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I'm really kind of sick of listening to people talk about how everything is hunky-dory. I heard one supposed expert on CNN basically state that a nuclear meltdo

by Duff 16y ago

I'm really kind of sick of listening to people talk about how everything is hunky-dory. I heard one supposed expert on CNN basically state that a nuclear meltdown is no big deal. The lesson to learn here is when a government tells you everything is ok regarding an event with potential regional impact, get the hell out of town. I'm assuming the reactors are melting down and are out of control. Pumping seawater in may be keeping the thing from blowing up, but obviously isn't cooling the reactors down. So what happens now? Do they keep melting down indefinitely, or do the reactions eventually fizzle out?

wallflower 16y ago
The worst case scenarios are bad: If one reactor gets so bad (meltdown) forcing permanent evacuation - all the remaining reactors won't be maintainable/saveable and thus in a domino effect - if one goes, all go (meltdown). It is unlikely that a meltdown through the core will occur but if that happens - the scary term China Syndrome - the melted radioactive fuel will melt through steel, concrete, rock, maybe even bedrock. For the USA and rest of the world: Irradiated food supplies will be a real concern if hundreds of tons of radioactive melted fuel merge with the outside environment To put it in perspective: If you were in Japan near Tokyo or closer to the affected nuclear plant, would you be more skeptical of the seemingly contradictory news coming out.
- forensic 16y ago
  Why would one meltdown cause evacuation? The meltdown would still be contained
  - marshray 16y ago
    Why would one meltdown cause evacuation? Because of fire, explosions, and excessive radiation exposure to workers. The meltdown would still be contained Containment is believed to have failed in reactor 2 and likely 3 at this point. Smoke or steam has been billowing from number 3 for hours now and its fuel is in the reactor, not the spent fuel pool.
btmorex 16y ago
That particular lesson was actually learned decades ago (see my comment 3 days ago http://news.ycombinator.com/item?id=2316593 http://news.ycombinator.com/item?id=2316593)
cperciva 16y ago
I heard one supposed expert on CNN basically state that a nuclear meltdown is no big deal. He's right, in a sense. Modern nuclear reactors are designed so that if the fuel melts it will end up in a wide concrete tray which sits under the reactor, where -- thanks to the fact that the tray is very wide and not at all deep -- it will cool down to a safe temperature. All good engineering works on the principle of defence in depth. This is the last step to safely contain the hot fuel, after the many redundant cooling systems fail, and it's certainly not ideal -- but it's nothing like the mythical "China syndrome". (Or like Chernobyl, which involved a graphite fire causing fuel to go up rather than down.)
- sliverstorm 16y ago
  I suspect your parent did not realize a nuclear meltdown simply means the melting of the fuel, and instead (like most people) simply directly associates the words with "huge disaster". (From that frame of reference of course- "a huge disaster would not be a big deal!"- it DOES sound ridiculous)
  - Duff 16y ago
    A few short days ago, we were told that everything was a-ok, no worries. Then the buildings started exploding -- still, everything is under control. On Monday we hear that fuel rods are fully exposed, but that is ok too. Now we're talking about the staff evacuating the site to avoid acute radiation poisoning and dropping seawater from helicopters. At what point do you stop accepting the best-case scenario as the most likely one?
    - sliverstorm 16y ago
      Well, I imagine when people are dying. The quake and resulting waves killed a lot of people. This hasn't, yet. Excuse me for thinking the most about those.
- timr 16y ago
  "All good engineering works on the principle of defence in depth." That line is as much a sound-bite at this point as anything you'll hear on cable television. Yes, good engineering has many levels of fall-backs and redundancies. But when you've reached the point that you've evacuated the last fifty people from your site because it's no longer safe for them to be there, then you've exhausted your defenses. There's no more depth. Let's stop whistling past the graveyard: a meltdown is, in fact, a really big deal. Maybe the "wide concrete tray" will capture the waste. Maybe it won't. But in the meantime, you're hoping that there's not a secondary fire from the heat, or a steam explosion, or some other kind of explosion that flings radioactive particulate for miles around. You're hoping that the fuel won't melt, form a critical mass in the bottom of the reactor, and re-initiate a reaction that's hard to stop. You're hoping that the containment doesn't breach, and that vast quantities of radioactive waste aren't exposed to the elements before the whole system calms down again. You're hoping that the whole system calms down again. The point is: they've lost control. The 'engineering' that they're doing right now is desperate and hacky, and they're very nearly out of options. It might be comforting to pretend that this whole thing is scripted out on some intricate Japanese checklist somewhere, but that's really nothing more than a fantasy. I certainly hope that things aren't as bad as they sound, but this isn't just a matter of bad PR by some pessimistic, nuclear-energy skeptics. These guys are actually in trouble.
Confusion 16y ago
According to the IAEA, Reactors 1-3 have been in cold shutdown since yesterday, which means they finally are where they were supposed to end up, in a stable situation where no water is boiling off anymore, so all the risk is gone.
- Confusion 16y ago
  Ai, I read it wrong. That was reactors 1-3 of the Daini station, not the Daiichi station.
- marshray 16y ago
  It seems that the IAEA is not a useful source of up-to-date information here. Apparently they're bound by agreements not to say anything without TEPCO's approval. The little they've said has been hours or days late. Unit 2 and 3 are believed to have lost containment integrity. Unit 3 is currently billowing smoke/steam.
  - paganel 16y ago
    > It seems that the IAEA is not a useful source of up-to-date information here. From the agency's statute page (http://www.iaea.org/About/statute_text.html#A1.2 http://www.iaea.org/About/statute_text.html#A1.2): > The Agency shall seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world. Now why would an Agency which is interested in "accelerating" the use of atomic energy for "prosperity" around the world say anything too negative about all this mess?
Groxx 16y ago
CNN seems to have been doing everything in their power to make things more confusing and worse than it actually has been. To make matters worse, right in the middle of them stating that the reactors were experiencing a meltdown (this is over a day ago), they cut back and forth between videos of the explosion and videos of a natural gas refinery on fire. Classy act, that; clearly they're interested in journalistic integrity and accuracy. The expert they had on was attempting to do away with some of the insane sensationalism they were trying to lead him to admit had minor accuracies in them.

by Duff 16y ago

wallflower 16y ago

The worst case scenarios are bad: If one reactor gets so bad (meltdown) forcing permanent evacuation - all the remaining reactors won't be maintainable/saveable and thus in a domino effect - if one goes, all go (meltdown). It is unlikely that a meltdown through the core will occur but if that happens - the scary term China Syndrome - the melted radioactive fuel will melt through steel, concrete, rock, maybe even bedrock. For the USA and rest of the world: Irradiated food supplies will be a real concern if hundreds of tons of radioactive melted fuel merge with the outside environment To put it in perspective: If you were in Japan near Tokyo or closer to the affected nuclear plant, would you be more skeptical of the seemingly contradictory news coming out.

forensic 16y ago
Why would one meltdown cause evacuation? The meltdown would still be contained
- marshray 16y ago
  Why would one meltdown cause evacuation? Because of fire, explosions, and excessive radiation exposure to workers. The meltdown would still be contained Containment is believed to have failed in reactor 2 and likely 3 at this point. Smoke or steam has been billowing from number 3 for hours now and its fuel is in the reactor, not the spent fuel pool.

btmorex 16y ago

That particular lesson was actually learned decades ago (see my comment 3 days ago http://news.ycombinator.com/item?id=2316593 http://news.ycombinator.com/item?id=2316593)

cperciva 16y ago

I heard one supposed expert on CNN basically state that a nuclear meltdown is no big deal. He's right, in a sense. Modern nuclear reactors are designed so that if the fuel melts it will end up in a wide concrete tray which sits under the reactor, where -- thanks to the fact that the tray is very wide and not at all deep -- it will cool down to a safe temperature. All good engineering works on the principle of defence in depth. This is the last step to safely contain the hot fuel, after the many redundant cooling systems fail, and it's certainly not ideal -- but it's nothing like the mythical "China syndrome". (Or like Chernobyl, which involved a graphite fire causing fuel to go up rather than down.)

sliverstorm 16y ago
I suspect your parent did not realize a nuclear meltdown simply means the melting of the fuel, and instead (like most people) simply directly associates the words with "huge disaster". (From that frame of reference of course- "a huge disaster would not be a big deal!"- it DOES sound ridiculous)
- Duff 16y ago
  A few short days ago, we were told that everything was a-ok, no worries. Then the buildings started exploding -- still, everything is under control. On Monday we hear that fuel rods are fully exposed, but that is ok too. Now we're talking about the staff evacuating the site to avoid acute radiation poisoning and dropping seawater from helicopters. At what point do you stop accepting the best-case scenario as the most likely one?
  - sliverstorm 16y ago
    Well, I imagine when people are dying. The quake and resulting waves killed a lot of people. This hasn't, yet. Excuse me for thinking the most about those.
timr 16y ago
"All good engineering works on the principle of defence in depth." That line is as much a sound-bite at this point as anything you'll hear on cable television. Yes, good engineering has many levels of fall-backs and redundancies. But when you've reached the point that you've evacuated the last fifty people from your site because it's no longer safe for them to be there, then you've exhausted your defenses. There's no more depth. Let's stop whistling past the graveyard: a meltdown is, in fact, a really big deal. Maybe the "wide concrete tray" will capture the waste. Maybe it won't. But in the meantime, you're hoping that there's not a secondary fire from the heat, or a steam explosion, or some other kind of explosion that flings radioactive particulate for miles around. You're hoping that the fuel won't melt, form a critical mass in the bottom of the reactor, and re-initiate a reaction that's hard to stop. You're hoping that the containment doesn't breach, and that vast quantities of radioactive waste aren't exposed to the elements before the whole system calms down again. You're hoping that the whole system calms down again. The point is: they've lost control. The 'engineering' that they're doing right now is desperate and hacky, and they're very nearly out of options. It might be comforting to pretend that this whole thing is scripted out on some intricate Japanese checklist somewhere, but that's really nothing more than a fantasy. I certainly hope that things aren't as bad as they sound, but this isn't just a matter of bad PR by some pessimistic, nuclear-energy skeptics. These guys are actually in trouble.

Confusion 16y ago

According to the IAEA, Reactors 1-3 have been in cold shutdown since yesterday, which means they finally are where they were supposed to end up, in a stable situation where no water is boiling off anymore, so all the risk is gone.

Confusion 16y ago
Ai, I read it wrong. That was reactors 1-3 of the Daini station, not the Daiichi station.
marshray 16y ago
It seems that the IAEA is not a useful source of up-to-date information here. Apparently they're bound by agreements not to say anything without TEPCO's approval. The little they've said has been hours or days late. Unit 2 and 3 are believed to have lost containment integrity. Unit 3 is currently billowing smoke/steam.
- paganel 16y ago
  > It seems that the IAEA is not a useful source of up-to-date information here. From the agency's statute page (http://www.iaea.org/About/statute_text.html#A1.2 http://www.iaea.org/About/statute_text.html#A1.2): > The Agency shall seek to accelerate and enlarge the contribution of atomic energy to peace, health and prosperity throughout the world. Now why would an Agency which is interested in "accelerating" the use of atomic energy for "prosperity" around the world say anything too negative about all this mess?

Groxx 16y ago

CNN seems to have been doing everything in their power to make things more confusing and worse than it actually has been. To make matters worse, right in the middle of them stating that the reactors were experiencing a meltdown (this is over a day ago), they cut back and forth between videos of the explosion and videos of a natural gas refinery on fire. Classy act, that; clearly they're interested in journalistic integrity and accuracy. The expert they had on was attempting to do away with some of the insane sensationalism they were trying to lead him to admit had minor accuracies in them.