8 ms·

>> What happens when the ultimate heat sink is lost? What's an example event where the ultimate heat sink might be lost?

ColanR 6y ago
No expert, but if it's a pool of water then an earthquake might cause a leak?
- newacct583 6y ago
  Or an attack, of course. Or some other event (social unreset, invasion, coup, etc...) causes an evacuation of staff and it boils off during the resulting excursion. People tend to have poor mental models for the long tail of external failures that happen in real life. It's easy to imagine that things that have never happened in the last century would Never Happen. But... they will, somewhere.
  - godelski 6y ago
    Nuclear sites are designed to withstand a strike from a commercial airliner (747). Like you, the designers imagined many of the events you mentioned and more. A good rule of thumb is that if you, a non-expert, can think of a scenario within 10 minutes, an expert has probably already thought of this scenario. Nuclear power plants and weapons sites have always been considered targets and thus considered extra scrutiny in their design.
    - thekyle 6y ago
      Wow. How do they design them to withstand a strike from a 747? That seems really difficult.
      - selectodude 6y ago
        A whole lot of concrete, mostly.
      - throwaway0a5e 6y ago
        They shot an F4 target drone at a block of "reactor grade" concrete wall back in the 80s and they took measurements and did science on the resulting lack of damage and concluded that a reactor can shrug off one of anything. They didn't change containment buildings to be plane proof. It's just a side effect of the design required to contain a melting down reactor with a sufficient safety factor.
        throwaway0a5e 6y ago
        video of the test https://www.youtube.com/watch?v=F4CX-9lkRMQ https://www.youtube.com/watch?v=F4CX-9lkRMQ
      - petre 6y ago
        Yes. A NRC requirement for utility scale reactors after 9/11. One wonders why nuclear reactors are so expensive.
        HPsquared 6y ago
        It's a good reason to design reactors to be as small as possible, with a small containment building. Much easier to build.
    - shortandsweet 6y ago
      You'd hope so. Reactors yes, but not spent fuel pools. Everyone misses things. I've found 3 design flaws myself in the industry. Not too big of a deal as actions can be taken to mitigate some of the flaws. The other flaws are less probable of causing an issue due to redundant and diverse systems but there's always the off chance...
      - throwaway0a5e 6y ago
        >but not spent fuel pools. Everyone misses things Everyone who remembers the post 9/11 "but what if the terrorists attack X" pandemonium knows that spent fuel pools are outside the containment building. That was one of the scenarios that got paraded around to maximize FUD.
        drran 6y ago
        I was involved in closing of case, when terrorists wanted to create dirty bomb and throw it at Ukraine. S*it happens.
        godelski 6y ago
        Wanted to is very different than doing. As far as I'm aware there has never been a dirty bomb attack. You could effectively create a dirty bomb with less radiation with more easily obtainable materials (still pretty expensive and labor intensive). The threat would be similar to a more radioactive substance because the biggest damage is the fear (that's what terrorism is about. They could do MUCH more _damage_ if they weren't as concerned about striking fear). The reason it hasn't been done is because it is impractical and difficult to do without killing yourself. There's better and far easier ways to strike fear into people's hearts. Killing a single person is more effective for them than increasing the chance of getting cancer in one's lifetime by 10% for a dozen people. The much bigger threat is a briefcase nuke but that is several more orders of magnitude difficult/expensive to obtain.
        drran 6y ago
        There is plenty of people which want to kill themselves for few, but common reasons, like cancer. It's not a stopper for terrorists.
    - ktal 6y ago
      https://interestingengineering.com/crashed-jet-nuclear-reactor-test https://interestingengineering.com/crashed-jet-nuclear-react...
    - pvaldes 6y ago
      > the designers imagined many of the events you mentioned and more Designers are awesome. Sadly they were also unable to find some time in 50 years to raise a wall a few m so it can stand a Tsunami. It seems that the extra scrutiny, was not so extra in the real life when the company will need to allocate real money.
      - godelski 6y ago
        The event you are referring to was also a freak event. The Tohoku earthquake was the 4th largest _ever_ recorded and the largest ever recorded in Japan (by 0.2M, it is a log scale btw). The closest earthquake to that, in the region, in the previous 100 years was 0.7M lower (and the 6th largest ever recorded, in the area). The Tohoku earthquake also resulted in one of the largest tsunamis ever recorded. We should note that a lot of rare things happened all at once, more than just the freak earthquake and freak tsunami. There is no such thing as perfect. But consider that there were no lives lost due to the reactor accident. Yes, there is economic damage, but that is the worst. Lives were not lost and the environment was not irreparably damaged. Nature has actually started to take back the region and it more looks like a scene out of I Am Legend rather than The Road or The Book of Eli. I do not intend to dismiss the event, as it is concerning (and we've learned a lot since then), but however you measure it coal or oil or gas have had far greater environmental (or human/health) impacts than nuclear. The difference is that it is more in our mind. Despite the Fukushima cleanup estimate (2x Chernobyl's) costing about 9x Deep Water Horizon (2010) I'll let you decide what costs more[0], even if we ignore all the costs to health and atmosphere. There simply is no free lunch. [0] https://ourworldindata.org/oil-spills https://ourworldindata.org/oil-spills
        NorthOf33rd 6y ago
        There’s no free lunch but wind and solar are a hell of a lot cheaper than this.
        godelski 6y ago
        Economically cheaper, but that isn't the only factor that we're discussing. We're also talking health and environmental.
  - p1mrx 6y ago
    > an evacuation of staff and it boils off during the resulting excursion. It is trivial to design a system that powers off when unstaffed. Without power, this reactor will SCRAM and passively switch to air cooling over the course of a month. Presumably, a skilled attacker could compromise the passive safety systems and force a meltdown, but wouldn't it be easier to steal some spent fuel and disperse it?
    - hansthehorse 6y ago
      Once an attacker is inside the plant, with just some Wiki knowledge, any plant is as good as melted down. It's a much better plan to simply drain the spent fuel pool.
      - p1mrx 6y ago
        I think it takes a bit more than Wiki knowledge to drain an in-ground pool... you would need to keep a large pump running for hours, under duress.
- sandworm101 6y ago
  You don't need to be an expert. Ask anyone who has owned an in-ground pool. Leaks are rare but do happen.
  - godelski 6y ago
    Nuclear power plants were designed with this in mind. It would take a substantially larger earthquake to damage a nuclear power plant and cause it to leak than a commercial pool. Such a comparison is in bad faith and disingenuous.
    - AnimalMuppet 6y ago
      Cool it (pun intended) with the accusations of bad faith. Unless you have enough data to prove it, don't accuse it. "Substantially larger" is not the same as "impossible". And, given substantially larger consequences if a reactor pool breaks (compared to a swimming pool breaking), I don't think the question is out of line. We learned from Fukushima that natural disasters don't always follow the parameters that we expect them to.
    - ses1984 6y ago
      It's a people problem. People are fallible on the best days, assuming everyone did their very best from nuclear physicists to construction workers, mistakes are made. You take steps to reduce the risk. Research gets review. Engineering schematics get review. Construction gets inspection. Still some mistakes will get through. And people always act their very best all the time right? You can even have a perfect design, perfect construction, that is mismanaged years after it's built, after the original engineers and bureaucrats lose control. The same people problems apply to basically every human endeavor, but nuclear's capability to cause accidents that have a lasting impact is pretty scary. You don't feel even a twinge of existential dread when you think about? If you don't, then I don't think I want you working on a reactor.
      - markvdb 6y ago
        This. Humans are spectacularly bad at this kind of scale in time/project budget/size...
- dylan604 6y ago
  evaporation?
brandmeyer 6y ago
Many inland rectors are built on waterways. A plant can shut down due to drought. That's a slow enough process that you have plenty of advance warning, though.
- jhallenworld 6y ago
  Some are built on man-made reservoirs held together with dams..

ColanR 6y ago

No expert, but if it's a pool of water then an earthquake might cause a leak?

newacct583 6y ago
Or an attack, of course. Or some other event (social unreset, invasion, coup, etc...) causes an evacuation of staff and it boils off during the resulting excursion. People tend to have poor mental models for the long tail of external failures that happen in real life. It's easy to imagine that things that have never happened in the last century would Never Happen. But... they will, somewhere.
- godelski 6y ago
  Nuclear sites are designed to withstand a strike from a commercial airliner (747). Like you, the designers imagined many of the events you mentioned and more. A good rule of thumb is that if you, a non-expert, can think of a scenario within 10 minutes, an expert has probably already thought of this scenario. Nuclear power plants and weapons sites have always been considered targets and thus considered extra scrutiny in their design.
  - thekyle 6y ago
    Wow. How do they design them to withstand a strike from a 747? That seems really difficult.
    - selectodude 6y ago
      A whole lot of concrete, mostly.
    - throwaway0a5e 6y ago
      They shot an F4 target drone at a block of "reactor grade" concrete wall back in the 80s and they took measurements and did science on the resulting lack of damage and concluded that a reactor can shrug off one of anything. They didn't change containment buildings to be plane proof. It's just a side effect of the design required to contain a melting down reactor with a sufficient safety factor.
      - throwaway0a5e 6y ago
        video of the test https://www.youtube.com/watch?v=F4CX-9lkRMQ https://www.youtube.com/watch?v=F4CX-9lkRMQ
    - petre 6y ago
      Yes. A NRC requirement for utility scale reactors after 9/11. One wonders why nuclear reactors are so expensive.
      - HPsquared 6y ago
        It's a good reason to design reactors to be as small as possible, with a small containment building. Much easier to build.
  - shortandsweet 6y ago
    You'd hope so. Reactors yes, but not spent fuel pools. Everyone misses things. I've found 3 design flaws myself in the industry. Not too big of a deal as actions can be taken to mitigate some of the flaws. The other flaws are less probable of causing an issue due to redundant and diverse systems but there's always the off chance...
    - throwaway0a5e 6y ago
      >but not spent fuel pools. Everyone misses things Everyone who remembers the post 9/11 "but what if the terrorists attack X" pandemonium knows that spent fuel pools are outside the containment building. That was one of the scenarios that got paraded around to maximize FUD.
      - drran 6y ago
        I was involved in closing of case, when terrorists wanted to create dirty bomb and throw it at Ukraine. S*it happens.
        godelski 6y ago
        Wanted to is very different than doing. As far as I'm aware there has never been a dirty bomb attack. You could effectively create a dirty bomb with less radiation with more easily obtainable materials (still pretty expensive and labor intensive). The threat would be similar to a more radioactive substance because the biggest damage is the fear (that's what terrorism is about. They could do MUCH more _damage_ if they weren't as concerned about striking fear). The reason it hasn't been done is because it is impractical and difficult to do without killing yourself. There's better and far easier ways to strike fear into people's hearts. Killing a single person is more effective for them than increasing the chance of getting cancer in one's lifetime by 10% for a dozen people. The much bigger threat is a briefcase nuke but that is several more orders of magnitude difficult/expensive to obtain.
        drran 6y ago
        There is plenty of people which want to kill themselves for few, but common reasons, like cancer. It's not a stopper for terrorists.
  - ktal 6y ago
    https://interestingengineering.com/crashed-jet-nuclear-reactor-test https://interestingengineering.com/crashed-jet-nuclear-react...
  - pvaldes 6y ago
    > the designers imagined many of the events you mentioned and more Designers are awesome. Sadly they were also unable to find some time in 50 years to raise a wall a few m so it can stand a Tsunami. It seems that the extra scrutiny, was not so extra in the real life when the company will need to allocate real money.
    - godelski 6y ago
      The event you are referring to was also a freak event. The Tohoku earthquake was the 4th largest _ever_ recorded and the largest ever recorded in Japan (by 0.2M, it is a log scale btw). The closest earthquake to that, in the region, in the previous 100 years was 0.7M lower (and the 6th largest ever recorded, in the area). The Tohoku earthquake also resulted in one of the largest tsunamis ever recorded. We should note that a lot of rare things happened all at once, more than just the freak earthquake and freak tsunami. There is no such thing as perfect. But consider that there were no lives lost due to the reactor accident. Yes, there is economic damage, but that is the worst. Lives were not lost and the environment was not irreparably damaged. Nature has actually started to take back the region and it more looks like a scene out of I Am Legend rather than The Road or The Book of Eli. I do not intend to dismiss the event, as it is concerning (and we've learned a lot since then), but however you measure it coal or oil or gas have had far greater environmental (or human/health) impacts than nuclear. The difference is that it is more in our mind. Despite the Fukushima cleanup estimate (2x Chernobyl's) costing about 9x Deep Water Horizon (2010) I'll let you decide what costs more[0], even if we ignore all the costs to health and atmosphere. There simply is no free lunch. [0] https://ourworldindata.org/oil-spills https://ourworldindata.org/oil-spills
      - NorthOf33rd 6y ago
        There’s no free lunch but wind and solar are a hell of a lot cheaper than this.
        godelski 6y ago
        Economically cheaper, but that isn't the only factor that we're discussing. We're also talking health and environmental.
- p1mrx 6y ago
  > an evacuation of staff and it boils off during the resulting excursion. It is trivial to design a system that powers off when unstaffed. Without power, this reactor will SCRAM and passively switch to air cooling over the course of a month. Presumably, a skilled attacker could compromise the passive safety systems and force a meltdown, but wouldn't it be easier to steal some spent fuel and disperse it?
  - hansthehorse 6y ago
    Once an attacker is inside the plant, with just some Wiki knowledge, any plant is as good as melted down. It's a much better plan to simply drain the spent fuel pool.
    - p1mrx 6y ago
      I think it takes a bit more than Wiki knowledge to drain an in-ground pool... you would need to keep a large pump running for hours, under duress.
sandworm101 6y ago
You don't need to be an expert. Ask anyone who has owned an in-ground pool. Leaks are rare but do happen.
- godelski 6y ago
  Nuclear power plants were designed with this in mind. It would take a substantially larger earthquake to damage a nuclear power plant and cause it to leak than a commercial pool. Such a comparison is in bad faith and disingenuous.
  - AnimalMuppet 6y ago
    Cool it (pun intended) with the accusations of bad faith. Unless you have enough data to prove it, don't accuse it. "Substantially larger" is not the same as "impossible". And, given substantially larger consequences if a reactor pool breaks (compared to a swimming pool breaking), I don't think the question is out of line. We learned from Fukushima that natural disasters don't always follow the parameters that we expect them to.
  - ses1984 6y ago
    It's a people problem. People are fallible on the best days, assuming everyone did their very best from nuclear physicists to construction workers, mistakes are made. You take steps to reduce the risk. Research gets review. Engineering schematics get review. Construction gets inspection. Still some mistakes will get through. And people always act their very best all the time right? You can even have a perfect design, perfect construction, that is mismanaged years after it's built, after the original engineers and bureaucrats lose control. The same people problems apply to basically every human endeavor, but nuclear's capability to cause accidents that have a lasting impact is pretty scary. You don't feel even a twinge of existential dread when you think about? If you don't, then I don't think I want you working on a reactor.
    - markvdb 6y ago
      This. Humans are spectacularly bad at this kind of scale in time/project budget/size...
dylan604 6y ago
evaporation?

brandmeyer 6y ago

Many inland rectors are built on waterways. A plant can shut down due to drought. That's a slow enough process that you have plenty of advance warning, though.

jhallenworld 6y ago
Some are built on man-made reservoirs held together with dams..