Topic: Nuclear crisis in Japan at level 7

[Mormegil]

According to CNN: http://www.latimes.com/news/nationworld/world/la-sci-japan-reactor-damage-20110316,0,7701045.story

They only pulled back for an hour, and the pumps continued while they were gone.

All of the workers were pulled out of the plant for nearly an hour Wednesday when radiation levels spiked, but pumps continued to inject seawater into the reactors in their absence, according to Tokyo Electric Power Co, which owns the plant. The workers returned as soon as the radiation levels had subsided. The radiation spike was believed to result from the release of steam from reactor No. 2.

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     The reason for the helicopters is they need fresh water to put into the reactors and fuel rod pools.  You can't use salt water to surround the actual rods.  Or really bad shit happens.

[Chew]

     The reason for the helicopters is they need fresh water to put into the reactors and fuel rod pools.  You can't use salt water to surround the actual rods.  Or really bad shit happens.

They've been pumping salt water into the reactors for the last few days. Do you know what you're talking about?

[jaypee]

     The reason for the helicopters is they need fresh water to put into the reactors and fuel rod pools.  You can't use salt water to surround the actual rods.  Or really bad shit happens.

They've been pumping salt water into the reactors for the last few days. Do you know what you're talking about?

This is FX we're talking about here.

[Mormegil]

     The reason for the helicopters is they need fresh water to put into the reactors and fuel rod pools.  You can't use salt water to surround the actual rods.  Or really bad shit happens.

I don't think that's right.  According to TEPCO, they've been injecting sea water directly into the core.  Bad things happen when you do this, if you ever want to use the reactor again, but at this point, they've written these off.

Here's a gridded update of what's going on (updates every few hours using TEPCO data).
http://en.wikipedia.org/wiki/Timeline_of_the_Fukushima_nuclear_accidents#Tuesday_15_March

I think the reason for the helicopters is they can't get water in fast enough.

I'm not too worried about reactors 1-3, since they're in pressure vessels.  I'm worried about the #4 spent fuel pond, as it's not nearly as well contained.

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   I'm just reporting what a nuclear expert said.  It may have been nonsense.  Nuclear experts don't seem to know jackshit about what is happening.

[Chew]

   I'm just reporting what a nuclear expert said.  It may have been nonsense.  Nuclear experts don't seem to know jackshit about what is happening.

Where did you hear this expert?

[thelatinist]

I don't think that's right.  According to TEPCO, they've been injecting sea water directly into the core.  Bad things happen when you do this, if you ever want to use the reactor again, but at this point, they've written these off.

Well, there are other problems, as I understand it.  Seawater contains minerals which slow down neutrons, lowering the threshold for re-criticality.  This is why they are adding boronic acid to the seawater, to absorb some of the neutrons and hopefully keep the reactors from going critical.  If they were to go critical, there would not be much hope of preventing total meltdown.

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      If super hot zirconium causes electrolysis of water, I think salt water would be a really bad idea to have in contact with the fuel rods.   They may have been pumping sea water into the cooling pipes, but if they are putting salt water on the actual fuel rods, spent or active, that is a very bad thing to do.

[Mormegil]

I've heard it's not the electrolysis of water creating hydrogen (straight electrolysis requires much higher temps), but reaction with the Zn (oxidation), which releases hydrogen.  Yeah, it releases hydrogen, which is vented off (and can explode, as we've seen), but it's better than letting the rods melt, and possibly melt out of the containment vessel.


As far as the minerals in seawater goes, water itself is a neutron moderator, which can slow the neutrons down getting the reaction back to criticality.  I've heard the control rods Scrammed in were enough to ensure sub-critical mass, but the boric acid was added just as a safe measure, though they think it's unnecessary.


If they can keep up the cooling for at least a week on reactors 1-3, the decay heat is suppose to drop to 50% or so.  After that, it'll requires 2 or 3 more YEARS of cooling until the core can be removed (I think).

[Chew]

      If super hot zirconium causes electrolysis of water, I think salt water would be a really bad idea to have in contact with the fuel rods.   They may have been pumping sea water into the cooling pipes, but if they are putting salt water on the actual fuel rods, spent or active, that is a very bad thing to do.

The cooling pipes go directly into the reactor. It's a Boiling Water Reactor, you nimrod. Salt water will corrode the reactor, making it unusable, that is all.

[Will Nitschke]

The media reports I've seen this morning are that 3 of the cores are breached, one or more are venting hot steam directly into the atmosphere. A helicopter tried to douse one of the reactor's with water, but the radiation levels were too high.

[thelatinist]

The cooling pipes go directly into the reactor. It's a Boiling Water Reactor, you nimrod.

To be fair, this appears to be a common mistake on the 24-hour Panic networks, so perhaps he's just been watching too much Anderson Cooper.

[Will Nitschke]

The cooling pipes go directly into the reactor. It's a Boiling Water Reactor, you nimrod. Salt water will corrode the reactor, making it unusable, that is all.

I think at this stage everyone knows the reactors are a write-off. It's the very large amount of radioactive seawater that is a bother...

[Chew]

I've heard it's not the electrolysis of water creating hydrogen (straight electrolysis requires much higher temps), but reaction with the Zn (oxidation), which releases hydrogen.  Yeah, it releases hydrogen, which is vented off (and can explode, as we've seen), but it's better than letting the rods melt, and possibly melt out of the containment vessel.


As far as the minerals in seawater goes, water itself is a neutron moderator, which can slow the neutrons down getting the reaction back to criticality.  I've heard the control rods Scrammed in were enough to ensure sub-critical mass, but the boric acid was added just as a safe measure, though they think it's unnecessary.


If they can keep up the cooling for at least a week on reactors 1-3, the decay heat is suppose to drop to 50% or so.  After that, it'll requires 2 or 3 more YEARS of cooling until the core can be removed (I think).

Thermolysis of water happens at 2500^o C. I don't think it's gotten that hot yet.

The reactor was vented to prevent it from rupturing from the pressure, not to keep the fuel from melting.

If enough fuel melts it will fall to the bottom of the reactor and go critical. That is what the boric acid is for.

Decay heat at shutdown is 7% of total thermal power. After a week the decay heat will drop to 0.2%.