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It sounds gruesome sure, but coal mines have had more gruesome accidents. They do say that newer nuclear plants simply will not have a Chernobyl or Fukushima s

It sounds gruesome sure, but coal mines have had more gruesome accidents. They do say that newer nuclear plants simply will not have a Chernobyl or Fukushima style meltdown by the way they’re designed. How to prove that conclusively - that may be tough

pdonis 3y ago
> They do say that newer nuclear plants simply will not have a Chernobyl or Fukushima style meltdown by the way they’re designed. No nuclear plant other than Chernobyl has ever had the possibility of a meltdown like the one Chernobyl had. As I posted upthread, Chernobyl is not a good proxy for any commercial reactor that has ever been built. Older plants do have the same decay heat removal failure mode that Fukushima has, but avoiding it is easy: don't put the backup power and switchgear where it might get flooded. (I am still surprised that the designers of that particular reactor at Fukushima missed this--particularly since other similar reactors on the same site did not.) Newer designs avoid that failure mode by having the coolant circulate by natural convection, so even with all power off, cooling flow still continues and decay heat still gets removed. This has been well understood for several decades (and US nuclear submarines have been using this capability for that long--they do it to remain quiet by avoiding the noise of coolant pumps, but the decay heat removal protection remains the same).
- reaperman 3y ago
  And if they’re attacked?
  - pdonis 3y ago
    Attacked for what purpose? Reactor fissionable material can't be used to make bombs. Anyway, if being attacked is a possibility, physical security for such plants isn't a hard problem.
  - deleted 3y ago
    [deleted]
  - njarboe 3y ago
    If French nuclear power plants are getting bombed, then France is in a full scale war. Since they have nuclear weapons I think the limited radioactivity from power plant bombing will be a minor problem compared to mushroom clouds over large cities. So people not realize large nuclear arsenals still exist?
- mfitton 3y ago
  I'm completely ignorant about nuclear power plants, so forgive me if this is a stupid question, but when we say that nuclear power plants today don't have the possibility of a similar meltdown, are we taking into account actions of an adversary? For instance, if someone dropped a sufficiently-sized bomb on a well-designed, modern nuclear power plant, would it melt down?
  - pdonis 3y ago
    > if someone dropped a sufficiently-sized bomb on a well-designed, modern nuclear power plant, would it melt down? No. It would just shut down. A big enough bomb could potentially spread some radioactive material around the plant area, but any adversary with access to a bomb that big and the ability to deliver it anywhere they chose could do much, much more damage by targeting other places.
    - reaperman 3y ago
      > potentially spread some radioactive material around the plant area I mean, I may be totally misunderstanding this. I thought this is what contaminated Europe's farmland more than the meltdown itself. Am I wrong? I'm not sure it's appropriate to just hand-wave it away. Pretty much all the farmland bombed across EU since WW2 could be used for agriculture shortly after each war ended. Whereas plenty of farmland still shouldn't be used today after being contaminated by "some radioactive material" that was spread around by Chernobyl. There's been some renewed analysis of this with the ongoing war in Ukraine which points to situations where more modern nuclear plants could indeed still be significantly worse than wind/solar: > Nuclear plants use a number of auxiliary safety systems, such as diesel generators and external grid connections, to keep reactors cool. Zaporizhzhia also uses a spray pond, a reservoir in which hot water from inside the plant is cooled. If those systems failed, then the nuclear reactor would heat up swiftly, triggering a nuclear meltdown. > “The main danger here is damage to the systems needed to keep the fuel in the reactor cool – external power lines, emergency diesel generators, equipment to dissipate heat from the reactor core,” Acton said. “In a war, repairing this equipment or implementing countermeasures could be impossible. In the worst case, the fuel could melt and spread large amounts of radioactivity into the environment.” https://www.cnn.com/2022/08/18/europe/zaporizhzhia-nuclear-plant-shelling-explainer-intl/index.html https://www.cnn.com/2022/08/18/europe/zaporizhzhia-nuclear-p...

pdonis 3y ago

> They do say that newer nuclear plants simply will not have a Chernobyl or Fukushima style meltdown by the way they’re designed. No nuclear plant other than Chernobyl has ever had the possibility of a meltdown like the one Chernobyl had. As I posted upthread, Chernobyl is not a good proxy for any commercial reactor that has ever been built. Older plants do have the same decay heat removal failure mode that Fukushima has, but avoiding it is easy: don't put the backup power and switchgear where it might get flooded. (I am still surprised that the designers of that particular reactor at Fukushima missed this--particularly since other similar reactors on the same site did not.) Newer designs avoid that failure mode by having the coolant circulate by natural convection, so even with all power off, cooling flow still continues and decay heat still gets removed. This has been well understood for several decades (and US nuclear submarines have been using this capability for that long--they do it to remain quiet by avoiding the noise of coolant pumps, but the decay heat removal protection remains the same).

reaperman 3y ago
And if they’re attacked?
- pdonis 3y ago
  Attacked for what purpose? Reactor fissionable material can't be used to make bombs. Anyway, if being attacked is a possibility, physical security for such plants isn't a hard problem.
- deleted 3y ago
  [deleted]
- njarboe 3y ago
  If French nuclear power plants are getting bombed, then France is in a full scale war. Since they have nuclear weapons I think the limited radioactivity from power plant bombing will be a minor problem compared to mushroom clouds over large cities. So people not realize large nuclear arsenals still exist?
mfitton 3y ago
I'm completely ignorant about nuclear power plants, so forgive me if this is a stupid question, but when we say that nuclear power plants today don't have the possibility of a similar meltdown, are we taking into account actions of an adversary? For instance, if someone dropped a sufficiently-sized bomb on a well-designed, modern nuclear power plant, would it melt down?
- pdonis 3y ago
  > if someone dropped a sufficiently-sized bomb on a well-designed, modern nuclear power plant, would it melt down? No. It would just shut down. A big enough bomb could potentially spread some radioactive material around the plant area, but any adversary with access to a bomb that big and the ability to deliver it anywhere they chose could do much, much more damage by targeting other places.
  - reaperman 3y ago
    > potentially spread some radioactive material around the plant area I mean, I may be totally misunderstanding this. I thought this is what contaminated Europe's farmland more than the meltdown itself. Am I wrong? I'm not sure it's appropriate to just hand-wave it away. Pretty much all the farmland bombed across EU since WW2 could be used for agriculture shortly after each war ended. Whereas plenty of farmland still shouldn't be used today after being contaminated by "some radioactive material" that was spread around by Chernobyl. There's been some renewed analysis of this with the ongoing war in Ukraine which points to situations where more modern nuclear plants could indeed still be significantly worse than wind/solar: > Nuclear plants use a number of auxiliary safety systems, such as diesel generators and external grid connections, to keep reactors cool. Zaporizhzhia also uses a spray pond, a reservoir in which hot water from inside the plant is cooled. If those systems failed, then the nuclear reactor would heat up swiftly, triggering a nuclear meltdown. > “The main danger here is damage to the systems needed to keep the fuel in the reactor cool – external power lines, emergency diesel generators, equipment to dissipate heat from the reactor core,” Acton said. “In a war, repairing this equipment or implementing countermeasures could be impossible. In the worst case, the fuel could melt and spread large amounts of radioactivity into the environment.” https://www.cnn.com/2022/08/18/europe/zaporizhzhia-nuclear-plant-shelling-explainer-intl/index.html https://www.cnn.com/2022/08/18/europe/zaporizhzhia-nuclear-p...