8 ms·

For fun, consider the question of how you'd "black start" from a loss of all AC power on a submerged nuclear submarine? :)

by mpyne 14y ago

brk 14y ago
"Carefully".
ultimoo 14y ago
I'm certain nuclear power submarines have two nuclear generators always running to prevent this from happening. I also think they may have a diesel powered generator for bootstrapping.
- joezydeco 14y ago
  That was the most interesting part of this article. Even the largest power plant comes down to a simple 12V battery needed to bootstrap the first generator.
  - CamperBob2 14y ago
    Similarly, it's fun to realize that the entire 27-km Large Hadron Collider "runs" on a small bottle of hydrogen that you could hold in your hand. http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg Without that insignificant-looking bottle the whole machine would have nothing to do. (Edit: I do have to wonder how wise it is to paint a bottle of hydrogen to look like a fire extinguisher.)
    - jrabone 14y ago
      Gas bottle colour codes and fire extinguisher colour codes are two distinct namespaces... Here's a handy chart: http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%20Chart.pdf http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%2...
      - CamperBob2 14y ago
        Wow, human factors=massive fail with that chart. "Hmm, is this acetylene or nitrogen?" That's not even getting into the whole red-green color blindness issue that could lead to confusing 'Flammable' with 'Inert' contents.
        jrabone 14y ago
        You can't confuse acetylene or nitrogen, old or new style; acetylene uses maroon for the whole bottle, nitrogen uses black for the shoulder only. Also the cylinders are quite different shapes. Also the colours are for "the room is on fire, quick what's in that gas bottle over there?" situations. Are you allowed to be a safety responder if you're colour blind? For everyone else the rule is pretty simple; GTFO, and if acetylene is involved, GTFO out of the postcode.
        CamperBob2 14y ago
        Still, you don't go out of your way to pick confusing colors. This is Usability 101 stuff. If the room's on fire and I'm in it, I'm a 'safety responder' whether I want to be or not.
    - wnight 14y ago
      Video games have taught us that fire extinguishers blow up so it cancels out.
- Nrsolis 14y ago
  You're certain??? Better check your sources.
- mpyne 14y ago
  Only 1 U.S. submarine has ever had 2 nuclear reactors (bonus points for those who know why it was designed with 2). Soviet submarines often had 2 though. For the U.S. submarines they frequently would test shutting down the 1 operational reactor at-sea and trying to recover from the casualty, just to prove that it could be done when you didn't have time to pre-plan. Edit: U.S. subs do have diesels though. So next question: how do you bring up the diesel engine and its required auxiliaries without AC?
  - Nrsolis 14y ago
    Nice try, Ivan. Remember, it's called the silent service for a reason. Those who know, don't tell; those who tell, don't know.
  - joshAg 14y ago
    With a storeable dc power source, just like a car or truck. I suppose if that failed or had somehow discharged incorrectly, there should probably be a way to handcrank the diesel generator, like how early cars required hand cranking to start. PS: I had to look it up, but that's an interesting reason why that us sub had 2 nuclear reactors.
  - angersock 14y ago
    Never been in the navy, so just guessing. Just kicking around ideas... Option A: You hand-crank the beast somehow? To get the glow-plug going, you again use a hand generator? Hopefully enough to bootstrap the generator (maybe it's a smaller generator that runs a larger one)? Generators all the way down? Option B: You blow ballast somehow and use the inrushing water to drive a turbine that runs the generator or gets it going? Option C: You manually pull the control rods and switch the coolant loop to run a small turbine to prime the generator? Option D: You mayday and get a jump from the Russian/Chinese/Iranian sub following you around? Option E: You try something dumb and dangerous with hydrogen peroxide from the torpedoes (I think/hope that that's phased out now)?
    - glurgh 14y ago
      I think it's mostly batteries, a sub operating at constant depth and in motion is negatively buoyant. If something goes wrong and it loses propulsion, power has to be available immediately to operate the systems that can handle the emergency - whether it's blowing ballast or restarting the reactor. This is a somewhat different constraint than the procedure described by the other reply - ships float without power, subs, not always. I mentioned this upthread - USS Thresher[1] seems to have suffered a loss of both propulsion and ballast control while near test-depth with, unfortunately, tragic results for the vessel and all on board. [1] http://en.wikipedia.org/wiki/USS_Thresher_(SSN-593) http://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)
joshAg 14y ago
I can think of a few possible answers: 1) wouldn't you just insert/remove control rods as needed to restart the nuclear chain reaction? i'm pretty sure most reactors design control rods to be manually insertable/removable, even if there are other way to insert/remove them 2) a standby diesel generator with good ventilation, especially passive ventilation? 3) a large dc power source (ie big, charged batteries) to "jumpstart" either a diesel generator or the nuclear reactor the way my car battery jumpstarts my car when I turn the key 4) some other form of stored potential energy and a generator that can extract it (eg: compressed gas through a turbine) to start 1 or 2. 5) (really just a subsection of 4) human powered generator of some kind. perhaps a few stationary bikes?
- arethuza 14y ago
  Your mention of manual removal of control rods reminded me of the SL-1 reactor accident - where some unfortunate chap went to raise a control rod a few inches but accidentally pulled it out 26 inches - the resulting huge power surge and water hammer caused a very nasty accident killing all 3 operators: http://en.wikipedia.org/wiki/SL-1 http://en.wikipedia.org/wiki/SL-1
- VLM 14y ago
  #1 actually no, a lot of designs have a spring pulling the rod into the core, and an electromagnet sticking to the rod, so if the plant utterly loses power the rod snaps back into the core and can't be pulled out. In theory you could attach the rods to bypass the safety feature but its just not happening. Another issue is you run the coolant pumps to dump a couple MW into the system to reach operating temp/pressure after a day or so, THEN light off the reaction so you don't have varying steam conditions affecting the nuke physics. You don't "heat up" a nuke under nuke power as most assume. Its already thermally hot operating temp when you pull the rods.
  - joshAg 14y ago
    so if i'm understanding correctly, from a black start it would take at least a day for the nuclear reactor to come online? then you'd need at least a couple diesel generators and fuel or power cells to get the reactor into a state where it could start generating power. Since you said megawatts, there will probably need to be a smaller generator or two to start the generators that will start the reactor, since i think MW diesel generators take a fair amount of work to get started themselves. And we haven't even talked about backup generators in separate parts of the boat/ship in case of engine fire/damage. Also, there would probably need to be at least another generator/power cell whose only job is to ensure that the sub can blow its ballast at any time (and of course, just regulate it) that comes up as soon as the reactor goes down.
glurgh 14y ago
Big ole batteries - you'd need them anyway to run systems in the first place, should the reactor be shut down at depth. It looks like something like, say, a Los Angeles class sub can actually run its generator from batteries "[...]power can be provided from the submarine's battery through the Ship Service Motor Generators (SSMGs)." This is a problem that the engineers designing nuclear submarines have thought long and hard about - the USS Thresher and all crew were lost in part due to inability to rapidly restart a scrammed reactor.
- mpyne 14y ago
  Congrats, great answer. Everything I learned on the boat just taught me that I have so much to learn. So many minor details that a ship designer thought up went into each successive class of U.S. submarine. There were many days when I'm surprised again that we haven't lost more submarines due to design flaws or misfeatures.
  - glurgh 14y ago
    Hah, that is surely one of the many differences between reading about a sub and serving on one. Me: US navy nuclear submarines are a much-cited example of the successful design, development and deployment of high-reliability systems. You: I sometimes wonder how it is that more of us are not sleeping with the fishes. Still, everyone from designers to crews must be doing something right since it's apparently possible to drive such a machine into a rock at flank speed[1] or through a boat[2] or have it commanded by someone exhibiting strikingly poor judgement[3]. Without killing everyone on board and better yet, the planet. [1] http://en.wikipedia.org/wiki/USS_San_Francisco_(SSN-711)#Collision_with_seamount http://en.wikipedia.org/wiki/USS_San_Francisco_(SSN-711)#Col... [2] http://en.wikipedia.org/wiki/USS_Greeneville_(SSN-772)#The_Ehime_Maru_incident http://en.wikipedia.org/wiki/USS_Greeneville_(SSN-772)#The_E... [3] http://www.huffingtonpost.com/2013/04/12/michael-ward-affair_n_3071602.html http://www.huffingtonpost.com/2013/04/12/michael-ward-affair...
hudibras 14y ago
Finally, a HN thread that I can contribute to and I'm 9 hours late to the party. I was serving in the engineering department on a USN aircraft carrier (non-nuclear) when a cascading casualty led to all boilers going off line. The ship had an emergency diesel generator aligned to automatically power up, but it failed to start due to a previously-unknown problem. So an 80,000 ton warship with 5,000 people on board slowly drifted to a stop, completely dark except for emergency 60's-era-battle lanterns that were already starting to dim. No steam = no electricity (the normal ship's generators were steam-powered) and no electricity = no steam (because the start-up feedwater pumps and air blowers for the boilers were electric). One of the other two EDGs was already down with a casualty which left a single diesel generator that had to be started with compressed air stored in two huge bottles--so basically had two chances to get the ship moving again. (No electricity = no air compressors to refill the bottles.) After a few hours of double- and triple-checking the alignment of the diesels, electrical systems, and boilers (the original steam plant casualty had to be diagnosed) using flashlights in temperatures well into the triple digits (no electricity = no air condi...you get the idea) we successfully started the one remaining diesel which provided AC to the boilers to start up. By far the scariest day I ever had in the navy. Only saving grace was that we weren't flying planes at the time.
- scrumper 14y ago
  Interesting story, thanks for sharing. Glad I'm reading about it and not living it. I don't know much about this sort of thing, so I'll ask the obvious dumb question: why no batteries to start the diesel generator? Was it too big? Edit: Reading on, it seems like compressed air is the norm. Is it more space efficient than a battery big enough to start a large generator?
  - hudibras 14y ago
    I think it was because the system was simpler and more reliable with no moving parts besides valves, just a giant air bottle with pipes leading to each of the cylinders. No motor to worry about or lead-acid batteries to maintain. The whole system probably took up way more room than a starter motor would but excessive space or weight is not a big concern on an aircraft carrier.

For fun, consider the question of how you'd "black start" from a loss of all AC power on a submerged nuclear submarine? :)

by mpyne 14y ago

For fun, consider the question of how you'd "black start" from a loss of all AC power on a submerged nuclear submarine? :)

brk 14y ago

"Carefully".

ultimoo 14y ago

I'm certain nuclear power submarines have two nuclear generators always running to prevent this from happening. I also think they may have a diesel powered generator for bootstrapping.

joezydeco 14y ago
That was the most interesting part of this article. Even the largest power plant comes down to a simple 12V battery needed to bootstrap the first generator.
- CamperBob2 14y ago
  Similarly, it's fun to realize that the entire 27-km Large Hadron Collider "runs" on a small bottle of hydrogen that you could hold in your hand. http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg http://void.printf.net/~conor/sa/LHCb/LHCfuel.jpg Without that insignificant-looking bottle the whole machine would have nothing to do. (Edit: I do have to wonder how wise it is to paint a bottle of hydrogen to look like a fire extinguisher.)
  - jrabone 14y ago
    Gas bottle colour codes and fire extinguisher colour codes are two distinct namespaces... Here's a handy chart: http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%20Chart.pdf http://www.ior.org.uk/ior_/images/pdf/se/New%20Colour%20ID%2...
    - CamperBob2 14y ago
      Wow, human factors=massive fail with that chart. "Hmm, is this acetylene or nitrogen?" That's not even getting into the whole red-green color blindness issue that could lead to confusing 'Flammable' with 'Inert' contents.
      - jrabone 14y ago
        You can't confuse acetylene or nitrogen, old or new style; acetylene uses maroon for the whole bottle, nitrogen uses black for the shoulder only. Also the cylinders are quite different shapes. Also the colours are for "the room is on fire, quick what's in that gas bottle over there?" situations. Are you allowed to be a safety responder if you're colour blind? For everyone else the rule is pretty simple; GTFO, and if acetylene is involved, GTFO out of the postcode.
        CamperBob2 14y ago
        Still, you don't go out of your way to pick confusing colors. This is Usability 101 stuff. If the room's on fire and I'm in it, I'm a 'safety responder' whether I want to be or not.
  - wnight 14y ago
    Video games have taught us that fire extinguishers blow up so it cancels out.
Nrsolis 14y ago
You're certain??? Better check your sources.
mpyne 14y ago
Only 1 U.S. submarine has ever had 2 nuclear reactors (bonus points for those who know why it was designed with 2). Soviet submarines often had 2 though. For the U.S. submarines they frequently would test shutting down the 1 operational reactor at-sea and trying to recover from the casualty, just to prove that it could be done when you didn't have time to pre-plan. Edit: U.S. subs do have diesels though. So next question: how do you bring up the diesel engine and its required auxiliaries without AC?
- Nrsolis 14y ago
  Nice try, Ivan. Remember, it's called the silent service for a reason. Those who know, don't tell; those who tell, don't know.
- joshAg 14y ago
  With a storeable dc power source, just like a car or truck. I suppose if that failed or had somehow discharged incorrectly, there should probably be a way to handcrank the diesel generator, like how early cars required hand cranking to start. PS: I had to look it up, but that's an interesting reason why that us sub had 2 nuclear reactors.
- angersock 14y ago
  Never been in the navy, so just guessing. Just kicking around ideas... Option A: You hand-crank the beast somehow? To get the glow-plug going, you again use a hand generator? Hopefully enough to bootstrap the generator (maybe it's a smaller generator that runs a larger one)? Generators all the way down? Option B: You blow ballast somehow and use the inrushing water to drive a turbine that runs the generator or gets it going? Option C: You manually pull the control rods and switch the coolant loop to run a small turbine to prime the generator? Option D: You mayday and get a jump from the Russian/Chinese/Iranian sub following you around? Option E: You try something dumb and dangerous with hydrogen peroxide from the torpedoes (I think/hope that that's phased out now)?
  - glurgh 14y ago
    I think it's mostly batteries, a sub operating at constant depth and in motion is negatively buoyant. If something goes wrong and it loses propulsion, power has to be available immediately to operate the systems that can handle the emergency - whether it's blowing ballast or restarting the reactor. This is a somewhat different constraint than the procedure described by the other reply - ships float without power, subs, not always. I mentioned this upthread - USS Thresher[1] seems to have suffered a loss of both propulsion and ballast control while near test-depth with, unfortunately, tragic results for the vessel and all on board. [1] http://en.wikipedia.org/wiki/USS_Thresher_(SSN-593) http://en.wikipedia.org/wiki/USS_Thresher_(SSN-593)

joshAg 14y ago

I can think of a few possible answers: 1) wouldn't you just insert/remove control rods as needed to restart the nuclear chain reaction? i'm pretty sure most reactors design control rods to be manually insertable/removable, even if there are other way to insert/remove them 2) a standby diesel generator with good ventilation, especially passive ventilation? 3) a large dc power source (ie big, charged batteries) to "jumpstart" either a diesel generator or the nuclear reactor the way my car battery jumpstarts my car when I turn the key 4) some other form of stored potential energy and a generator that can extract it (eg: compressed gas through a turbine) to start 1 or 2. 5) (really just a subsection of 4) human powered generator of some kind. perhaps a few stationary bikes?

arethuza 14y ago
Your mention of manual removal of control rods reminded me of the SL-1 reactor accident - where some unfortunate chap went to raise a control rod a few inches but accidentally pulled it out 26 inches - the resulting huge power surge and water hammer caused a very nasty accident killing all 3 operators: http://en.wikipedia.org/wiki/SL-1 http://en.wikipedia.org/wiki/SL-1
VLM 14y ago
#1 actually no, a lot of designs have a spring pulling the rod into the core, and an electromagnet sticking to the rod, so if the plant utterly loses power the rod snaps back into the core and can't be pulled out. In theory you could attach the rods to bypass the safety feature but its just not happening. Another issue is you run the coolant pumps to dump a couple MW into the system to reach operating temp/pressure after a day or so, THEN light off the reaction so you don't have varying steam conditions affecting the nuke physics. You don't "heat up" a nuke under nuke power as most assume. Its already thermally hot operating temp when you pull the rods.
- joshAg 14y ago
  so if i'm understanding correctly, from a black start it would take at least a day for the nuclear reactor to come online? then you'd need at least a couple diesel generators and fuel or power cells to get the reactor into a state where it could start generating power. Since you said megawatts, there will probably need to be a smaller generator or two to start the generators that will start the reactor, since i think MW diesel generators take a fair amount of work to get started themselves. And we haven't even talked about backup generators in separate parts of the boat/ship in case of engine fire/damage. Also, there would probably need to be at least another generator/power cell whose only job is to ensure that the sub can blow its ballast at any time (and of course, just regulate it) that comes up as soon as the reactor goes down.

glurgh 14y ago

Big ole batteries - you'd need them anyway to run systems in the first place, should the reactor be shut down at depth. It looks like something like, say, a Los Angeles class sub can actually run its generator from batteries "[...]power can be provided from the submarine's battery through the Ship Service Motor Generators (SSMGs)." This is a problem that the engineers designing nuclear submarines have thought long and hard about - the USS Thresher and all crew were lost in part due to inability to rapidly restart a scrammed reactor.

mpyne 14y ago
Congrats, great answer. Everything I learned on the boat just taught me that I have so much to learn. So many minor details that a ship designer thought up went into each successive class of U.S. submarine. There were many days when I'm surprised again that we haven't lost more submarines due to design flaws or misfeatures.
- glurgh 14y ago
  Hah, that is surely one of the many differences between reading about a sub and serving on one. Me: US navy nuclear submarines are a much-cited example of the successful design, development and deployment of high-reliability systems. You: I sometimes wonder how it is that more of us are not sleeping with the fishes. Still, everyone from designers to crews must be doing something right since it's apparently possible to drive such a machine into a rock at flank speed[1] or through a boat[2] or have it commanded by someone exhibiting strikingly poor judgement[3]. Without killing everyone on board and better yet, the planet. [1] http://en.wikipedia.org/wiki/USS_San_Francisco_(SSN-711)#Collision_with_seamount http://en.wikipedia.org/wiki/USS_San_Francisco_(SSN-711)#Col... [2] http://en.wikipedia.org/wiki/USS_Greeneville_(SSN-772)#The_Ehime_Maru_incident http://en.wikipedia.org/wiki/USS_Greeneville_(SSN-772)#The_E... [3] http://www.huffingtonpost.com/2013/04/12/michael-ward-affair_n_3071602.html http://www.huffingtonpost.com/2013/04/12/michael-ward-affair...

hudibras 14y ago

Finally, a HN thread that I can contribute to and I'm 9 hours late to the party. I was serving in the engineering department on a USN aircraft carrier (non-nuclear) when a cascading casualty led to all boilers going off line. The ship had an emergency diesel generator aligned to automatically power up, but it failed to start due to a previously-unknown problem. So an 80,000 ton warship with 5,000 people on board slowly drifted to a stop, completely dark except for emergency 60's-era-battle lanterns that were already starting to dim. No steam = no electricity (the normal ship's generators were steam-powered) and no electricity = no steam (because the start-up feedwater pumps and air blowers for the boilers were electric). One of the other two EDGs was already down with a casualty which left a single diesel generator that had to be started with compressed air stored in two huge bottles--so basically had two chances to get the ship moving again. (No electricity = no air compressors to refill the bottles.) After a few hours of double- and triple-checking the alignment of the diesels, electrical systems, and boilers (the original steam plant casualty had to be diagnosed) using flashlights in temperatures well into the triple digits (no electricity = no air condi...you get the idea) we successfully started the one remaining diesel which provided AC to the boilers to start up. By far the scariest day I ever had in the navy. Only saving grace was that we weren't flying planes at the time.

scrumper 14y ago
Interesting story, thanks for sharing. Glad I'm reading about it and not living it. I don't know much about this sort of thing, so I'll ask the obvious dumb question: why no batteries to start the diesel generator? Was it too big? Edit: Reading on, it seems like compressed air is the norm. Is it more space efficient than a battery big enough to start a large generator?
- hudibras 14y ago
  I think it was because the system was simpler and more reliable with no moving parts besides valves, just a giant air bottle with pipes leading to each of the cylinders. No motor to worry about or lead-acid batteries to maintain. The whole system probably took up way more room than a starter motor would but excessive space or weight is not a big concern on an aircraft carrier.