Seems like things are looking pretty grim right now. Does anyone know if those nuclear plants were damaged by the quake or by the tsunamis?
The reactors scrammed when the eathquake hit...this means they automatically shutdown. but it takes a long time for them to cool. The 1st cooling system was powered by electricity and the electricity was off due to the quake, so the operators went to their emergency diesel power. Not long later, the tsunami came along and took out the diesel fuel tanks, and maybe some of the generators as well. So they went to battery power, but it is only good for a few hours, hoping to get either dieel or regular electricty back. Unfortunately, because of the damage to infrastructure, they did not fget the right diesel parts back in time.
So, they began to vent steam as the pressure built.
Remember, nuclear reaction has ceased, they are just wanting to cool down the fuel and that takes quite a long time.
Ultimately, they began to use sea water to cool the cores. But even then, there is still a lot of heat and so they continue to vent.
What they are venting is generally not dangerous, particularly in the long term...but the hydrodgen has still seperated in some cases and so they vent that too and that is what has been causing the explosions. As far as I can tell, all of those have occurred outside of the containment structures and no containment structure has been breached.
The cores are designed to still contain the really dangerous radioactivity even if all cooling fails and there is a melt down. 1st, they are encased in a sheath as a first line that allows up to 2200 C or something like that. Then all of that is encased in a very well designed, very strong steel contaiment vessel, capable of over 3000 C. If it got to that point the core would drop into the concrete contaiment understructure which is supposed to hold and encase it until it cools down.
As I understand it, those direct containment methods have not been breached...they are still trying to cool it externally, venting steam as they went and it had some radioactivity in it...but very short half-life.
Here is a GREAT artcile here by an MIT expert on the technology. Best straight forward explanation I hvae read to date:
Read that article. I agree with his sentiments having worked the first several years of my career (in the early to mid eighties for Bechtel Power Coporation on the San Onofre and STP nuclear plants.
I really detest the way earthquake death tolls are reported. They seem to report only the confirmed/presumed dead, while putting the number of missing in small print buried somewhere in the article, if it's there at all.
It really understates the magnitude of the catastrophe. They really should put the number of missing in the headlines as well.
I agree as well. I believe the death toll will go over 100,000...and may approach or pass 200,000. Too many entoire small towns reported wiped out. One city reports 10,000 missing in that smaller city alone.
