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Merged nuclear power safe?

elgarak said:
...but still needs to be quite high (as you say, it's a reaction with steam, i.e. water vapor. Zircaloy does not react with liquid water).

The most likely conditions for that in Fukushima are found inside the pressure vessels.
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Strangely enough, Zircaloy is not supposed to burn and if it does ignite it would need copious amounts of oxygen to burn. Water would be the last thing you should throw at it.

This would cause more explosions. Dry powder is what should be used.
Remember the Falklands war and aluminum fires on navy ships.
 
ceptimus said:
Yours is the incorrect analogy.

In the case of this plant, the backup generators did work for a while, and then the batteries worked for a few hours after that. If it had been a plane, it would have safely landed long before all the backups failed.
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Assuming the engines had failed conveniently close to the nearest airport or, in fact, dry land.

If you want a better analogy for the nuclear power plant you should choose something like a Mars-mission spacecraft, where the backup systems would have to work reliably for months in order not to kill the passengers.
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And even then, when the next accident would take out your last remaining backup-systems, everybody would still die.

It's not elephants all the way down, you have a finite number of backup systems.
 
ceptimus said:
Yours is the incorrect analogy.

In the case of this plant, the backup generators did work for a while, and then the batteries worked for a few hours after that. If it had been a plane, it would have safely landed long before all the backups failed.

If you want a better analogy for the nuclear power plant you should choose something like a Mars-mission spacecraft, where the backup systems would have to work reliably for months in order not to kill the passengers.
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That's like saying if one engine had failed and another failed 5 mins later, the aircraft would have landed without problem. It's not quite that simple.


FWIW, I was a maintenance tech in the AF. I was responsible for troubleshooting/repair of the flight control and radio systems, including their redundancies. I've heard my share of "when the backup to the backup fails" stories.

The bottom line is that right now, the plant workers in Japan are attempting to land a 747 with no power. An amazing feat to behold, even if the aircraft isn't going to survive the landing.
 
ceptimus said:
Greetings to you too! :)

When a coal power plant or chemical plant is bombed or otherwise attacked during a war, the results are bad. But I think you would accept that they're not as bad for the surrounding area as a devastated nuclear plant.

Of course, some other sorts of power plant, such as hydro electric dams, may be very dangerous when bombed in a war - though the dangers are probably more acute. The nuclear contamination is more of a chronic problem - it may kill more people, but probably over a much greater time period.
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Yes, and no, and maybe.

For one, no one can say how many people would instantly die in each case. Then, for many things we don't really know what the long-term results will be at all. What we do know, however, is that coal plants, for example, have devastating implications for the area they are in. Ground and water contaminations, etc. No one can say what the implications will be of the BP oil disaster. Just because we don't see much of the spilled oil anymore does not mean that it isn't there.

And then, i'm generally very reluctant to accept any argument just based on the number of deaths, health implications, environmental impact, etc. in case of a disaster. That is just way too noarrowly focused.

By that argument we should get rid of all air planes immediatly, because in the case of a disaster, almost all of the people involved will die. This is just too short-sighted.

One must take into account the impacts and implications during the whole life-time of a plant or installation or whatever, even if that lifetime ends with a disaster. It may be nice to say "Well, duh, if a coal plant blows up, it's only a very limited impact from that". While this is true, it would neglect the impact it has during operation. Coal mining is dangerous and devestates a lot of land. Burning coal is extremely dirty, with a lot of poisons released.

While a nuke blowing up will have a big impact, it is still better off than a coal plant, all things considered.

That's one of the things i'm sorely missing in the whole debate, especially here in Germany. Yes, nukes are not without risks. Yes, a nuke gone mad can cause a lot of fatalities. Yes, radioactive materials released into the atmosphere isn't a good thing. But that's only a little part of the whole equation, but unfortunately it is only that part that gets the most attention.

Finally, one would be wrongly guided to judge nuclear technology only by the old, existing reactor designs. There are much safer design available now, even ones where a core meltdown simply can not happen. As an added extra, these designs also use up to 98% of their fuel, compared to a measily 0.6% of the older and current ones. And to make it even better, the fuel they use is much more abundant too. Much much more.

But thanks to the anti-nuke lobby, the efforts to develop and deploy these technologies are heavily crippled, and even stopped completely in some countries.

Greetings,

Chris

Edit: From what i understand, these new kinds of reactors (LFTR's, to be exact) can also be manufactured in smaller sizes and still be economical from a business perspective. This would allow for building many smaller reactors, in case of a few big ones, which would further reduce the overall risk and implications in case something goes awfully bad.
 
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Skwinty said:
Strangely enough, Zircaloy is not supposed to burn and if it does ignite it would need copious amounts of oxygen to burn. Water would be the last thing you should throw at it.

This would cause more explosions. Dry powder is what should be used.
Remember the Falklands war and aluminum fires on navy ships.
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Isn't metal fires typically obvious to those who try and fight them? Namely in that they are actually quite famous for being able to blind a person. I know aluminum and magnesium does but does zircaloy?
 
How much extra exposure is the surrounding area getting from "skyshine" of the gamma from the exposed pools?
 
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ceptimus said:
Yours is the incorrect analogy.
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Considering that all of the backups were wiped out due to natural causes, I'd say it was actually pretty good.

Of course, unless you are suggesting they should've moved the whole plant.

If it had been a plane, it would have safely landed long before all the backups failed.
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There are no backup engines on a plane.

Also, you are assuming that the plane is anywhere near land.

Of course, since you already have made up your mind, no analogy will ever work.
 
Rasmus said:
Assuming the engines had failed conveniently close to the nearest airport or, in fact, dry land.



And even then, when the next accident would take out your last remaining backup-systems, everybody would still die.

It's not elephants all the way down, you have a finite number of backup systems.
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Oh, no, no.

When we're talking about a nuclear plant in which all backup systems failed in short order, the correct analogy IS a 4-engine aircraft with one or two engines missing. :rolleyes:
 
technoextreme said:
Its rare but not impossible.
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Sure, I am not saying it is impossible, but the data sheet clearly states specific conditions are required and how to extinguish the fire.

If the fuel in the spent fuel pool was on fire, then I would have expected some fireworks when the helicopters started dropping water in the spent fuel pool.
 
The backup batteries worked (as designed) for eight hours. Any plane with a backup engine that worked for half that time would be able to make it to a runway.

That's what I'm saying is wrong with your 'all engines failed' analogy. The problem with a nuclear power station is that the backup systems have to continue to work for many days (at least). That's why I'm suggesting the spacecraft analogy might be more accurate.

Of course, any analogy is only useful until you try to push it too far.
 
Skwinty said:
Sure, I am not saying it is impossible, but the data sheet clearly states specific conditions are required and how to extinguish the fire.

If the fuel in the spent fuel pool was on fire, then I would have expected some fireworks when the helicopters started dropping water in the spent fuel pool.
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So essentially we said the same thing. My distinction was that most if not all metal fires are prone to seriously causing injury from afar without any of the flames coming in contact.
The backup batteries worked (as designed) for eight hours. Any plane with a backup engine that worked for half that time would be able to make it to a runway.
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Yes now how about if you have all three freaking hydraulic lines severed that route essential fluid to the control systems with the last backup system being an ugly kludge that most people conceided afterwards was next to impossible to use correctly.
 
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Skwinty said:
This would cause more explosions. Dry powder is what should be used.
Remember the Falklands war and aluminum fires on navy ships.
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Sorry, but I believe this is fallacious.

"Because of the widespread use of aluminium alloys in building, transport, home appliances and offshore structures, it is necessary to address the issue of aluminium and fire and to answer the question, 'does aluminium burn?'.
The answer is, of course, "No". Each year hundreds of thousands of tonnes of aluminium scrap are fed into remelt furnaces and heated up to and beyond the melting point. The aluminium melts when the temperature exceeds the melting point, it does not burn. If it did, the recycling of aluminium would not be possible.
During and following the Falklands conflict between Great Britain and Argentina ..... " (information)

source
 
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The discussion was about the the plant needing a reliable backup power source to guarantee safety.

Obviously you can posit failures of critical components that cause instant catastrophe - both to planes and nuclear power plants.

But the analogy of, say, a wing or tail surface breaking loose, would be more applicable to a nuclear reactor where the main pressure vessel suddenly cracked open.

I thought we were trying to come up with an analogy for how the incident (disaster?) has escalated gradually due to the lack of available power - and in the case of the reactor, SOME power was still available for many hours after the initial event. For most systems you can imagine (such as aircraft) that would be plenty long enough. A nuclear reactor of this type is unusual in that it requires the backup power to be available for days, weeks... and in that sense it is more like a spacecraft than a plane.
 
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