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Originally Posted by TLAM Strike
OK the way I understand it the pumps have a diesel backup power supply to keep them going if the reactor is shut down. When the Earthquake happened the reactors shut down automatically causing the diesels to kick in to keep the reactors cool but the tsunami damaged the backup generators (they have batteries as back up for that and those were put to use for a while). The tsunami also flooded the building(s) where the generators connect to the pumps. It was then decided to pump in sea water followed by boric acid to cool the reactor though the fire suppression piping (echos of K-19 here), this will ruin the reactor. Then an aftershock happened and they had to stop pumping in sea water, and then they ran out of sea water in their reservoirs.
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Here's a question: Why weren't the control rods designed to simply drop into the core in the event of a power failure to stop the reaction?
I'm not an expert on this stuff, but I have what would probably be best described as a casual interest in nuclear power-generation technology. From what I understand, a full application of control rods should be enough to stop any reaction the plant is capable of generating. If that is correct, why weren't the control rods released the moment the power failed? Feel free to stop me right here if I've got something wrong.
In any case, I spoke to a friend of mine who works in the BNSF corporate office the other day and she said she wasn't surprised by what happened to the Japanese reactors because many of their systems were designed by General Electric. To clarify, BNSF Railways Inc. does a lot of business with GE. She told me that GE has a history, in recent years, of designing failsafes that aren't really failsafes because they like to cut corners at the expense of quality.
Her assumption was that the Japanese reactor failsafes were probably a lot like the failsafes they installed on the engines of our DASH-9 CE-44W locomotives to prevent plasma arcing in the event of a current reversal; which is to say that they rely upon the other systems in the cheapest, most basic system they could design to power the failsafes, which seem to have been "tacked-on" after the original design was completed.
In our case, we've suffered some damage to locomotive engines because the computer that is supposed to prevent the electronically-relayed command to the generators to reverse direction, and therefore current flow (locos use DC power), doesn't always function properly. Under some emergency circumstances, it will allow a sudden reversal of current, which fries the hell out of the motors.
I wonder if this situation with the Japanese nukes is indicative of faulty GE engineering to cut corners in the same way - utilizing existing systems to power failsafes. It seems to me that a simple pneumatic or hydraulic system that would activate in the absence of current would be sufficient to propel the control rods into the reaction chamber, much as airbrakes on trains will apply in the absence of air pressure.
Thoughts?