Yuan Class AIP & Kilo Submarine Thread

[tacoburger]

In addition to what FairAndUnbiased said, the moment you introduce nuclear into the equation, your costs goes up multifold, so it doesn't make sense to have a nuclear power unit 10% the power of a classical SSN and expect to only have 10% of the purchase and 10% of the maintenance costs. Your 1-2 MW reactor will still require you to have highly skilled nuclear power engineers on the crew, nuclear fuel cycle procedures, radiation shielding, reactor management systems, isotopic gas and fusion byproduct management systems, etc. By that point you might as well go full SSN due to the sunk costs. This is also why small localized nuclear power plants have not taken off for land based utility power generation.

I think it might depend on how tech evolves. A thermal power plant running a coal fired steam turbine and a car are both fossil fuel fired, but the car is operable by 1 person while the coal fired steam turbine needs a team of full time engineers and technicians to keep running.

There are some modular reactors like pebble bed gas cooled types that are simpler, safer and less prone to failure than water cooled types, but have had limitations on maximum power generation relative to water cooled ones when staff is available.

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They might use an upscaled version of this. Extremely safe, designed for deep space missions lasting decades with no maintenance. There's also plenty of mirco nuclear reactor designs floating around that require very maintenance and are designed to be mass produced to lower cost. Small too, they can be fitted to the back of a truck.

Size shouldn't be a issue. Switching from lead acid to lithium ion probably already provides a vast improvement in space, with lithium ion having around twice the volume and mass energy density. If you have a constant 1MW electrical output, you can further cut your battery size and diesel storage by a lot too.

Of course, all this changes and you might as well just design a new submarine from the ground up.

 

[BoraTas]

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They might use an upscaled version of this. Extremely safe, designed for deep space missions lasting decades with no maintenance. There's also plenty of mirco nuclear reactor designs floating around that require very maintenance and are designed to be mass produced to lower cost. Small too, they can be fitted to the back of a truck.

Size shouldn't be a issue. Switching from lead acid to lithium ion probably already provides a vast improvement in space, with lithium ion having around twice the volume and mass energy density. If you have a constant 1MW electrical output, you can further cut your battery size and diesel storage by a lot too.

Of course, all this changes and you might as well just design a new submarine from the ground up.

I looked at the article and as far as I can read there, 50 years of effort resulted in a single 110 Watt design. The tech doesn't sound really promising.

In general, I think SSKs with small nuclear reactors (let's call them SSKN) don't offer much. The point of an SSN is unlimited high-speed submerged endurance. That's their whole point. Thanks to that trait they can pursue and evade adversaries effectively. They can also transit long distances without raising any snorkels and fast. SSKs can't do these. An SSKN might have unlimited low-speed endurance but what's the point? Modern SSKs with AIP can do the same for 3 weeks too. The Spanish S-80 Plus class sub is capable of 30+ days thanks to its size and Methanol reformer. That's enough for pretty much everything unless you are going to hunt US carriers in open ocean.

You will need around 10 MW thermal in an SSKN to achieve a 1 MW shaft output. That would likely result in unlimited endurance at 12 kn or so. The problem is that is a real nuclear reactor that needs all the SSN infrastructure and specialized crews. Better go full SSN at that point.

 

[tacoburger]

I looked at the article and as far as I can read there, 50 years of effort resulted in a single 110 Watt design.

That's because it's meant for deep space missions, where weight and space are at a premium. It's tiny. I don't see why a up scaled versions can't produce more power. There's a bunch of other micro nuclear reactors designs for deep space missions, which are also meant to be extremely long lasting, safe and require basically no maintenance. The biggest design was for a 100 kilowatt version, so it can be scaled up.

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That's enough for pretty much everything unless you are going to hunt US carriers in open ocean.

China might not need this now, but in the decades when she pushes deeper and deeper into the pacific?

You will need around 10 MW thermal in an SSKN to achieve a 1 MW shaft output. That would likely result in unlimited endurance at 12 kn or so. The problem is that is a real nuclear reactor that needs all the SSN infrastructure and specialized crews.

I see the reactor just being used as a supplement to extend the life the batteries. So it's scalable, even a hundred kilowatts can be enough depending on the needs of whatever situation China finds itself in when it's designing this kinds of submarines.

Anyway, I see this as a good jumping off point for developing good mirco-reactor tech. It's possible for a design to be cheap, safe and require very little maintenance, it's just a measure of engineering and economy of scale. You might be right that SSNs are the right call for now, but in 10-20 years? What if unmanned submarines swarms become a thing?

If you don't need food or feel the stress of being clamped in a metal tube for years, then years can be the extend of your mission. If you want a cheap drone swarm that can lurk in the depths of the Pacific or Indian oceans for years on end, or stay in some underwater cave just kilometers away from a major city or port for years, then a tiny cheap and maintenance free mirco-reactor is the way to go, no point in a 200mw reactor for a medium sized drone.

And of course, this tech can be applied everywhere else if developed. Slap 2 10 MW reactors together and put it onto destroyer for infinite range. Use it as a SMR for a village etc etc.

 

[BoraTas]

That's because it's meant for deep space missions, where weight and space are at a premium. It's tiny. I don't see why a up scaled versions can't produce more power. There's a bunch of other micro nuclear reactors designs for deep space missions, which are also meant to be extremely long lasting, safe and require basically no maintenance. The biggest design was for a 100 kilowatt version, so it can be scaled up.

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China might not need this now, but in the decades when she pushes deeper and deeper into the pacific?

I see the reactor just being used as a supplement to extend the life the batteries. So it's scalable, even a hundred kilowatts can be enough depending on the needs of whatever situation China finds itself in when it's designing this kinds of submarines.

Anyway, I see this as a good jumping off point for developing good mirco-reactor tech. It's possible for a design to be cheap, safe and require very little maintenance, it's just a measure of engineering and economy of scale. You might be right that SSNs are the right call for now, but in 10-20 years? What if unmanned submarines swarms become a thing?

If you don't need food or feel the stress of being clamped in a metal tube for years, then years can be the extend of your mission. If you want a cheap drone swarm that can lurk in the depths of the Pacific or Indian oceans for years on end, or stay in some underwater cave just kilometers away from a major city or port for years, then a tiny cheap and maintenance free mirco-reactor is the way to go, no point in a 200mw reactor for a medium sized drone.

And of course, this tech can be applied everywhere else if developed. Slap 2 10 MW reactors together and put it onto destroyer for infinite range. Use it as a SMR for a village etc etc.

I think that's a different topic. Unmanned subs of the future might very well get nuclear reactors. But we need huge improvements in underwater communications and AI to even consider such a CONOPS. Auto underwater operations are at a quite primitive level right now. Cooperation between submerged assets is also quite primitive even for manned vessels. After such a CONOPS becomes viable I am all for small nuclear power generators.

Speaking of the SRG, the tech doesn't sound very scalable. There is such a statement:

"Several viable generator designs in the range of 100-500 Watts have emerged from the ongoing dynamic conversion technology development effort."

 

[by78]

Self-explanatory.

 

[Strangelove]

 

[BoraTas]

Do we know what happened to the new Yuan? We saw more than one ship and a few shipyard statements so it was 99% not a prototype.
If they continued producing it at a rate of 2-3 subs, there should be 6 in the navy already. Any opinions?

 

[Maikeru]

Do we know what happened to the new Yuan? We saw more than one ship and a few shipyard statements so it was 99% not a prototype.
If they continued producing it at a rate of 2-3 subs, there should be 6 in the navy already. Any opinions?

Delayed by Covid? We should have seen at least one of the PN Hangor boats by now but they are delayed.

 

[Tam]

Do we know what happened to the new Yuan? We saw more than one ship and a few shipyard statements so it was 99% not a prototype.
If they continued producing it at a rate of 2-3 subs, there should be 6 in the navy already. Any opinions?

Just about every new picture we now see of the Yuan is a curved sail type. At the same time, pictures of the straight squared sail type had virtually disappeared in later years.

The explanation is simple. As they are building few of the new types each year, the older ones were retrofitted to the same standard as the new ships.

So I may assume that all the current Yuan in service might already be of the curved sail type.

 

[BoraTas]

Just about every new picture we now see of the Yuan is a curved sail type. At the same time, pictures of the straight squared sail type had virtually disappeared in later years.

The explanation is simple. As they are building few of the new types each year, the older ones were retrofitted to the same standard as the new ships.

So I may assume that all the current Yuan in service might already be of the curved sail type.

I meant the new model we saw. One with the distinctive sail and TAS. What about it? We didn't see new boats for a long time.