Quote:
Originally Posted by John Rogers
The subs today use natural circulation so the electric coolant pumps do not have to run. By this I mean when the reactor core gets the pressurized (2000 PSI or so) water hot it goes up to the steam generator where it makes 500 PSI water into steam and due to heat loss the reactor coolant then goes down to get reheated. The General Electric and early Westinghouse reactors used on the USS Enterprise and all the Cruisers were backwards, with hot water going down? Soooooo in the case of loss of power and no coolant pumps you had to get power back quickly to prevent core over heating!
Twice in the 20 years I spent as a nuclear machinist we lost all power twice on ships I was on and had trouble getting those big diesels started and would watch the core temperature meter like a hawk! At the D1G prototype training site in New York we did a test when core 3 was installed to see if natural circulation was possible.....it was not.
John
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There's still plenty of other pumps besides the reactor cooling pumps. Maybe the new reactors can have the primary side run on natural convection at low power levels but there are pumps to get condensate from the main condensor back to the steam generators, main sea water pumps to cool the steam coming into the condesor into condensate, trim and drain pumps, auxillary seawater pumps....
I got out in 91 and I'm going off memory. I remember the engine room upper level watch wearing head phones. I'm a bit dubious as to how much submarines have improved in the last 30 years. The basic layout of our boats hasn't really changed. One pressurized water reactor running two turbine electric generators and two turbines running the reduction gears turning one screw. I'll never get a tour of a Virginia class engine room so I don't know whats different about them but I doubt they're any difference, just everything is a little bigger.
You can postulate how much submarines have improved by just looking how big they have grown. The easiest way to make a pump quieter is to make it bigger and have it run slower. And then you make the bends in the piping have bigger radii. This all requires a bigger hull to provide the extra room and more displacement needed.
Anyone can go on wikipedia and look up the progressing submarine classes from the Skate, Skipjack, Permit, Sturgeon, Los Angeles, Seawolf, Virginia and see how they've grown.
The newest Japanese boats are still diesel electric but they're using modern batteries with a lot better energy density compared to the old lead acid technology of our last diesel electric boats built in the 50s.