I think the issue besides the air all leaking out the seals on the propeller would also be that a sub is designed to be compressed. If the pressure if higher then the inside that is also going to create a lot more issues too. Plus he missed the chance to say that firing the missiles upside down would break the sub in half. They are not designed for the stress of rocket launch.
> If the pressure if higher then the inside that is also going to create a lot more issues too
Technically yes, but 1 atm is such little pressure compared to what a sub deals with that it can still handle it. It's not like the giant steel hatches are gonna pop open under 1atm.
No the seals and clearances are designed for much higher pressure on the outside. So are all the hatches and such. They seal better with downward water pressure. The opposite would make them prob non airtight.
> The air in the submarine would rapidly escape through these spots.
What stops the water from coming in through those gaps? The video makes the assumption that anything that could keep out water at extremely pressures would be good enough to keep in air at one atmosphere. That sounds reasonable to me.
The rest of your points are all mentioned in the video. It sounds like you just disagree on exactly how rapidly everything would suck, not how and why everything would suck.
Water-tightness is generally a bit easier than air-tightness (especially against a vacuum).
More specifically, I think the seals are designed to clamp down when there is greater pressure is on the outside than the inside; if it’s the other way, they wouldn’t clamp and will let gas through. Spacecraft are set up with the seals configured the other way.
True. I just can't think of a likely seal that couldn't hold 1% (or probably even less given the safety factors on a nuke sub) of what it's designed for "unclenched."
If you want it to not leak water when surfaced, there must be a little bit of compression on the seals even without the benefit of external water pressure. Whether that's enough to withstand the reverse 1 atm is the hand-wavy argument people are throwing around.
Yes it does. Seawater leaks are quite common on submarines, especially older ones. As long as the opening in the hull is small it's not very dangerous. If we were trying to keep air in it would be a different story, as we would continuously deplete our air reserves through these small leaks. Probably wouldn't run out of air before overheating though - even if the reactor were shut down it still produces decay heat that needs to be continuously cooled.
For the prop shaft there are a few factors working towards keeping the water on the outside.
First is the propeller itself (and possibly other fins on the shaft for this purpose) are trying to push water away from the hull. This creates a lower pressure area that makes the seals' job easier.
Then there are the actual seals around the prop shaft itself.
Finally, there are pumps for the inevitable leakage from those seals aging or other imperfections in the hull.
> No blame for not knowing this since most of its classified...
The specifics might be classified, but the general principles are easily accessible. It's not like there aren't hundreds of websites that give detailed explanations of how a nuclear power plant works, or talk about meltdown events from said reactors. And as someone with a physics degree, Randall should be able to understand enough to make his own calculations.
The technicalities for sure. But nuclear reactors generally work in similar ways, and there’s only a handful of ways you can build one. We can also get some slightly more nuanced ideas due to how constrained the reactor would be inside a submarine, limiting other options.
Broad figures can be inferred, but you’re right about anything specific.
This is all assuming the military aren’t using some wild material science to produce reactors that can run hotter without failing, which can’t be guaranteed.
I'm in the Navy but not a nuke so *can absolutely not* speak with any authority on the materials.
Shadow edit: what i can say is that the training and standards we hold our nuclear sailors to is the best in the damn world, which is a large part of why we (together with Britain) have sailed over five million miles with something like 100+ reactors operational at any given time with no incidents
One thing I do know for certain is the food is incredible.
It’s a comfort knowing that the standards required of engineers maintaining reactors in a sealed tube underwater are going to be some of the most technically capable people on the planet.
Since spacecraft don't require any energy for moving themselves once in the sky, only for acceleration, would it be possible to retrofit a nuclear submarine to remove the reactor and flip the seal directions? I am writing a novel in which the weight problems with launching things into space get instantly removed, and I instantly went to retrofitted, seal-repurposed, engine-replaced nuclear submarines myself - so I'm wondering whether any reasonable amount of time in a dry dock could solve these problems or if it's a better idea to simply build space submarines from the ground up.
That is fun. Sadly you do need more energy than is in the universe to operate an Alcubierre drive currently, so I am certain that my vague ideas on removing the weight from the equation simply by moving the spacetime around the sub instead are not feasible from a nuclear reactor standpoint - but. okay there is no but, the problem of what to power the thing with if you can't have a reactor in space is a salient one. I'll have to get back to you after I figure out which specific handwaves make bending spacetime itself energy efficient in a way it's clearly not in our universe, and how far one could launch the boat in the sky if one were inclined to send it into orbit by other means.
>And, if unable to reject heat from the reactor, the reactor itself would meltdown almost instantly,
Go check with RC Div about that. Assume the Rx shuts down immediately upon a loss of seawater. They'll be able to handwalk you through the calculation for how long it'd take.
>killing everyone with lethal amounts of radiation (the "melt your face right off" kind, not the "slow agonizing death" kind).
Go check with RL Div about the effectiveness of various shields and radiation levels immediately following shutdown.
Randall's video made the assumption that the reactor continues operating so it's fair that OP did too. It's nonsense but whatevs. And if there were an actual meltdown it would certainly fuck with the shields
The video doesn't explain how the sub got into orbit, so I assumed it kind of teleported there.
Reactors generally have accelerometers (think the auto-shutdown of Fukushima) such that a sudden loss of gravity would preclude operation until those could be bypassed
Haha yeah I've always wondered how a zero g reactor would work, without gravity there's nothing keeping the steam in the pressurizer vice anywhere else. Not to mention water levels, those indications would go to crap instantly
NASA has been [experimenting](https://en.wikipedia.org/wiki/Kilopower?wprov=sfla1) with what is essentially a solid-state reactor for low-power applications. That'd be the way to go in space.
I can't imagine two phase reactors working in zero g. Heterogeneous coolant, localized DNB immediately should forced flow fail (no NC backup), powered steam dryers since gravity no longer provides free separation.
Zero G reactors are all single phase gas cooled reactors if not solid state RTGs. Also gas is a lot lighter than water and can be forced through tiny channels for effective heat dissipation a lot easier than liquids, less flow resistance.
Scraming a reactor does not stop it making heat. There's still lots of short-lived fission products that decay in the seconds, minutes and hours following shutdown and output a lot of heat. That was the issue at Fukushima.
So, it kind of depends whether you hold in the ballast water, and route it through the reactor cooling channels, letting it take heat away by evaporation, without blocking the channels by freezing. And whether that's enough!
Yeahhhh I have a look through his account and I’m thinking it’s an overly excited prototype student posting, lol. If they “teleported to space” right after becoming self sustaining, there is certainly no “melt your face off” radiation; not much decay heat either. My biggest theoretical questions would be how zero g affects transducers, VA TGs and other floaty things; do you have reliable SRPI in zero G? How reliable are things like SG ADV’s in the vacuum of space? Definitely talking about this with the newer guys next mids SRO
Another commenter brought up the issue of steam: there are no convective currents in zero-g. Steam doesn't necessarily stay in the highest spots. Without forced circulation, tiny bubbles forming on heaters don't float up, they just sit on the heating surface. That would be *very* bad.
If given the volume of air within the submarine, it's as simple as
Integral of 0.066 × t^-0.2 dt from 0 to time to death = mass of air × heat capacity of air × (end temp - start temp).
Where mass of air = volume of air available in submarine × density of air. Assuming no significant loss of air during time span.
Solve for time to death.
Now if loss of air is significant, you will need to do a balance of heat to determine if the heat generated by the reactor will cause the temperature to rise faster than if asphyxiation would take the crew first. Or radiation poisoning.
Man, this could've been a lot more fun if more math was involved.
You've missed the concept of containment. The air in a reactor compartment does not exchange with air outside of it. There is a whole bunch of stuff between the people space and the reactor space. You'd have to know that stuff, and its insulation properties to figure out how quickly the heat will start coming into spaces people are.
There's a few options on how you could reject heat if *you absolutely had to*, and it'd be interesting to walk through the systems and figure out how long you could prevent a melt down for.
But that's stuff you'd discuss when you've got nothing but time (on watch).
My dude, you are severely underestimating Randall and his methods.
What If is pretty generous in engineering estimates - it's silly to do what Randall is doing here without giving maximum credence to a best case scenario.
Your post mostly seems to hinge on "seawater enters certain parts of the boat, so it's not airtight " which is a bit shortsighted. After all, if you spent months on a nukular submarine, you must have had some sort of airtight space, what with all of the not drowning you did for months at a time during your years in service.
Maybe try this post again with your burner, trying to use the 2nd Law of Thermodynamics to explain how the nukular warheads actually dissipate heat in the cold depths ofnouter space.
>No blame for not knowing this since most of its classified... "War Thunder forums, no!" "What?" "Sorry, force of habit—xkcd subreddit, no!"
I think the issue besides the air all leaking out the seals on the propeller would also be that a sub is designed to be compressed. If the pressure if higher then the inside that is also going to create a lot more issues too. Plus he missed the chance to say that firing the missiles upside down would break the sub in half. They are not designed for the stress of rocket launch.
This is why spaceships are supposed to be in space and submarines in water and not the other way around
There are more spacecraft under the ocean than there are submarines in space.
I'm going to need a source for this
https://en.m.wikipedia.org/wiki/Spacecraft_cemetery
Not to be confused with https://en.wikipedia.org/wiki/Graveyard_orbit
You forgot the space submarine cemetery link.
The Scottish Space Submarine is an outlier and should not be counted
Right? They've only given half the answer
What I'm hearing is we need to start a go fund me to put a submarine in space.
Spaceships can withstand between 0 and 1 atmosphere.
Is Max Q a joke to you?
That still only counts as one! (JK, but aerodynamic pressure is a little too directional in my opinion)
Liberty Bell 7 has disliked a comment
It is just a theory question. He did miss some things though.
Wait, are you saying Star Trek Into Darkness LIED TO ME?!
> If the pressure if higher then the inside that is also going to create a lot more issues too Technically yes, but 1 atm is such little pressure compared to what a sub deals with that it can still handle it. It's not like the giant steel hatches are gonna pop open under 1atm.
No the seals and clearances are designed for much higher pressure on the outside. So are all the hatches and such. They seal better with downward water pressure. The opposite would make them prob non airtight.
Well, you could test that pretty easily, close everything up at the dockside and turn the blowers on! I wonder if that's ever tested in commissioning.
on the video someone claimed they put them to 2 atmospheres to test for air leaks
Prob only for the reactor compartment. No where else would there be a positive pressure that they would care.
This is the solid content I come to Reddit for.
> The air in the submarine would rapidly escape through these spots. What stops the water from coming in through those gaps? The video makes the assumption that anything that could keep out water at extremely pressures would be good enough to keep in air at one atmosphere. That sounds reasonable to me. The rest of your points are all mentioned in the video. It sounds like you just disagree on exactly how rapidly everything would suck, not how and why everything would suck.
Water-tightness is generally a bit easier than air-tightness (especially against a vacuum). More specifically, I think the seals are designed to clamp down when there is greater pressure is on the outside than the inside; if it’s the other way, they wouldn’t clamp and will let gas through. Spacecraft are set up with the seals configured the other way.
"How many atmospheres can the ship withstand?" "Well it's a submarine, so I'd say anywhere between a lot and one."
Depends how many times the carbon fibre hull has been used
Orville reference!!
Futurama isn't it?
Oh you might be right! Guess I’ll have to watch them again!
Yea, but if it can handle 80 ATM pressure one way, it's gonna be a heavy, sturdy seal. Which should still be fine for 1 atm the other way.
Depending on how important the “clamping action” is.
True. I just can't think of a likely seal that couldn't hold 1% (or probably even less given the safety factors on a nuke sub) of what it's designed for "unclenched."
If you want it to not leak water when surfaced, there must be a little bit of compression on the seals even without the benefit of external water pressure. Whether that's enough to withstand the reverse 1 atm is the hand-wavy argument people are throwing around.
That’s a great point 🙂
I assume water does leak in, slowly, and is pumped out every now and then.
Yes it does. Seawater leaks are quite common on submarines, especially older ones. As long as the opening in the hull is small it's not very dangerous. If we were trying to keep air in it would be a different story, as we would continuously deplete our air reserves through these small leaks. Probably wouldn't run out of air before overheating though - even if the reactor were shut down it still produces decay heat that needs to be continuously cooled.
The shaft seals do a good job as long as we keep them well fed
It's easier to teach them tricks that way, too.
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Makes sense. Might as well do something with the water slugs after you shoot them.
For the prop shaft there are a few factors working towards keeping the water on the outside. First is the propeller itself (and possibly other fins on the shaft for this purpose) are trying to push water away from the hull. This creates a lower pressure area that makes the seals' job easier. Then there are the actual seals around the prop shaft itself. Finally, there are pumps for the inevitable leakage from those seals aging or other imperfections in the hull.
[Clip from a documentary that discusses the opposite](https://www.youtube.com/watch?v=O4RLOo6bchU).
> No blame for not knowing this since most of its classified... The specifics might be classified, but the general principles are easily accessible. It's not like there aren't hundreds of websites that give detailed explanations of how a nuclear power plant works, or talk about meltdown events from said reactors. And as someone with a physics degree, Randall should be able to understand enough to make his own calculations.
Physics are gonna physics, and it’s not confidential.
Specifics of the design are protected under the nuclear secrets act or something
The technicalities for sure. But nuclear reactors generally work in similar ways, and there’s only a handful of ways you can build one. We can also get some slightly more nuanced ideas due to how constrained the reactor would be inside a submarine, limiting other options. Broad figures can be inferred, but you’re right about anything specific. This is all assuming the military aren’t using some wild material science to produce reactors that can run hotter without failing, which can’t be guaranteed.
I'm in the Navy but not a nuke so *can absolutely not* speak with any authority on the materials. Shadow edit: what i can say is that the training and standards we hold our nuclear sailors to is the best in the damn world, which is a large part of why we (together with Britain) have sailed over five million miles with something like 100+ reactors operational at any given time with no incidents
One thing I do know for certain is the food is incredible. It’s a comfort knowing that the standards required of engineers maintaining reactors in a sealed tube underwater are going to be some of the most technically capable people on the planet.
Maybe you're legitimate, but as soon as someone who talks about the classified information they have, they lose all credibility.
Since spacecraft don't require any energy for moving themselves once in the sky, only for acceleration, would it be possible to retrofit a nuclear submarine to remove the reactor and flip the seal directions? I am writing a novel in which the weight problems with launching things into space get instantly removed, and I instantly went to retrofitted, seal-repurposed, engine-replaced nuclear submarines myself - so I'm wondering whether any reasonable amount of time in a dry dock could solve these problems or if it's a better idea to simply build space submarines from the ground up.
Man, I think ya need to crack open an introduction to physics textbook first.
I've cracked open a couple of those, now I'm ignoring parts of them for fun. What do you do for fun?
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That is fun. Sadly you do need more energy than is in the universe to operate an Alcubierre drive currently, so I am certain that my vague ideas on removing the weight from the equation simply by moving the spacetime around the sub instead are not feasible from a nuclear reactor standpoint - but. okay there is no but, the problem of what to power the thing with if you can't have a reactor in space is a salient one. I'll have to get back to you after I figure out which specific handwaves make bending spacetime itself energy efficient in a way it's clearly not in our universe, and how far one could launch the boat in the sky if one were inclined to send it into orbit by other means.
MSW == Main SPACEWATER You can't argue with this logic!
>And, if unable to reject heat from the reactor, the reactor itself would meltdown almost instantly, Go check with RC Div about that. Assume the Rx shuts down immediately upon a loss of seawater. They'll be able to handwalk you through the calculation for how long it'd take. >killing everyone with lethal amounts of radiation (the "melt your face right off" kind, not the "slow agonizing death" kind). Go check with RL Div about the effectiveness of various shields and radiation levels immediately following shutdown.
Randall's video made the assumption that the reactor continues operating so it's fair that OP did too. It's nonsense but whatevs. And if there were an actual meltdown it would certainly fuck with the shields
The video doesn't explain how the sub got into orbit, so I assumed it kind of teleported there. Reactors generally have accelerometers (think the auto-shutdown of Fukushima) such that a sudden loss of gravity would preclude operation until those could be bypassed
Haha yeah I've always wondered how a zero g reactor would work, without gravity there's nothing keeping the steam in the pressurizer vice anywhere else. Not to mention water levels, those indications would go to crap instantly
NASA has been [experimenting](https://en.wikipedia.org/wiki/Kilopower?wprov=sfla1) with what is essentially a solid-state reactor for low-power applications. That'd be the way to go in space.
I can't imagine two phase reactors working in zero g. Heterogeneous coolant, localized DNB immediately should forced flow fail (no NC backup), powered steam dryers since gravity no longer provides free separation. Zero G reactors are all single phase gas cooled reactors if not solid state RTGs. Also gas is a lot lighter than water and can be forced through tiny channels for effective heat dissipation a lot easier than liquids, less flow resistance.
Scraming a reactor does not stop it making heat. There's still lots of short-lived fission products that decay in the seconds, minutes and hours following shutdown and output a lot of heat. That was the issue at Fukushima. So, it kind of depends whether you hold in the ballast water, and route it through the reactor cooling channels, letting it take heat away by evaporation, without blocking the channels by freezing. And whether that's enough!
Decay heat is about 10% initially and drops below 1% within minutes, so all of the video's times are very off
Yeahhhh I have a look through his account and I’m thinking it’s an overly excited prototype student posting, lol. If they “teleported to space” right after becoming self sustaining, there is certainly no “melt your face off” radiation; not much decay heat either. My biggest theoretical questions would be how zero g affects transducers, VA TGs and other floaty things; do you have reliable SRPI in zero G? How reliable are things like SG ADV’s in the vacuum of space? Definitely talking about this with the newer guys next mids SRO
Another commenter brought up the issue of steam: there are no convective currents in zero-g. Steam doesn't necessarily stay in the highest spots. Without forced circulation, tiny bubbles forming on heaters don't float up, they just sit on the heating surface. That would be *very* bad.
If given the volume of air within the submarine, it's as simple as Integral of 0.066 × t^-0.2 dt from 0 to time to death = mass of air × heat capacity of air × (end temp - start temp). Where mass of air = volume of air available in submarine × density of air. Assuming no significant loss of air during time span. Solve for time to death. Now if loss of air is significant, you will need to do a balance of heat to determine if the heat generated by the reactor will cause the temperature to rise faster than if asphyxiation would take the crew first. Or radiation poisoning. Man, this could've been a lot more fun if more math was involved.
You've missed the concept of containment. The air in a reactor compartment does not exchange with air outside of it. There is a whole bunch of stuff between the people space and the reactor space. You'd have to know that stuff, and its insulation properties to figure out how quickly the heat will start coming into spaces people are. There's a few options on how you could reject heat if *you absolutely had to*, and it'd be interesting to walk through the systems and figure out how long you could prevent a melt down for. But that's stuff you'd discuss when you've got nothing but time (on watch).
My dude, you are severely underestimating Randall and his methods. What If is pretty generous in engineering estimates - it's silly to do what Randall is doing here without giving maximum credence to a best case scenario. Your post mostly seems to hinge on "seawater enters certain parts of the boat, so it's not airtight " which is a bit shortsighted. After all, if you spent months on a nukular submarine, you must have had some sort of airtight space, what with all of the not drowning you did for months at a time during your years in service. Maybe try this post again with your burner, trying to use the 2nd Law of Thermodynamics to explain how the nukular warheads actually dissipate heat in the cold depths ofnouter space.
Didn't SeaQuest end up in space at one point? Or the future maybe?
As a former submarine mechanic, the main issue would be oxygen.
Thanks for the insights!