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blindsight said:

Small subs with SMRs will still be more expensive than conventional subs, however, their tactical value is comparable and they're still a lot cheaper than traditional SSNs, right?

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gelgoog said:

@blindsight
I know there is a lot of investment into these kinds of naval reactors. For example Russia with the Poseidon. But I doubt they will be used to replace diesels. They are much more expensive. Other countries which used to have small nuclear attack submarines like France with the Rubis class are switching to larger submarines. I do not think they are that viable to be honest. Too small to be effective for the cost they have.

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Xsizor said:

We don't know how exactly US nuke sub collided in SCS but a huge disaster was averted anyway.

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gelgoog said:

You have to take the cost to develop the reactor type into consideration. That alone might run into the billions and take up to a decade. I think that is part of the reason why modern NATO submarines (at least French and UK ones) use the same reactor core for the attack submarines and the strategic ones. Russia also seems to have gone in this direction with most submarines using some variant of the OK-650 reactor be it the Oscar, the Akula, the Yasen, or the Borei.

Because the reactor has moving elements, like pumps, it will be noisier than the batteries. You can use natural circulation in more modern reactors which is a lot quieter but I doubt this works at anything but slow silent running mode. You probably need to engage the pumps to max the reactor output to speed up.

So you would need to spend like a decade designing a reactor at the cost of a billion or more, then you would be producing submarines which might cost close to a billion each. Like half the cost of a large conventional nuclear attack submarine. Because of cramped conditions in submarine it wouldn't be fit for long range patrols like the large ones. Also for that price you likely can buy three conventional submarines and all you need are some batteries and a diesel engine all of which is off the shelf technology.

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AndrewS said:

I recall that the Seawolf is supposed to still be near silent at 19 knots.

That implies that the reactor can still use natural circulation at that speed

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5unrise said:

It's hard to say. This may equally have something to do with the pump-jet propeller on the Seawolf, which eliminates the cavitation associated with traditional bladed propellers.

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gelgoog said:

You have to take the cost to develop the reactor type into consideration. That alone might run into the billions and take up to a decade. I think that is part of the reason why modern NATO submarines (at least French and UK ones) use the same reactor core for the attack submarines and the strategic ones. Russia also seems to have gone in this direction with most submarines using some variant of the OK-650 reactor be it the Oscar, the Akula, the Yasen, or the Borei.

Because the reactor has moving elements, like pumps, it will be noisier than the batteries. You can use natural circulation in more modern reactors which is a lot quieter but I doubt this works at anything but slow silent running mode. You probably need to engage the pumps to max the reactor output to speed up.

So you would need to spend like a decade designing a reactor at the cost of a billion or more, then you would be producing submarines which might cost close to a billion each. Like half the cost of a large conventional nuclear attack submarine. Because of cramped conditions in submarine it wouldn't be fit for long range patrols like the large ones. Also for that price you likely can buy three conventional submarines and all you need are some batteries and a diesel engine all of which is off the shelf technology.

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blindsight said:

China has already put a lot money into this area. And from what I read, this is a new concept, not really a conventional sub, but not like a traditional SSN either. The SMR is a natural circulation one. It's not very powerful but good enough for a sustained underwater speed of about 10 knots. Whenever they need to sprint, Li-ion battery packs will help. So, they don't need a diesel at all. The SMR is designed in a way that they can refuel it easily every 10 years.

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