5 ms·

Is it even possible to handle all contingencies though? I don't know enough to do the maths, but when you've got four different reactors an earthquake

by Tycho 16y ago

Is it even possible to handle all contingencies though? I don't know enough to do the maths, but when you've got four different reactors an earthquake followed by a tsunami followed by loss of electricity for the emergency pumps followed by parts of the plant blowing up followed by tons of dust getting in the way followed by possibly more aftershocks followed by possibly more tsunamis followed by possible injuries to the personnel needed to run these operations considering other equipment can break down considering political pressures to make certain decisions considering some of the physics/chemistry here may be entirely novel ... Think of all the different permutations in those variables, just how many scenarios have been prepared for? It has to be more complicated than just 'if casing 1 fails, casing 2 will stop it, and if casing 2 fails, casing 3 is there'

sandee 16y ago
It will not be possible ever, to keep handling cases of escalating complexity one of top of other. When things get complex beyond certain level, a kill switch should be triggered. The Kill switch should not depend on If-else cases ...
- drivebyacct2 16y ago
  And your response indicates compelete ignorance of both the situation and nuclear reactions. There is no kill switch, if they had a "kill switch" and executed it right now, you'd be condemning all the reactors to meltdowns, and you'd be condemning the US Western Coast to dangerous levels of radiation. The content of the fuel rods take DAYS to become non-radioactive enough for them to not need to be cooled constantly. The very problem that's occuring now is occuring because either the radioactive cesium and iodine is either at risk of not being cooled which will lead to a meltdown and release of them into the atmosphere, or a containment breach with largely the same impacts.
  - waterlesscloud 16y ago
    That's the basic problem with nuclear power, isn't it? There's no kill switch. It stops when it's ready to stop, not when you need it to stop.
    - drivebyacct2 16y ago
      All current efficient power sources have associated risks. It would be silly for anyone to call nuclear power 100% safe.
  - ErrantX 16y ago
    Hmm. What do you envision a "meltdown" to consist of? The system still has a fallback system in the event of a core meltdown that is designed to cool and manage the core without radiation release. Meltdown definitely does not equal to "release of them into the atmosphere". I'm not overly familiar with this specific reactor design; but usually what happens is they seal the containment as the core melts, flooding the sump (where the slag would collect) with water to cool it down. Right now they are trying to avoid that because a) there is always a risk of radiation leak from the containment and b) because the cleanup bill would catch quite a few more zeroes. The point is; meltdown is the final failure scenario, if they get to it, well, they get to it. But there is no fallback if something goes wrong at that point; so it is potentially better to try and control it at this stage, while you still have a fallback to implement. Please don't be overly dramatic ("and you'd be condemning the US Western Coast to dangerous levels of radiation"); this is a bad situation. But at the moment there does not appear to be a major risk to the US Western Coast. As you say, best not to comment in too much depth if you don't know the details.
    - drivebyacct2 16y ago
      >The system still has a fallback system in the event of a core meltdown that is designed to cool and manage the core without radiation release. What do you think is failing and is the entire cause for all of this concern. The fallback system is pumping water into the reactor to keep it cool. Those are the systems that have been failing and have failed (during the explosions/fires) and have caused the (temporary-ish) meltdowns in the last few days. A full meltdown has the potential to release a significant amount of radiation. A full meltdown increases in possibility as the reactors become harder to control and cool due to explosions and containment failure. It probably doesn't pose a significant risk to CA, but they will receive some radiation if it were actually to experience complete failure. Meltdown isn't binary. They're experiencing meltdown right now. By definition. That's what the release of radioactive material is. The question is, can they keep it under relative control and prevent further exposure of the still proceeding fuel rods.
      - ErrantX 16y ago
        They're experiencing meltdown right now. By definition. That's what the release of radioactive material is. Not really; in this case "meltdown" refers to the actual process of core melting, it is not entirely clear but it does not appear much or any of the cores have melted. Certainly not to the stage I would refer to as a meltdown. They are still in a "struggling to cool it down" stage. The release of radioactive material is not equatable to a meltdown - all manner of things can lead to such a release, meltdown is just one of them. If they actually have a full core melt (to the point it drops out of the reactor vessel into the dry well), yes, the risk of release of radioactive material is heightened. But probably not to the level you envision, and it is certainly not a case of "if it melts it's game over". Explosions within the reactor shell are extremely unlikely, even in the event of a core meltdown, because the system is specifically designed to stop such an event occurring (which is one reason it has not so far happened :)). Note; containment failure has not occurred, as far as we know, at any stage. The reactors are not being "controlled", the process is stopping by itself. The reactors simply have to be kept cool while that happens. What do you think is failing and is the entire cause for all of this concern. There is a different system in such a case (or, rather, a different approach). Essentially they just flood it with water. With the best will in the world; it is worth reading some of the more technical explanations rather than just the media. They explain the process and the issues much better - even Wikipedia has reasonable material (and is at least a place to start with links)
- nl 16y ago
  They had a kill switch and used it (the stopped the reactors as soon as the tsunami warning occurred). That hasn't helped, though, because a nuclear reactor takes months/years to become "safe" (depending on exactly what you measure and consider safe)
  - gjm11 16y ago
    In what sense is it true that "that hasn't helped"? Are you suggesting that if they'd kept the reactors running things would have been better? Perhaps what you mean is "hasn't made the impact of a magnitude-9 earthquake and tsunami zero". Honestly, I can't see that that's a reasonable thing to ask for.
    - nl 16y ago
      It "hasn't helped" in the context of the post I was replying to. The poster clearly thought that a kill switch would be some kind of magic button that would turn everything off and "make it safe". I'm pointing out that nuclear power stations don't work like that. Clearly, it is a much better situation now than if they had been going when the tsunami hit.
nl 16y ago
The first 10 things you have listed there are entirely predictable. Indeed, the emergency procedures were designed to handle them and simply haven't coped. They were unlucky that the tsunami was slightly worse than they had planned for, which washed away the diesel backup generators. Backups for those generators were quickly brought in, though. OTOH, they have been very lucky that no aftershocks have caused any tsunamis (yet). If that happened right now then they are screwed. I haven't seen any evidence of the last two occurring.
- gnosis 16y ago
  "what appears to have happened is the tsunami flooded the basements where these emergency diesel generator connections are at. So, even though they brought in mobile units, new emergency diesel generators, to hook them up to run the safety systems, the basements were flooded, where they needed to do the hook-up." http://www.democracynow.org/2011/3/14/japan_facing_biggest_catastrophe_since_dawn http://www.democracynow.org/2011/3/14/japan_facing_biggest_c...
  - nl 16y ago
    I guess that was something that was pretty predicable too: a Tsunami floods basements - who would ever have thought of that!? In their defense here though, I believe they got that pumped out pretty quickly.
- deleted 16y ago
  [deleted]
- Kliment 16y ago
  Slightly worse? They were designed to withstand 8.2 earthquakes, they got an 8.9 earthquake. That's not "slightly worse", it's seven TIMES worse. The scale is logarithmic.
- stewbrew 16y ago
  Yesterday I heard somebody who was responsible for a nuclear power plant in Europe speak on the radio (in Europe too). He said they were prepared for a malfunctioning valve, power outage etc. (predictable events) but they weren't actually prepared for the case that everything happens at once.

by Tycho 16y ago

sandee 16y ago

It will not be possible ever, to keep handling cases of escalating complexity one of top of other. When things get complex beyond certain level, a kill switch should be triggered. The Kill switch should not depend on If-else cases ...

drivebyacct2 16y ago
And your response indicates compelete ignorance of both the situation and nuclear reactions. There is no kill switch, if they had a "kill switch" and executed it right now, you'd be condemning all the reactors to meltdowns, and you'd be condemning the US Western Coast to dangerous levels of radiation. The content of the fuel rods take DAYS to become non-radioactive enough for them to not need to be cooled constantly. The very problem that's occuring now is occuring because either the radioactive cesium and iodine is either at risk of not being cooled which will lead to a meltdown and release of them into the atmosphere, or a containment breach with largely the same impacts.
- waterlesscloud 16y ago
  That's the basic problem with nuclear power, isn't it? There's no kill switch. It stops when it's ready to stop, not when you need it to stop.
  - drivebyacct2 16y ago
    All current efficient power sources have associated risks. It would be silly for anyone to call nuclear power 100% safe.
- ErrantX 16y ago
  Hmm. What do you envision a "meltdown" to consist of? The system still has a fallback system in the event of a core meltdown that is designed to cool and manage the core without radiation release. Meltdown definitely does not equal to "release of them into the atmosphere". I'm not overly familiar with this specific reactor design; but usually what happens is they seal the containment as the core melts, flooding the sump (where the slag would collect) with water to cool it down. Right now they are trying to avoid that because a) there is always a risk of radiation leak from the containment and b) because the cleanup bill would catch quite a few more zeroes. The point is; meltdown is the final failure scenario, if they get to it, well, they get to it. But there is no fallback if something goes wrong at that point; so it is potentially better to try and control it at this stage, while you still have a fallback to implement. Please don't be overly dramatic ("and you'd be condemning the US Western Coast to dangerous levels of radiation"); this is a bad situation. But at the moment there does not appear to be a major risk to the US Western Coast. As you say, best not to comment in too much depth if you don't know the details.
  - drivebyacct2 16y ago
    >The system still has a fallback system in the event of a core meltdown that is designed to cool and manage the core without radiation release. What do you think is failing and is the entire cause for all of this concern. The fallback system is pumping water into the reactor to keep it cool. Those are the systems that have been failing and have failed (during the explosions/fires) and have caused the (temporary-ish) meltdowns in the last few days. A full meltdown has the potential to release a significant amount of radiation. A full meltdown increases in possibility as the reactors become harder to control and cool due to explosions and containment failure. It probably doesn't pose a significant risk to CA, but they will receive some radiation if it were actually to experience complete failure. Meltdown isn't binary. They're experiencing meltdown right now. By definition. That's what the release of radioactive material is. The question is, can they keep it under relative control and prevent further exposure of the still proceeding fuel rods.
    - ErrantX 16y ago
      They're experiencing meltdown right now. By definition. That's what the release of radioactive material is. Not really; in this case "meltdown" refers to the actual process of core melting, it is not entirely clear but it does not appear much or any of the cores have melted. Certainly not to the stage I would refer to as a meltdown. They are still in a "struggling to cool it down" stage. The release of radioactive material is not equatable to a meltdown - all manner of things can lead to such a release, meltdown is just one of them. If they actually have a full core melt (to the point it drops out of the reactor vessel into the dry well), yes, the risk of release of radioactive material is heightened. But probably not to the level you envision, and it is certainly not a case of "if it melts it's game over". Explosions within the reactor shell are extremely unlikely, even in the event of a core meltdown, because the system is specifically designed to stop such an event occurring (which is one reason it has not so far happened :)). Note; containment failure has not occurred, as far as we know, at any stage. The reactors are not being "controlled", the process is stopping by itself. The reactors simply have to be kept cool while that happens. What do you think is failing and is the entire cause for all of this concern. There is a different system in such a case (or, rather, a different approach). Essentially they just flood it with water. With the best will in the world; it is worth reading some of the more technical explanations rather than just the media. They explain the process and the issues much better - even Wikipedia has reasonable material (and is at least a place to start with links)
nl 16y ago
They had a kill switch and used it (the stopped the reactors as soon as the tsunami warning occurred). That hasn't helped, though, because a nuclear reactor takes months/years to become "safe" (depending on exactly what you measure and consider safe)
- gjm11 16y ago
  In what sense is it true that "that hasn't helped"? Are you suggesting that if they'd kept the reactors running things would have been better? Perhaps what you mean is "hasn't made the impact of a magnitude-9 earthquake and tsunami zero". Honestly, I can't see that that's a reasonable thing to ask for.
  - nl 16y ago
    It "hasn't helped" in the context of the post I was replying to. The poster clearly thought that a kill switch would be some kind of magic button that would turn everything off and "make it safe". I'm pointing out that nuclear power stations don't work like that. Clearly, it is a much better situation now than if they had been going when the tsunami hit.

nl 16y ago

The first 10 things you have listed there are entirely predictable. Indeed, the emergency procedures were designed to handle them and simply haven't coped. They were unlucky that the tsunami was slightly worse than they had planned for, which washed away the diesel backup generators. Backups for those generators were quickly brought in, though. OTOH, they have been very lucky that no aftershocks have caused any tsunamis (yet). If that happened right now then they are screwed. I haven't seen any evidence of the last two occurring.

gnosis 16y ago
"what appears to have happened is the tsunami flooded the basements where these emergency diesel generator connections are at. So, even though they brought in mobile units, new emergency diesel generators, to hook them up to run the safety systems, the basements were flooded, where they needed to do the hook-up." http://www.democracynow.org/2011/3/14/japan_facing_biggest_catastrophe_since_dawn http://www.democracynow.org/2011/3/14/japan_facing_biggest_c...
- nl 16y ago
  I guess that was something that was pretty predicable too: a Tsunami floods basements - who would ever have thought of that!? In their defense here though, I believe they got that pumped out pretty quickly.
deleted 16y ago
[deleted]
Kliment 16y ago
Slightly worse? They were designed to withstand 8.2 earthquakes, they got an 8.9 earthquake. That's not "slightly worse", it's seven TIMES worse. The scale is logarithmic.
stewbrew 16y ago
Yesterday I heard somebody who was responsible for a nuclear power plant in Europe speak on the radio (in Europe too). He said they were prepared for a malfunctioning valve, power outage etc. (predictable events) but they weren't actually prepared for the case that everything happens at once.