OT Nuclear U-Boats; how do they condense the steam?

On 20/09/2021 10:59, Pancho wrote:


Bollocks
You may THINK you will get most of the silos, you KNOW you wont get any of the subs
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On 20/09/2021 19:02, The Natural Philosopher wrote:

I don't see why you would say that. Subs can be tracked. The idea that a technology/technique will emerge that can be used to effectively locate all submarines is not that fanciful.
Audio. A network of listening devices. Some other property, I don't know what it is, but with advances in technology I wouldn't rule it out.
The problem is similar to computer security, if you give an opponent a clear attack vector they can hone their techniques.
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Because its true. Novel concept I realise.

No they cant when out in the open ocean. That?s the whole point of them.

Fraid so.

Not feasible over the entire oceans and no way to be sure it?s a sub with nukes in it either. Easy to fake audio signatures.

Clearly not there now.

Nope, nothing like that.

How odd that no one has done that with nuke missile subs.
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On 21/09/2021 10:30, Rod Speed wrote:

Of course they can. They can be followed from base.
[snip]

How would you know if they had done it?
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Nope, no way to do that. All you know is that they have left the base.

The operation that can do that would stop building any more of them.
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On 21/09/2021 09:21, Pancho wrote:

If it were that easy we wouldnyt bother with subs at all.

Its been done. In fact I worked on it back in the 1970s. rubber coated hulls, very slow propellors, down deep. Totally undetectable.
Same goes for thermal signature. You cant 'see' it through a lot of layers of water . And teh sub can run on batteries even if its a nuke,

I can assure you, they do, but I can also assure you, that a sub sitting at depth with engines off is almost impossible to detect. And there are limits to how much of the sea you can litter with sonobuoys.

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Yep.

You're wrong. There is no way to work out where a sub with nukes is once its out in the open ocean submerged and they can stay that way for very long times with nuke powered subs.

Yes, but that is still one hell of a deterrent because that one sub is plenty to ensure that only the most stupid would try nuking the UK.

Doesn?t matter what they say, they aren't for a first strike.

Which are much easier to work out where they are than nuke subs.

Much easier to find those than a nuke sub.

Trivial to keep a list of those and take those out.

But far more likely to be useless.

That?s bullshit. Even Trump wouldn?t be that stupid and the US military wouldn?t do it even if he was stupid enough to order one.
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On 17/09/2021 11:33, Steve Walker wrote: ...

One of which had to jettison its reactor after what is thought to have been a partial meltdown. At it was a Soviet vessel, details are not available.
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Not really if there is no chance that anyone will be silly enough to nuke your country.
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Nope, and we have just stupidly decided to have a fleet of new nuclear submarines and have told the frogs to take theirs and shove them where the sun don?t shine.
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On 16/09/2021 18:17, Scott wrote:

or adopt WW2 acoustic mine sweeping technology by fitting a Kango vibrating hammer to the hull of the ship ;)
From https://www.vernonlink.uk/wwii
" In late October the recovery and exploitation of an acoustic mine ? found ashore in the mouth of the River Ogmore near Porthcawl - allowed a more effective sweep to be developed. This was the Kango vibrating hammer ? known as the ?SA? (Sweep Acoustic) that was being widely fitted before the end of the year and was to see significant success fitted either in the bows of a vessel or streamed outboard. The risks remained significant though; the minesweeping trawler RADNOR CASTLE had to be beached off Plymouth following a too-close detonation and in December HM Trawler COURTIER detonated 4 acoustics in swift succession, the last one breaking the legs of 4 crew members and putting the trawler in dock for several months. A less conventional minesweeper also incurred damage in late December 1940; the fast Isle of Man Steam Packet SS VICTORIA had already set off 8 or 9 mines during her transits back and forth to Liverpool, but on the 27th the detonation just off the Douglas Bar Light was a little too close and she had to be towed back to port although, in this instance, no casualties were reported. "
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Rather unlikely any spy or spy ship bothers to monitor each one leaving port in the hope that there might be a mistake.
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On 16/09/2021 18:10, GB wrote:

...

I would be most surprised if a nuclear sub put to sea relying on the memory of the crew, rather than on comprehensive check lists, to ensure that everything is done right.
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Colin Bignell

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On 16/09/2021 15:54, nightjar wrote:

I'm guessing these will be conceptually similar to those used by conventional power plant, which has an array of tubes about 3 inches in diameter (with similar spacing) through which the seawater passes. In the old days these would have been a copper alloy (good for anti-fouling), now I expect they will be titanium for better corrosion resistance.

1000 feet is about 30 bar / 450 psi, a relatively modest figure for unfired pressure vessels. Obviously, the tube-plates have to be properly designed.

The steam temperature in a commercial PWR is a bit over 300 deg C and I expect the submarine figure is comparable. They will probably be aiming for a condenser temperature around 30 deg C, giving a pretty good vacuum (about 30 torr). A surprising proportion of the energy in a steam turbine is delivered by the Low Pressure rotor(s).
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On Thu, 16 Sep 2021 21:11:38 +0100, newshound

I wonder how they deal with the thermal signature of that much heat being released back into the sea?
It almost makes me wonder if they are not making more of an effort to scavenge that energy, not because they need it but just because they don't want to leave a heat trail.
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On 16/09/2021 21:11, newshound wrote:

With nuclear power, given that they are practically fuelled for life, there is no especial demand for efficiency. There is a demand for compactness however. They may not have a low pressure rotor!
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I would have thought that using sea water would be very difficult, due to the corrosion it might create in the heat exchanger, or whatever they use to cool the water. Besides, if heat from water changed as the sub moved, surely it would be detectable quit easily by the other side. There have been some terrible depictions of nuclear reactors in films and TV shows over the years. The one in The world is not Enough is pretty stupid in my view. I cannot see it of course but the audio describer explained the end scene and he sounded almost embarrassed at the situation.
I would have thought that many reactors these days that needed to be small may well use some other material to get the heat away to do the work. Sodium perhaps, though let that come in contact with water and you have a very bad day. Brian
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On 17/09/2021 08:28, Brian Gaff (Sofa) wrote:

Two points. You have to dump "low temperature" heat somewhere to have a thermodynamic cycle from which you extract energy. In a sub, the only place is the sea.
IIRC the Soviets have used fast reactors in subs, I think with lead or lead/bismuth cooling rather than sodium. I think everyone else uses pressurised water reactors.
While mixing sodium and water is bad news, the death knell for the Dounreay Prototype Fast Reactor was corrosion, more accurately stress corrosion cracking, on the *water* side of the sodium to water heat exchanger where the steam is raised. This is hot, very pure water which poses more materials challenges than the the cold seawater-to-steam condenser.
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???? 16/9/2021 4:49 ?.?., ?/? gareth evans ??????:

well, the expected answer is with sea water, the same "coolant" that convential ships use. I read once a german article about the sinking of the US submarine "Thresher", that was designed to go deeper thna usual, and that was not combined with welding of its pipes, instead of soldering, to withstand the higher pressures involved, also they needed a "clean room" to work, so it's possible that a speck of dust sank the 300 m submarine! Also that it needed a more powerful air compression system, so it could "blow" its ballast tanks in distress, especially following a reactor SCRAM.
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On 30/10/2021 15:23, Dimitris Tzortzakakis wrote:

Two theories, one official and one unofficial, are very well described here.
https://en.wikipedia.org/wiki/USS_Thresher_ (SSN-593)
It is true that the Thresher had brazed heat exchangers, which showed faults in subsequent boats. I don't see any justification for the "speck of dust" claim and I don't think the Thresher was particularly designed for deeper diving, although this aspect of performance is normally classified. It has been surmised that they were unable to "blow" the tanks because of ice crystals blocking the lines.
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