Japan....Unbelievable Hardship.

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Old 03-15-11, 05:47 PM
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Japan....Unbelievable Hardship.

I've had two TVs going for four days, those poor people and it's far from over yet.

Anyway, I've been trying to figure out all these explosions and fires at these reactors. If they stop the reactors automatically why is this still happening?

I came across this blog, if that's what it's called and found it pretty interesting:

msnbc.com technology & science - How a nuclear plant works

Naturally, there are some idiots but most are very informative. Here is one comment that seemed, to me at least, to explain a few things. Emphasis is mine.

==============================================

The problem is not continuing fission. Rods insert during an accident. The control/shutdown rods insert negative reactivity which halts the nuclear reaction. Rods are usually made of a material which has an enormous ability to absorb neutrons. Such as boron or halfnium.

In most GE BWRs (Boiling Water Reactor) the rods insert from the bottom of the core into the fuel assemblies – which contain rods – the rod insertion is spring assisted, or pressure assisted, and in some cases (not this one) gravity assisted.

The rods are made of zircaloy and contain pellets of uranium (in a ceramic matrix). Once the reaction is shutdown (which DID occur as designed) there is still decay to deal with. Long lived fission product continue too decay. These decay reaction also generate heat. How much? In the range of 5-7 percent of previous power! So a 1000MW Reactor running at 100% for an appreciable amount of time will generate aprx 60 Megawatts of power (heat equivalent of 60 MW is aprx 2.05 x 10 8 th BTU/HR). Knowing that a BTU is the amount of heat required to raise one pound mass (lbm) of standard water (at standard temp and press - STP) by one degree F. That is a lot of heat to be removed!

Now – when fuel reaches apx 2200 F a separate reaction begins and can become self sustaining. This reaction is called a zirc-water reaction and it produces massive heat and will dissociate H20 into hydrogen and oxygen. That’s where the H2 came from. They vented it into secondary containment blg rather than risk over pressure and an explosion in the primary containment bld.

Interesting stuff.
 
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Old 03-15-11, 07:25 PM
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when all this started they lost there power so that means they had no fresh water to pump in to cool it down, so they started pumping salt water in to cool it down which creates a gas that is explosive. paul
 
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Old 03-15-11, 08:56 PM
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Wouldn't sea water also release chlorine which is highly toxic and combine with hydrogen to produce hydrochloric acid rain?.
 
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Old 03-16-11, 04:54 AM
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Sort of like one of the dragsters at Yellow River back in the 60's. Engines cost a year's wages. One caught fire on start. Everyone raced to it and rather than Halon or inert gas, they pounded the engine with soda fire extinguishers. Engine running, sucking in soda granules. Engine total loss. Could have been saved with proper extinguishers, but that wasn't the priority.
Same theory, they are throwing at it all they have (an island surrounded by sea water) and aren't thinking of the long term effects. Put out the fire, so to speak.
Our prayers go out to them.
 
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Old 03-16-11, 04:39 PM
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Seawater coolant was backup #2 for this reactor.

IMO a very large part of the problenm is the media. I get so effing sick of the "oh my God we're all gonna die" reporting that I no longer pay any attention.

I'm not a Nuke but I worked around reactors for nearly 20 years and I was a qualified radiation worker for almost half of that. Much of what is being reported is nothing more than rumor and speculation reported as fact.

Now we have idiots in California buying iodine tablets and kelp.
 
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Old 03-16-11, 05:43 PM
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My wife lived there for 3 yrs..she says the image from the US news is soooo wrong. They don't show the people..they just have our commentators who assume things are the same as the US. Not true.
 
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Old 03-16-11, 07:42 PM
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Still learning here.

Seawater coolant was backup #2 for this reactor.
Not sure what you mean by this. From what I've heard, once seawater is put in the reactor itself, the reactor is unusable, TU. Now, seawater may be used to cool after it is turned into steam, but not in the reactor itself. Picture below from 2004 shows water outlets to sea and I don't see any huge cooling towers like we see at Three Mile Island. So, I'll guess they use seawater somewhere in the cooling process.





.... I no longer pay any attention.
Well....maybe you should. Take a look at the first picture, showing reactors 1-4 on the 12th, four days ago. Since then there has been an explosion or two and fires.

Satellite Photos - Japan Before and After Tsunami - Interactive Feature - NYTimes.com


Today it was reported, Japanese government denies it, that the cooling ponds on 5 or 6 has gone dry. We'll have to wait and see.

Japanese claim a power line is 'close' to being connected to get things up and running again. I hope so. You have to wonder though with the explosions and fires that anything will work as hoped.
 
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Old 03-16-11, 07:56 PM
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My wife lived there for 3 yrs..she says the image from the US news is soooo wrong. They don't show the people..they just have our commentators who assume things are the same as the US. Not true.
I think I'll have to disagree with you there. I guess it depends on which channel you watch. Diane Sawyer was over there (till her hair got dirty and she had to come home ) and reported about the coming rolling blackouts. Well, the blackouts weren't needed as the people sat by candlelight which she showed. I'd like to see that here...."hey, I need to keep my beer cold."

One more thing we don't see over there....looting. Good for them.
 
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Old 03-16-11, 08:18 PM
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Here's a much better photo I just found.....

 
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Old 03-17-11, 05:40 AM
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My understanding of the use of seawater was what you described. Once it's used the reactor is permanently ruined, so it's the last line of defense for emergency cooling.
 
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Old 03-17-11, 06:04 AM
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A guy from the NRC said that the plant was designed to use seawater cooling as an emergency backup if the normal cooling methods failed. I don't know if they are pumping seawater directly into the reactor or if the reactor was designed with a heat exchanger. That wasn't my point.

My problem is with the media playing on the fears and ignorance of people. As usual they are making a bad situation even worse with their sky is falling reporting.

As usual, the print media has done a better job than TV.
 
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Old 03-17-11, 06:08 AM
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Baldwin...thats what the wifey meant. No riots, no looting..its not their way.
 
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Old 03-17-11, 03:49 PM
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So in the end, what actually happens if things go even wronger? Do these fuel cells melt a hole into the earth and eventually come out the other side? Is there just one big explosion that spews radiation? So far, my limited tv watching doesn't really revail what end result catastrophe can occur.
 
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Old 03-17-11, 04:53 PM
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I think we've seen the worst that can happen at Chernobyl with a burning pile spewing radiation and radioactive particles. I don't expect Japan's plant to do anything like that. I think they will eventually get the magic glow sticks cooled down, salvage what they can and they'll sit on the rest for 3 or 4 years to cool down then they'll probably entomb the place with concrete and hang a sign saying "do not open for 10'000 years".
 
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Old 03-21-11, 06:40 AM
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Our thoughts and prayers go out to all affected by this catastrophe.
 
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