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Comment by thinkcontext | Hacker News Reader

Maybe a non-event for safety but what about getting the plant operating again?

I don't know this plant. In navy submarine reactors like the S5W, you have 440V/3-phase power holding the clamp. If you dropped a rod due to a power or clamp malfunction, usually you'd simply shut down the reactor, drop all the rods and mechanically re-engage the clamp. It could take a few hours which isn't fun because no power which probably means submarine/snorkel depth to run the incredibly noisy diesel, but no step was particularly hard or dangerous.

Now I’m curious. What if it occurs when you’re like under the enemy and you can’t surface? Do you have to just chill at depth until you can get the reactor running again?

I'd imagine the operational capabilities of nuclear submarines are somewhat confidential.

Warships have a “battle short” on some critical equipment, which will bypass safety equipment like fuses. If your gun turret traversal motors pull too much current in the middle of a battle, you’d rather risk damage or fire to have them keep working rather than disable themselves to protect from a fault. Total speculation here, but it would make sense for military reactors to have something similar, to put them in a mode where the threat of a reactor accident due to a malfunction is less than the threat from the enemy if it goes down. https://en.wikipedia.org/wiki/Battleshort

Likewise commercial aircraft have bypasses on the fuel and oil filters in case they get clogged in flight. The engine will need a thorough inspection if this happens but it's better to damage the engine if it gets you to the nearest airfield.

I’ve never been in the Navy or on a submarine, but my impression is that SUBSAFE is about never ever having a reactor accident, at least partially for PR reasons. It wouldn’t surprise me if there simply are not procedures to deliberately put the reactor in a dangerous state.

The Navy may have done the math and determined the loss of a boat to the enemy is a less bad thing than the loss of a boat to a “nuclear accident”.

I desperately hope for and welcome anyone with experience in the space to correct me.

Wouldn't a nuclear powered ship sunk by enemy fire be a nuclear accident on its own? There would be a nuclear reactor on the seafloor, possibly a turned on one, surrounded by failed systems. I don't think it ever happened at war, but while I was looking for [1] I found a number of other incidents. I list them below

[1] https://en.wikipedia.org/wiki/Kursk_submarine_disaster

[2] https://www.sciencedirect.com/science/article/abs/pii/S00295...

[3] https://en.wikipedia.org/wiki/Soviet_submarine_K-19

[4] https://www.ebsco.com/research-starters/history/soviet-nucle...

[5] https://gizmodo.com/sunken-soviet-submarine-is-quietly-leaki...

[6] https://en.wikipedia.org/wiki/Submarine_incident_off_Kildin_...

[7] https://en.wikipedia.org/wiki/Submarine_incident_off_Kola_Pe...

If you find the story of the Kursk interesting, you should read "Darkness at Dawn" (Satter, 2003)

The nuclear incident in a sub would be less problematic than stealing the nuclear missiles out of the sub. Like a Titan out of the Kursk sub.

They initially didnt have quick restart procedures for that and it contributed to a nuclear sub sinking. After that they added those procedures and improved the technology

https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)#Cause

> After the accident Rickover further reduced plant restart times, which had already been gradually improving with new technology and operating experience, in addition to limiting factors that could cause a shutdown.[26]

The ship can operate for a bit on decay heat. And they have battery banks to run major systems until conditions allow running at snorkel depth on the diesel engine.

And rumor has it some of the nuclear subs may work with a Stirling engine which can operate systems on heat alone.

The small sub world is going toward AIP. I wouldn't be surprised if the big ones have AIP for emergency power.

AIP?

Air-independent propulsion.

Wow, that’s a whole lot of Liquid Oxygen in most of those designs.

Not sure if that is better or worse than massive quantities of high test hydrogen peroxide.

Spicy.

AIP range is still limited though, especially at fast speeds. Thats why even the newest 212CDs still have have snorkels for their diesel and diesels are loud. SSNs are much better for global power projection.

Fine for running electric power for a time though. Which is probably what you'd use it for on a nuclear sub. Assuming you can spare the space/weight in your design.

out of curiosity, where's the heat for a Stirling engine coming from, or what would be the thermodynamic advantage if you were already collecting decay heat from the reactor? People breathing hotly in a tube?

An S5W scram probably has contributed to USS Tresher sinking because they couldn't get it running fast enough again

https://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)#Cause

The final paragraph of the article

> According to NextEra Energy, Unit 1 at St. Lucie is back online at 100% power after operators safely resolved an equipment issue.

I wish the article had said where on earth St Lucie is. Never heard of it

St Lucie: Island in the South of the Caribbean. Source: lunch games https://worldlegame.io https://flagle.org

This St. Lucie is in Florida USA, on the Atlantic coast north of Palm Beach and south of Orlando.

It's a local TV station, the target audience already knows where so the information is superfluous.

And the breadcrumbs at the top of the page give you enough information to find out if you're not in the target audience.

You can look it up.

I also didn't know "St. Lucie". I Googled for "St. Lucie Nuclear Power Plant" to find it.

Almost certainly a better problem to have.

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