Sweden Nukes shutdown.
Sweden Nukes shutdown.
(OP)
See:
http://w ww.aftenpo sten.no/en glish/loca l/article1 409304.ece
I was told that there are 4 generators required to shut down the power plant. A transmission problem dropped the plant. Then during the resulting shutdown two of the four generators failed.
I thought reactors were made such that if the power failed things like control rods would drop into the core automatically quenching the reaction.
Questions:
Is the "problem" the stored energy in the system possibly causing damage to the core and closely coupled systems?
Why would half the generators fail in a facility where they must be tested fairly regularly?
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I was told that there are 4 generators required to shut down the power plant. A transmission problem dropped the plant. Then during the resulting shutdown two of the four generators failed.
I thought reactors were made such that if the power failed things like control rods would drop into the core automatically quenching the reaction.
Questions:
Is the "problem" the stored energy in the system possibly causing damage to the core and closely coupled systems?
Why would half the generators fail in a facility where they must be tested fairly regularly?
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com






RE: Sweden Nukes shutdown.
The key word is 'safety thinking'. Thinking does not mean practicing.
I have not done much work on the Swedish nuclear plants. But I remember one time. It was at the Forsmark plant during revision. I had my "action slot" between 00700 and 0900 a certain day. I was there well on time. But something screwed up, so I had to wait. And wait. Finally, at around 1800, I was told that I had turned into a "reportable event" and that my "action slot" didn't exist any more. A report was written and put in one of the loose-leaf binders that existed for that kind of unfinished work.
My memory of this is that it was binder number five or six that was used. The others were already filled with reports. I asked if they were all unfinished and the answer was affirmative. I then asked naïvely if that wouldn't constitute a risk? "No, we have several parallel safety systems. So it doesn't matter if one or two of them is out of order" was the answer I got.
I went home. But I had lost a lot of confidence in the Swedish safety thinking. And even more so in the way theory is practised.
Don't get me wrong. I am all for nuclear power. But the political situation has made it almost impossible to recruit qualified people to handle nuclear power. The government has a very poorly defined power policy. And it is dependent of a couple of minority parties that both use their influence to make things worse. So, not many want to work for nuclear power plants any more. On top of that, there is a law against "thinking nuclear" so it is only natural that the operators (human beings as they are) tend to simplify, ignore, rationalize, forget, eat up margins and so on. It is a sad state of affairs.
Gunnar Englund
www.gke.org
RE: Sweden Nukes shutdown.
And yes, the problem is the residual heat produced by the radioactive decay of the (spent) fuel. The heat must be removed by pumping water through the reactor. Electricity is needed for the pumps. If there is a blackout, and the emergency generators do not start, then "Forsmark, you have really a problem".
RE: Sweden Nukes shutdown.
RE: Sweden Nukes shutdown.
The core will most likely be unusable because of damage caused by the residual heat, but there should be no release of radio-active material. Dumping the D2O (deuterium oxide(heavy water)) is a last resort to be used only if two or three other levels of protection fail.
Safe but expensive.
respectfully
RE: Sweden Nukes shutdown.
"stear HPCI and RCIC"?????
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Sweden Nukes shutdown.
dsylectic fingers.
That should have been "steam powered HPCI ( High pressure coolant injection ) and RCIC (Reactor core injection coolant). There is a picture of a HPCI pump on this site. http://www.nucleartourist.com/areas/bwr-in1.htm
Fosmark is the vintage that would have them.
I have seen Terry turbines in refineries and paper mills, if you have spare steam there cheaper than a motor.
RE: Sweden Nukes shutdown.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com
RE: Sweden Nukes shutdown.
The answer is forever, the reaction is never quenched, the reactor is defined as subcritical after shutdown but heat is still being generated and flow must be maintained (Or be able to restart flow).
RE: Sweden Nukes shutdown.
RE: Sweden Nukes shutdown.
RE: Sweden Nukes shutdown.
Even though 'things happen' twould seem to me that separate redundant cooling loops with separately derived isolated power supplies would be danged reliable. Be interesting to read the report on the aforementioned fiasco.
Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com