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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
by 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 agoNice 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 agoWith 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 agoNever 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 agoI 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)
- mpyne 14y agoOption F: Compressed air. Turns out mechanical systems are stupid simple to hand-power and yet can store a ton of energy usable without fancy equipment. Plus it turns out we might need compressed air for this no matter what depending on where the boat is at.
- angersock 14y agoAh, very cool. Oftentimes the crudest solutions are the best.
- The_Fox 14y agoHere's the black start procedure for the 1950's-era ship I worked on. No idea if this is at all similar to how they start diesels on a modern sub. 1. Hand-crank a small diesel engine connected to a small air compressor. 2. Use the small air compressor to build up pressure to start the emergency diesel generator. 3. Start the emergency diesel. 4. Using the emergency power, run one of the large air compressors to build up pressure for starting the main generators. 5. Start the main generators. The emergency diesel was near the stern of the ship, away from the generator room, to ensure an generator room fire couldn't take out the emergency diesel.
- angersock 14y agoI knew it! Generators all the way down!
- mpyne 14y agoIt's actually similar on a submarine, except that there's no need to hand-crank an air compressor as we have tons of compressed air already available on a submarine. Also, once the diesel is running it is used to power the electrical buses that provide the minimal pumps and other gear needed to recover the reactor and eventually restart (or emergency restart) the turbogenerators that provide ship's service power. Unfortunately there's no room to have separate emergency generators and emergency diesel so they are co-located.
- opminion 14y agoWater pressure?
- cpleppert 14y agoUSS Triton, needed high speed to shadow carrier groups
- hudibras 14y agoI would have also accepted: "needed two reactors because it was the only USN submarine with two shafts."
- mpyne 14y agoTechnically, you mean the only USN SSN with two shafts, but even that is incorrect. Nautilus was a conventionally-driven submarine with counter-rotating screws just like its diesel-electric WWII-era forebears. The first single-shaft U.S. submarine was a diesel research vessel, USS Albacore, which proved the feasibility of many innovations which were later ported over to the nuclear submarine fleet. USS Skipjack was the first nuclear submarine to include most of those features, including single-screw design.
- temp453463343 14y agoAll merchant ships are required to have enough compressed air for several starts (and we're talking about much larger diesel engines). I'd assume it's the same for a nuclear sub.