On 30 Oct 2021 at 18:57:36 BST, newshound <newshound@stevejqr.plus.com> wrote:

> On 30/10/2021 15:23, Dimitris Tzortzakakis wrote:
>> Στις 16/9/2021 4:49 μ.μ., ο/η gareth evans έγραψε:
>>> After following the Vigil TV series (with all its
>>> reported errors) and also the prog on HMS Trenchard,
>>> when a Brit U-boat is powered by nuclear fuels, how
>>> do they condense the steam?
>>>
>>> With sea water? If so, there must be difficulties
>>> in sealing the intakes and outfalls from deep sea
>>> pressures.
>>>
>>> Perhaps the steam is heated to 200C and only cools to
>>> 100C through the turbines before recirculating
>>> so no condensing is
>>> required. This, of course, will be wasteful
>>> of some thermodynamic energy, but there's so much
>>> in reserve in the nuclear fual that perhaps it does not
>>> matter.
>>>
>> 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.
>
> 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.

I thought the sequence was:

1) Brazed joint fails allowing ingress of sea-water while they were at test
depth.

2) Sea water shorts some circuits leading to reactor scram

3) Attempts to blow tanks fail because expanding air cools so much that
moisture within it freezes and jams the valves, preventing blowing of tanks

4) Lack of reactor power prevents boat being driven towards surface using
engines, boat sinks instead

--
When it becomes serious, you have to lie.

Jean-Claude Juncker, Reuters 31st May 2013.

On 30/10/2021 19:11, Tim Streater wrote:
> On 30 Oct 2021 at 18:57:36 BST, newshound <newshound@stevejqr.plus.com> wrote:
>
>> On 30/10/2021 15:23, Dimitris Tzortzakakis wrote:
>>> Στις 16/9/2021 4:49 μ.μ., ο/η gareth evans έγραψε:
>>>> After following the Vigil TV series (with all its
>>>> reported errors) and also the prog on HMS Trenchard,
>>>> when a Brit U-boat is powered by nuclear fuels, how
>>>> do they condense the steam?
>>>>
>>>> With sea water? If so, there must be difficulties
>>>> in sealing the intakes and outfalls from deep sea
>>>> pressures.
>>>>
>>>> Perhaps the steam is heated to 200C and only cools to
>>>> 100C through the turbines before recirculating
>>>> so no condensing is
>>>> required. This, of course, will be wasteful
>>>> of some thermodynamic energy, but there's so much
>>>> in reserve in the nuclear fual that perhaps it does not
>>>> matter.
>>>>
>>> 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.
>>
>> 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.
>
> I thought the sequence was:
>
> 1) Brazed joint fails allowing ingress of sea-water while they were at test
> depth.
>
> 2) Sea water shorts some circuits leading to reactor scram
>
> 3) Attempts to blow tanks fail because expanding air cools so much that
> moisture within it freezes and jams the valves, preventing blowing of tanks
>
> 4) Lack of reactor power prevents boat being driven towards surface using
> engines, boat sinks instead
>
>
Yes, that was the official theory. I believe another error was that
there were still debris strainers in the air lines that should have been
removed after commissioning, and that these contributed to the blockage
by ice crystals. I think it is more likely to have been pipe blockage
than valve jamming, you would only get crystals once the valves were
open and the air was flowing.