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Old 03-16-2011, 05:00 PM
 
6,184 posts, read 4,600,585 times
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send the Emperor He looks like dust warmed up....
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Old 03-16-2011, 05:39 PM
 
Location: Over the Rainbow...
5,964 posts, read 6,905,798 times
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Quote:
Originally Posted by Moose Whisperer View Post
I will try, but it requires some technical explanation (sorry about the length).

Nuclear fuel bundles in an operating reactor produce allot of heat (obviously) due to the fission of Uranium.

When the reactor shuts down, the fission stops, however the highly radioactive fission products produced by the splitting Uranium atoms (Cesium, Strontium, Iodine, etc) continue to decay generating a lesser amount of heat. This is the “decay heat” we all have now heard of, and why Nuke plants require a shutdown or emergency cooling system of some kind even when they are "off”.

When a plant shuts down, Decay heat is initially 7% of Reactor Power (still quite capable of getting plenty hot) and gradually tapers off over the course of weeks to months.

If all power is lost at a shutdown plant and you can’t restore emergency cooling, the fuel heats up and can melt, as we have seen in this disaster.


If the fuel gets also uncovered (loses water) it will also burn - most metals burn if you get them hot enough (just take a match to a piece of steel wool if you don’t believe me).

Obviously all of this melting and burning (referred to as a “meltdown” in pop culture) destroys the physical integrity of the fuel rods and releases the highly radioactive fission products to go where they may.

In an operating reactor, this is obviously bad, but not catastrophic because everything is still inside of the Reactor Containment vessel and is prevented from escaping to the environment. This is after all what the containment is for – a final physical barrier in case of the worst case scenario.

This is what we see with Daiichi Units 1, 2, & 3.

Unit 4 however was shutdown at the time of the disaster for refueling.

This sounds good, however, the first step in the refueling process is to remove the (until just recently operating) fuel from the reactor and transfer it to the Spent Fuel Pool (SFP) – basically a big, concrete basin the size of several swimming pools, about 40 ft deep filled with water to keep the fuel cool and provide shielding since the fuel is highly radioactive. If you look at spent fuel in the pool, it actually glows an eerie blue because the radiation flux is so intense at the surface of the fuel.

The SFP has cooling systems, just like the reactor itself, to keep the spent fuel cool as the Decay Heat tapers off.

Now here’s the rub – the SFP is not within the reactor containment boundary.

In the Daiichi plant design, the SFPs sit in the reactor buildings – just a metal sided building not intended to be a pressure boundary. And due to all of the fires and explosions of late, the roof and sides of the reactor buildings have been blown off at Units 1, 2, 3, & 4.

So at U4 you now have high level, hot nuclear fuel EXPOSED DIRECTLY TO THE ENVIRONMENT. I’m sure if you flew over the site in a plane and looked down you could probably see the blue glow from the exposed fuel.

Now, this still isn’t a Chernobyl, that would require the fuel to explode and send everything into the atmosphere. That can’t happen. However, depending on how much decay heat is left, if they can’t cover this fuel quickly it will heat up and burn releasing the high level fission products directly to the atmosphere in the smoke plume.

Last I heard they were talking about bringing in water canons to shoot water on to the pool and cover it up. Problem is that spent fuel is so radioactive (now that it’s been uncovered) you can’t get within several hundred feet without getting a lethal dose of radiation.

Thank you Moose for explaining; yours was a little easier to understand then the article.
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Old 03-16-2011, 06:16 PM
 
901 posts, read 852,828 times
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The biggest problem Moose and I have even though we worked with nuclear is lack of factual information. We don't know the radiation levels for one thing. We don't know what the condition of the fuel bundles are. We can listen to the Gobbly **** being mouthed by those with far less knowledge and listen to some few who know the possibilities but no one can get close to the scene and come back alive and tell us what is going on. Any readings that are being made now are at best not good enough to set one scenario. At Three Mile Island it was years before they knew what had happened in the first hour because it took years to pick up small pieces and remove them so we could actually see what was left. This is much worse than TMI because nothing is contained. The worst part is there has never been anything like this to give us a clue as to what is going on. Chernobyl was a graphite reactor which is a totally different playtoy. Comparing it to this BWR is like comparing a firecracker to an atomic bomb. Carbon can burn which if you have ever used coal is a for sure. This is almost all metal which can get hot enough to vaporize or as is being said "meltdown" and scatter everything around. If they can get water on top of this mess and keep it there in years to come we might eventually find out what took place. None of the talking heads know what is actually going on right now. We know the possibilities but no one can look and see what is happening right now. It can be worse than Chernobyl but I'm not saying that is the case. This has never happened before so we are listening to people who don't know what they are talking about and need to remember that.
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Old 03-16-2011, 07:08 PM
 
6,184 posts, read 4,600,585 times
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I appreciate the insight. Truly. I know that you have posted prior that the airborne risk is minimal but I hope that you will keep looking at this and keep us up date. It is hard to keep all the opinions in perspective.

From a medical point of view cells which divide more quickly are more vulnerable to radiation so if that becomes an issue on the western coast youngsters babies and pregnant women or those that take care of them will want to stay current. In addition please don't automatically assume that potassium iodine can help. check with your doctor 1st before taking any supplement.
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Old 03-16-2011, 07:27 PM
 
Location: 112 Ocean Avenue
5,705 posts, read 4,574,946 times
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You'll be exposed to more radiation with one TSA screening that you'll ever be exposed to from the accident in Japan.

Try this next time you finish up with your TSA screening. Bet it'll light up.

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Old 03-16-2011, 07:32 PM
 
4,988 posts, read 5,362,069 times
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Quote:
Originally Posted by RedJacket View Post
Bet it'll light up.
Just pray it isn't BLUE!



Cerenkov | Causes of Color

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Old 03-16-2011, 07:49 PM
 
Location: on top of a mountain
7,016 posts, read 6,597,991 times
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Quote:
Originally Posted by Frostnip View Post
At the risk of sounding horribly heartless, it sounds like someone might need to pull a Spock here. Can't they hunt up a few terminally ill people who know how to operate a fire hose and want to go out as heroes or something?
excuse me??? as a person who is living on borrowed time I find this statement offensive.
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Old 03-16-2011, 07:53 PM
 
6,184 posts, read 4,600,585 times
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NHK World reports that Japanese authorities and the NRC Chairman could not be farther apart in terms of what they say is going on. Anyone who has been in the army knows exactly what that means.
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Old 03-16-2011, 07:55 PM
 
Location: Alaska 2001-2008
437 posts, read 390,031 times
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Really? I think there is much worse to think/worry about than whether you are going to be sterlile or bald. Like the people in Japan, in case you hadn't noticed.

Quote:
Originally Posted by FUNCTIONoverFORM View Post
So how strong will the radiation be when it hits AK? I'm assuming that if things don't get too much worse I won't have to worry about becoming sterile (4 gray) or bald (7 gray IIRC). Am I correct.
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Old 03-16-2011, 07:58 PM
 
6,184 posts, read 4,600,585 times
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Japanese now are attached lead plates to the bottom of the helicopters so that they can manually spray (fire hoses) the site from the air....= it's toast folks.

it's like watching a godzilla movie I swear..
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