceans in the coming years will become increasingly staggering, if not daunting for the opposing side.

 

[plawolf]

And how would you do that exactly?

Try to Be specific when it comes to what is needed for a nuclear reactor here and what other machineries are needed?

That’s a rather disingenuous question, like expecting people to explain how the J36 addresses its core technical design challenges.

I don’t need to solve the design challenges because there are teams of top engineers and designers doing that work. And my ability or lack of to explain how they achieved their breakthrough has absolutely no bearing on whether or not they can achieve the breakthrough. The very fact that they are building the thing means they have already solved the core design challenges.

But based on open source existing technologies, there are broadly two possible paths, one is a micro-reactor using traditional thermal power generation, and they other is nuclear batteries.

Micro reactors would be more simple in terms of off-the-shelf tech, but will have basically the same engineering challenges of true SSNs in terms of noise management. And most critically, would require fundamentally different internal layouts of the subs. Taking away much of the benefits of dual running SSN and SSK-N production.

Unless they have managed to achieve incredible levels of miniaturisation of nuclear reactors and all associated ancillary equipment to allow it all to be self contained in the space of a diesel generator and fuel tanks, this seems a poor choice as it wouldn’t be that much simpler or cheaper compared to building true SSNs, all to get a very watered down SSN-Mini that doesn’t come close to approaching the capability of true SSNs.

If they truly went down that path, I would have expected them to call the thing SSN-M as opposed to SSK-N.

The other option of switching to nuclear batteries would seem like the most likely approach. Existing operational designs already claim to be able to scale to kilowatt range, so it’s not unreasonable to think megawatt output levels is attainable through bigger scaling, or a fundamentally different core design focused on power output instead of flexible.

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Depending on their calculations, they can scale down on the diesel backup generator and fuel tanks, or delete them entirely to add more nuclear battery power generation.

Another reason I think this is the most likely engineering route taken is in the use case. SSN-M should be able to operate like true SSNs, just maybe with lower peak and sustained top speeds.

Whereas an SSK-N with n-batteries will operate much more like a traditional SSK, transiting at very low speeds and waiting silently in ambush while charging its batteries for the brief burst of peak power needed when it launches its attack. The biggest benefit is n-batteries are silent, so no noise management mitigation is needed. They can pack the n-batteries between the inner and outer pressure hulls if they wanted and it won’t add any noise to the boat, with the only limiting factor being the pressure and temperature rating of the n-batteries themselves. Making it possible to retrofit existing SSKs or add them to the design of new builds with minimal design mods needed. That is the core justification for SSK-N, as an evolutionary leap or even MLU option for traditional SSKs as opposed to a SSN-M.

 

[plawolf]

Now that you mentioned it:

At the present state (and for the foreseeable future) - Huludao is capable of launching 3-4x SSNs per year.

Besides, assuming that both Wuchang and (to a more certain degree) Jiangnan are capable of building SSK-Ns, I'd put the capability of 1-3x SSK-Ns per year for both shipyards (that is, 1x for Jiangnan and/or 1-2x for Wuchang), depending on how urgent the PLAN needs SSK-Ns to supplement (before replacing) their SSK fleet.

Tallying all three shipyards, this means a combined total SSN + SSK-N launch capability of at least 4x boats per year (3x SSNs + 1x SSK-N) and at most 7x boats per year (4x SSNs + 3x SSK-Ns). With sustained production rates for all the involved shipyards, this translates into the potential of 40x - 70x boats being launched in a decade.

(Technically speaking, without constructing any new SSBN, Huludao could potentially add another 1x SSN to the tabulation, meaning a theoretical maximum of 8x boats per year. However, let's keep that additional SSN out for the sake of this discussion.)

In contrast, the US aims to raise the production rate of the Virginias to 2x boats per year by 2028, 2.3x boats per year in the early-2030s and potentially 2.5-3x boats per year later on.

The last time the US had comparable build rates of nuclear submarines (of all types) was in the 1960s, followed by the 1980s and 1970s.

View attachment 147064
(From the latest Binkov Battleground's Virginia vs 093B video)

UUVs and AUVs aside, it's only going to be extremely hard for the US to attempt such stunts again like what they did during the heat of the 1st Cold War. But even so - Nowadays, China is a major player in the UUV and AUV domain, too.

That is to say - Even if/when the 093B is incomparable to the early-Virginias, the mere potential number (and thus, subsurface firepower delivery capabilities) of the PLAN SSNs + SSK-Ns that is concentrated in the Western Pacific and Eastern Indian Oceans in the coming years will become increasingly staggering, if not daunting for the opposing side.

That’s just existing, established shipyards. There are many more smaller commercial yards that can either make SSK-Ns entirely on their own in a war economy scenario, or at a minimum work as subcontractors for parts and modules that can vastly boost SSK-N production numbers if needed.

That, I think, is the chief consideration behind the whole SSK-N project.

And SSK-Ns do hold a uniquely useful and relevant edge compared to even SSNs to make them an invaluable asset during a total war scenario in the Pacific.

SSKs are ambush predators best served at camping key geographical choke points or area of interest. Once on station, they can camp better than SSNs due to their lower noise levels while stationary or at very low speeds. An SSK-N basically retains all that while removing the chief drawback of traditional SSKs of short endurance and time on station without needing to run noisy diesels to recharge.

SSNs are roaming hunters that are best suited to cruising around at high speed hunting for targets.

Having SSKs frees up the PLAN’s SSNs from defensive duties and can focus on offence and fleet escort.

The biggest headache for the PLAN is that as they win the initial exchanges and push further out into the Pacific away from Chinese shores, the tyranny of distance starts to work against them and in favour of the USN.

SSK-Ns will help to mitigate that by allowing the PLAN to essentially take and hold ground in the sea. Obviously it won’t be like traditional land warfare with a literal line of SSK-Ns running the length of the Pacific, but having large numbers of SSK-Ns positioned throughout the Pacific can vastly increase the risk and costs to the USN of running WWII German U-boat style hunting tactics behind the main naval engagement lines.

 

[tphuang]

That’s a rather disingenuous question, like expecting people to explain how the J36 addresses its core technical design challenges.

I don’t need to solve the design challenges because there are teams of top engineers and designers doing that work. And my ability or lack of to explain how they achieved their breakthrough has absolutely no bearing on whether or not they can achieve the breakthrough. The very fact that they are building the thing means they have already solved the core design challenges.

But based on open source existing technologies, there are broadly two possible paths, one is a micro-reactor using traditional thermal power generation, and they other is nuclear batteries.

Micro reactors would be more simple in terms of off-the-shelf tech, but will have basically the same engineering challenges of true SSNs in terms of noise management. And most critically, would require fundamentally different internal layouts of the subs. Taking away much of the benefits of dual running SSN and SSK-N production.

Unless they have managed to achieve incredible levels of miniaturisation of nuclear reactors and all associated ancillary equipment to allow it all to be self contained in the space of a diesel generator and fuel tanks, this seems a poor choice as it wouldn’t be that much simpler or cheaper compared to building true SSNs, all to get a very watered down SSN-Mini that doesn’t come close to approaching the capability of true SSNs.

If they truly went down that path, I would have expected them to call the thing SSN-M as opposed to SSK-N.

The other option of switching to nuclear batteries would seem like the most likely approach. Existing operational designs already claim to be able to scale to kilowatt range, so it’s not unreasonable to think megawatt output levels is attainable through bigger scaling, or a fundamentally different core design focused on power output instead of flexible.

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Depending on their calculations, they can scale down on the diesel backup generator and fuel tanks, or delete them entirely to add more nuclear battery power generation.

Another reason I think this is the most likely engineering route taken is in the use case. SSN-M should be able to operate like true SSNs, just maybe with lower peak and sustained top speeds.

Whereas an SSK-N with n-batteries will operate much more like a traditional SSK, transiting at very low speeds and waiting silently in ambush while charging its batteries for the brief burst of peak power needed when it launches its attack. The biggest benefit is n-batteries are silent, so no noise management mitigation is needed. They can pack the n-batteries between the inner and outer pressure hulls if they wanted and it won’t add any noise to the boat, with the only limiting factor being the pressure and temperature rating of the n-batteries themselves. Making it possible to retrofit existing SSKs or add them to the design of new builds with minimal design mods needed. That is the core justification for SSK-N, as an evolutionary leap or even MLU option for traditional SSKs as opposed to a SSN-M.

Well, I think we already established earlier on in this thread that this sub mostly likely uses a small reactor (possibly Thorium) and coupled with Stirling engine for converting the energy into electricity.

Of course, they would also need diesel backup and small fuel tank (all nuclear subs do that) and that will take additional space.

The Stirling itself will likely be the largest ever Stirling engine they install in a submarine (MW class vs 320kW on 039C).

Nuclear reactor process itself to the best of my knowledge doesn't work like a diesel engine, so different components are needed to support it. But let's say Stirling solves that problem (I have no idea the answer to whether or not steam engine is still needed here). But the Stirling itself will be large. You need a larger battery pack since it's expect to go faster than your conventional sub. I would also imagine you need a more complex and larger electric propulsion system, drive and reduction gear since the power requirement is higher. You also need a more complicated atmospherical control since you want the sub to be able to remain underwater without needing to ventilate.

Reactor itself needs to be isolated. The fuel installation part needs to be in its own specialized facility. I have no idea if that's going to be in WuChang (but more likely in JN or something like that, since China doesn't like putting reactors in inland locations). So then it raises the question of how you move it downstream Yangtze River.

So, I'm having real trouble figuring out how this is going to self contained. I'm clearly not the most technical person in this nuclear reactor + sub area, so this is the best I can come up with. This is a good place to seek new ideas and knowledge.

 

[AndrewS]

Reactor itself needs to be isolated. The fuel installation part needs to be in its own specialized facility. I have no idea if that's going to be in WuChang (but more likely in JN or something like that, since China doesn't like putting reactors in inland locations). So then it raises the question of how you move it downstream Yangtze River.

So, I'm having real trouble figuring out how this is going to self contained. I'm clearly not the most technical person in this nuclear reactor + sub area, so this is the best I can come up with. This is a good place to seek new ideas and knowledge.

The biggest risk is a nuclear meltdown and self-sustaining fission chain reaction.

But if we're talking about a 1MW reactor that only runs a few months per year whilst on patrol, it doesn't look like there is enough nuclear fuel to achieve critical mass.

So in terms of [risk] x [consequences], I don't think there would be an issue with where the reactors are fuelled, nor with transporting the reactors, whether that is along the Changjiang river or by road/rail.

 

[plawolf]

Well, I think we already established earlier on in this thread that this sub mostly likely uses a small reactor (possibly Thorium) and coupled with Stirling engine for converting the energy into electricity.

Of course, they would also need diesel backup and small fuel tank (all nuclear subs do that) and that will take additional space.

The Stirling itself will likely be the largest ever Stirling engine they install in a submarine (MW class vs 320kW on 039C).

Nuclear reactor process itself to the best of my knowledge doesn't work like a diesel engine, so different components are needed to support it. But let's say Stirling solves that problem (I have no idea the answer to whether or not steam engine is still needed here). But the Stirling itself will be large. You need a larger battery pack since it's expect to go faster than your conventional sub. I would also imagine you need a more complex and larger electric propulsion system, drive and reduction gear since the power requirement is higher. You also need a more complicated atmospherical control since you want the sub to be able to remain underwater without needing to ventilate.

Reactor itself needs to be isolated. The fuel installation part needs to be in its own specialized facility. I have no idea if that's going to be in WuChang (but more likely in JN or something like that, since China doesn't like putting reactors in inland locations). So then it raises the question of how you move it downstream Yangtze River.

So, I'm having real trouble figuring out how this is going to self contained. I'm clearly not the most technical person in this nuclear reactor + sub area, so this is the best I can come up with. This is a good place to seek new ideas and knowledge.

I think if you find yourself trying to reconcile two impossible factors, you need to re-examine the assumption that created this impossible position in the first place.

Much of the massive size requirement you are struggling with is rooted in the assumption that the SSK-N needs to go fast. That speed requirement is what is driving the power requirement that requires a massive Stirling engine; and also the larger battery pack; bigger propulsion system, more complex electrical system; drive train and gearing, basically everything. Everything needs to be bigger for the SSK-N to go faster. But the fundamental question is, why does your SSK-N need to go fast?

Yes, being able to go fast is good, it unlocks a lot of capabilities and options, but that’s why you want SSNs. If you want more SSNs, just build another SSN production facility. It’s frankly more than a little bizarre for China to have only one SSN/SSBN production base, when redundancy and competition is so prevalent everywhere else, and one on the coast too, making it extra vulnerable. If the desire is for more fast attack subs, the logical solution is to make Wuchang into another SSN/SSBN production base, or create a whole new yard on Hainan island; not mess around with a compromised SSK-N design.

The only reason SSK-N makes sense is from the POV of maximising the benefits of existing industrial production base, experienced crews and fleet support infrastructure. Why tie yourself in knots needlessly trying to make SSK operate like SSNs when SSKs already fulfil a perfectly adequate role in the PLAN’s order of battle?

It would be like going crazy trying to make the J16 into a Silent Flanker with a tiny internal weapons bay but still orders of magnitude bigger RCS than true stealths like the J20 to work like a poor-man’s J20 that is worse in every way. When the PLAAF could just order more J20s if it really wanted more J20s and no more J16s.

SSK’s ambush tactics are perfectly valid on modern naval combat, and their ability to camp key choke points gives the PLAN a lot of operational flexibility and security.

So if you scale back the ambition from making an SSN-M to just making an SSK-N, which can operate as existing SSKs can, only it doesn’t need to surface at all during its entire deployment, then a lot of the unreconcilable size problems simply doesn’t exist in the first place.

 

[tphuang]

I think if you find yourself trying to reconcile two impossible factors, you need to re-examine the assumption that created this impossible position in the first place.

Much of the massive size requirement you are struggling with is rooted in the assumption that the SSK-N needs to go fast. That speed requirement is what is driving the power requirement that requires a massive Stirling engine; and also the larger battery pack; bigger propulsion system, more complex electrical system; drive train and gearing, basically everything. Everything needs to be bigger for the SSK-N to go faster. But the fundamental question is, why does your SSK-N need to go fast?

Yes, being able to go fast is good, it unlocks a lot of capabilities and options, but that’s why you want SSNs. If you want more SSNs, just build another SSN production facility. It’s frankly more than a little bizarre for China to have only one SSN/SSBN production base, when redundancy and competition is so prevalent everywhere else, and one on the coast too, making it extra vulnerable. If the desire is for more fast attack subs, the logical solution is to make Wuchang into another SSN/SSBN production base, or create a whole new yard on Hainan island; not mess around with a compromised SSK-N design.

The only reason SSK-N makes sense is from the POV of maximising the benefits of existing industrial production base, experienced crews and fleet support infrastructure. Why tie yourself in knots needlessly trying to make SSK operate like SSNs when SSKs already fulfil a perfectly adequate role in the PLAN’s order of battle?

It would be like going crazy trying to make the J16 into a Silent Flanker with a tiny internal weapons bay but still orders of magnitude bigger RCS than true stealths like the J20 to work like a poor-man’s J20 that is worse in every way. When the PLAAF could just order more J20s if it really wanted more J20s and no more J16s.

SSK’s ambush tactics are perfectly valid on modern naval combat, and their ability to camp key choke points gives the PLAN a lot of operational flexibility and security.

So if you scale back the ambition from making an SSN-M to just making an SSK-N, which can operate as existing SSKs can, only it doesn’t need to surface at all during its entire deployment, then a lot of the unreconcilable size problems simply doesn’t exist in the first place.

039B transits in periscope depth. diesel subs as a whole need to do a lot of surfacing to not blow through its battery storage.

mini-nuke will transit deep enough that it cannot be detected by aerial SAR or satellites radar. That alone means the power requirement is higher.

Atmospherical control alone would be several hundred kw.

These are all higher requirements.

Why would I operate a mini nuke as a SSK?

SSKs are not useful outside of ambush roles against USN.

 

[Andy1974]

@tphuang why does SSK-N need a diesel backup if it has battery?
A SSK has 2 sources of power, so a SSK-N should also only have 2, the reactor and the battery.